diff options
Diffstat (limited to 'target/linux/generic/patches-3.8/100-overlayfs.patch')
| -rw-r--r-- | target/linux/generic/patches-3.8/100-overlayfs.patch | 3191 |
1 files changed, 0 insertions, 3191 deletions
diff --git a/target/linux/generic/patches-3.8/100-overlayfs.patch b/target/linux/generic/patches-3.8/100-overlayfs.patch deleted file mode 100644 index 26f373d1eb..0000000000 --- a/target/linux/generic/patches-3.8/100-overlayfs.patch +++ /dev/null @@ -1,3191 +0,0 @@ ---- a/Documentation/filesystems/Locking -+++ b/Documentation/filesystems/Locking -@@ -64,6 +64,7 @@ prototypes: - int (*atomic_open)(struct inode *, struct dentry *, - struct file *, unsigned open_flag, - umode_t create_mode, int *opened); -+ int (*dentry_open)(struct dentry *, struct file *, const struct cred *); - - locking rules: - all may block -@@ -91,6 +92,7 @@ removexattr: yes - fiemap: no - update_time: no - atomic_open: yes -+dentry_open: no - - Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_mutex on - victim. ---- /dev/null -+++ b/Documentation/filesystems/overlayfs.txt -@@ -0,0 +1,199 @@ -+Written by: Neil Brown <neilb@suse.de> -+ -+Overlay Filesystem -+================== -+ -+This document describes a prototype for a new approach to providing -+overlay-filesystem functionality in Linux (sometimes referred to as -+union-filesystems). An overlay-filesystem tries to present a -+filesystem which is the result over overlaying one filesystem on top -+of the other. -+ -+The result will inevitably fail to look exactly like a normal -+filesystem for various technical reasons. The expectation is that -+many use cases will be able to ignore these differences. -+ -+This approach is 'hybrid' because the objects that appear in the -+filesystem do not all appear to belong to that filesystem. In many -+cases an object accessed in the union will be indistinguishable -+from accessing the corresponding object from the original filesystem. -+This is most obvious from the 'st_dev' field returned by stat(2). -+ -+While directories will report an st_dev from the overlay-filesystem, -+all non-directory objects will report an st_dev from the lower or -+upper filesystem that is providing the object. Similarly st_ino will -+only be unique when combined with st_dev, and both of these can change -+over the lifetime of a non-directory object. Many applications and -+tools ignore these values and will not be affected. -+ -+Upper and Lower -+--------------- -+ -+An overlay filesystem combines two filesystems - an 'upper' filesystem -+and a 'lower' filesystem. When a name exists in both filesystems, the -+object in the 'upper' filesystem is visible while the object in the -+'lower' filesystem is either hidden or, in the case of directories, -+merged with the 'upper' object. -+ -+It would be more correct to refer to an upper and lower 'directory -+tree' rather than 'filesystem' as it is quite possible for both -+directory trees to be in the same filesystem and there is no -+requirement that the root of a filesystem be given for either upper or -+lower. -+ -+The lower filesystem can be any filesystem supported by Linux and does -+not need to be writable. The lower filesystem can even be another -+overlayfs. The upper filesystem will normally be writable and if it -+is it must support the creation of trusted.* extended attributes, and -+must provide valid d_type in readdir responses, at least for symbolic -+links - so NFS is not suitable. -+ -+A read-only overlay of two read-only filesystems may use any -+filesystem type. -+ -+Directories -+----------- -+ -+Overlaying mainly involves directories. If a given name appears in both -+upper and lower filesystems and refers to a non-directory in either, -+then the lower object is hidden - the name refers only to the upper -+object. -+ -+Where both upper and lower objects are directories, a merged directory -+is formed. -+ -+At mount time, the two directories given as mount options are combined -+into a merged directory: -+ -+ mount -t overlayfs overlayfs -olowerdir=/lower,upperdir=/upper /overlay -+ -+Then whenever a lookup is requested in such a merged directory, the -+lookup is performed in each actual directory and the combined result -+is cached in the dentry belonging to the overlay filesystem. If both -+actual lookups find directories, both are stored and a merged -+directory is created, otherwise only one is stored: the upper if it -+exists, else the lower. -+ -+Only the lists of names from directories are merged. Other content -+such as metadata and extended attributes are reported for the upper -+directory only. These attributes of the lower directory are hidden. -+ -+whiteouts and opaque directories -+-------------------------------- -+ -+In order to support rm and rmdir without changing the lower -+filesystem, an overlay filesystem needs to record in the upper filesystem -+that files have been removed. This is done using whiteouts and opaque -+directories (non-directories are always opaque). -+ -+The overlay filesystem uses extended attributes with a -+"trusted.overlay." prefix to record these details. -+ -+A whiteout is created as a symbolic link with target -+"(overlay-whiteout)" and with xattr "trusted.overlay.whiteout" set to "y". -+When a whiteout is found in the upper level of a merged directory, any -+matching name in the lower level is ignored, and the whiteout itself -+is also hidden. -+ -+A directory is made opaque by setting the xattr "trusted.overlay.opaque" -+to "y". Where the upper filesystem contains an opaque directory, any -+directory in the lower filesystem with the same name is ignored. -+ -+readdir -+------- -+ -+When a 'readdir' request is made on a merged directory, the upper and -+lower directories are each read and the name lists merged in the -+obvious way (upper is read first, then lower - entries that already -+exist are not re-added). This merged name list is cached in the -+'struct file' and so remains as long as the file is kept open. If the -+directory is opened and read by two processes at the same time, they -+will each have separate caches. A seekdir to the start of the -+directory (offset 0) followed by a readdir will cause the cache to be -+discarded and rebuilt. -+ -+This means that changes to the merged directory do not appear while a -+directory is being read. This is unlikely to be noticed by many -+programs. -+ -+seek offsets are assigned sequentially when the directories are read. -+Thus if -+ - read part of a directory -+ - remember an offset, and close the directory -+ - re-open the directory some time later -+ - seek to the remembered offset -+ -+there may be little correlation between the old and new locations in -+the list of filenames, particularly if anything has changed in the -+directory. -+ -+Readdir on directories that are not merged is simply handled by the -+underlying directory (upper or lower). -+ -+ -+Non-directories -+--------------- -+ -+Objects that are not directories (files, symlinks, device-special -+files etc.) are presented either from the upper or lower filesystem as -+appropriate. When a file in the lower filesystem is accessed in a way -+the requires write-access, such as opening for write access, changing -+some metadata etc., the file is first copied from the lower filesystem -+to the upper filesystem (copy_up). Note that creating a hard-link -+also requires copy_up, though of course creation of a symlink does -+not. -+ -+The copy_up may turn out to be unnecessary, for example if the file is -+opened for read-write but the data is not modified. -+ -+The copy_up process first makes sure that the containing directory -+exists in the upper filesystem - creating it and any parents as -+necessary. It then creates the object with the same metadata (owner, -+mode, mtime, symlink-target etc.) and then if the object is a file, the -+data is copied from the lower to the upper filesystem. Finally any -+extended attributes are copied up. -+ -+Once the copy_up is complete, the overlay filesystem simply -+provides direct access to the newly created file in the upper -+filesystem - future operations on the file are barely noticed by the -+overlay filesystem (though an operation on the name of the file such as -+rename or unlink will of course be noticed and handled). -+ -+ -+Non-standard behavior -+--------------------- -+ -+The copy_up operation essentially creates a new, identical file and -+moves it over to the old name. The new file may be on a different -+filesystem, so both st_dev and st_ino of the file may change. -+ -+Any open files referring to this inode will access the old data and -+metadata. Similarly any file locks obtained before copy_up will not -+apply to the copied up file. -+ -+On a file opened with O_RDONLY fchmod(2), fchown(2), futimesat(2) and -+fsetxattr(2) will fail with EROFS. -+ -+If a file with multiple hard links is copied up, then this will -+"break" the link. Changes will not be propagated to other names -+referring to the same inode. -+ -+Symlinks in /proc/PID/ and /proc/PID/fd which point to a non-directory -+object in overlayfs will not contain valid absolute paths, only -+relative paths leading up to the filesystem's root. This will be -+fixed in the future. -+ -+Some operations are not atomic, for example a crash during copy_up or -+rename will leave the filesystem in an inconsistent state. This will -+be addressed in the future. -+ -+Changes to underlying filesystems -+--------------------------------- -+ -+Offline changes, when the overlay is not mounted, are allowed to either -+the upper or the lower trees. -+ -+Changes to the underlying filesystems while part of a mounted overlay -+filesystem are not allowed. If the underlying filesystem is changed, -+the behavior of the overlay is undefined, though it will not result in -+a crash or deadlock. ---- a/Documentation/filesystems/vfs.txt -+++ b/Documentation/filesystems/vfs.txt -@@ -362,6 +362,7 @@ struct inode_operations { - int (*atomic_open)(struct inode *, struct dentry *, - struct file *, unsigned open_flag, - umode_t create_mode, int *opened); -+ int (*dentry_open)(struct dentry *, struct file *, const struct cred *); - }; - - Again, all methods are called without any locks being held, unless -@@ -681,6 +682,12 @@ struct address_space_operations { - but instead uses bmap to find out where the blocks in the file - are and uses those addresses directly. - -+ dentry_open: this is an alternative to f_op->open(), the difference is that -+ this method may open a file not necessarily originating from the same -+ filesystem as the one i_op->open() was called on. It may be -+ useful for stacking filesystems which want to allow native I/O directly -+ on underlying files. -+ - - invalidatepage: If a page has PagePrivate set, then invalidatepage - will be called when part or all of the page is to be removed ---- a/fs/ecryptfs/main.c -+++ b/fs/ecryptfs/main.c -@@ -567,6 +567,13 @@ static struct dentry *ecryptfs_mount(str - s->s_maxbytes = path.dentry->d_sb->s_maxbytes; - s->s_blocksize = path.dentry->d_sb->s_blocksize; - s->s_magic = ECRYPTFS_SUPER_MAGIC; -+ s->s_stack_depth = path.dentry->d_sb->s_stack_depth + 1; -+ -+ rc = -EINVAL; -+ if (s->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { -+ printk(KERN_ERR "eCryptfs: maximum fs stacking depth exceeded\n"); -+ goto out_free; -+ } - - inode = ecryptfs_get_inode(path.dentry->d_inode, s); - rc = PTR_ERR(inode); ---- a/fs/internal.h -+++ b/fs/internal.h -@@ -42,11 +42,6 @@ static inline int __sync_blockdev(struct - extern void __init chrdev_init(void); - - /* -- * namei.c -- */ --extern int __inode_permission(struct inode *, int); -- --/* - * namespace.c - */ - extern int copy_mount_options(const void __user *, unsigned long *); ---- a/fs/Kconfig -+++ b/fs/Kconfig -@@ -67,6 +67,7 @@ source "fs/quota/Kconfig" - - source "fs/autofs4/Kconfig" - source "fs/fuse/Kconfig" -+source "fs/overlayfs/Kconfig" - - config GENERIC_ACL - bool ---- a/fs/Makefile -+++ b/fs/Makefile -@@ -107,6 +107,7 @@ obj-$(CONFIG_QNX6FS_FS) += qnx6/ - obj-$(CONFIG_AUTOFS4_FS) += autofs4/ - obj-$(CONFIG_ADFS_FS) += adfs/ - obj-$(CONFIG_FUSE_FS) += fuse/ -+obj-$(CONFIG_OVERLAYFS_FS) += overlayfs/ - obj-$(CONFIG_UDF_FS) += udf/ - obj-$(CONFIG_SUN_OPENPROMFS) += openpromfs/ - obj-$(CONFIG_OMFS_FS) += omfs/ ---- a/fs/namei.c -+++ b/fs/namei.c -@@ -402,6 +402,7 @@ int __inode_permission(struct inode *ino - - return security_inode_permission(inode, mask); - } -+EXPORT_SYMBOL(__inode_permission); - - /** - * sb_permission - Check superblock-level permissions -@@ -2876,9 +2877,12 @@ finish_open_created: - error = may_open(&nd->path, acc_mode, open_flag); - if (error) - goto out; -- file->f_path.mnt = nd->path.mnt; -- error = finish_open(file, nd->path.dentry, NULL, opened); -- if (error) { -+ -+ BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ -+ error = vfs_open(&nd->path, file, current_cred()); -+ if (!error) { -+ *opened |= FILE_OPENED; -+ } else { - if (error == -EOPENSTALE) - goto stale_open; - goto out; ---- a/fs/namespace.c -+++ b/fs/namespace.c -@@ -1421,6 +1421,24 @@ void drop_collected_mounts(struct vfsmou - release_mounts(&umount_list); - } - -+struct vfsmount *clone_private_mount(struct path *path) -+{ -+ struct mount *old_mnt = real_mount(path->mnt); -+ struct mount *new_mnt; -+ -+ if (IS_MNT_UNBINDABLE(old_mnt)) -+ return ERR_PTR(-EINVAL); -+ -+ down_read(&namespace_sem); -+ new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE); -+ up_read(&namespace_sem); -+ if (!new_mnt) -+ return ERR_PTR(-ENOMEM); -+ -+ return &new_mnt->mnt; -+} -+EXPORT_SYMBOL_GPL(clone_private_mount); -+ - int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg, - struct vfsmount *root) - { ---- a/fs/open.c -+++ b/fs/open.c -@@ -816,8 +816,7 @@ struct file *dentry_open(const struct pa - return ERR_PTR(error); - - f->f_flags = flags; -- f->f_path = *path; -- error = do_dentry_open(f, NULL, cred); -+ error = vfs_open(path, f, cred); - if (!error) { - error = open_check_o_direct(f); - if (error) { -@@ -832,6 +831,26 @@ struct file *dentry_open(const struct pa - } - EXPORT_SYMBOL(dentry_open); - -+/** -+ * vfs_open - open the file at the given path -+ * @path: path to open -+ * @filp: newly allocated file with f_flag initialized -+ * @cred: credentials to use -+ */ -+int vfs_open(const struct path *path, struct file *filp, -+ const struct cred *cred) -+{ -+ struct inode *inode = path->dentry->d_inode; -+ -+ if (inode->i_op->dentry_open) -+ return inode->i_op->dentry_open(path->dentry, filp, cred); -+ else { -+ filp->f_path = *path; -+ return do_dentry_open(filp, NULL, cred); -+ } -+} -+EXPORT_SYMBOL(vfs_open); -+ - static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op) - { - int lookup_flags = 0; ---- /dev/null -+++ b/fs/overlayfs/copy_up.c -@@ -0,0 +1,385 @@ -+/* -+ * -+ * Copyright (C) 2011 Novell Inc. -+ * -+ * This program is free software; you can redistribute it and/or modify it -+ * under the terms of the GNU General Public License version 2 as published by -+ * the Free Software Foundation. -+ */ -+ -+#include <linux/fs.h> -+#include <linux/slab.h> -+#include <linux/file.h> -+#include <linux/splice.h> -+#include <linux/xattr.h> -+#include <linux/security.h> -+#include <linux/uaccess.h> -+#include <linux/sched.h> -+#include "overlayfs.h" -+ -+#define OVL_COPY_UP_CHUNK_SIZE (1 << 20) -+ -+static int ovl_copy_up_xattr(struct dentry *old, struct dentry *new) -+{ -+ ssize_t list_size, size; -+ char *buf, *name, *value; -+ int error; -+ -+ if (!old->d_inode->i_op->getxattr || -+ !new->d_inode->i_op->getxattr) -+ return 0; -+ -+ list_size = vfs_listxattr(old, NULL, 0); -+ if (list_size <= 0) { -+ if (list_size == -EOPNOTSUPP) -+ return 0; -+ return list_size; -+ } -+ -+ buf = kzalloc(list_size, GFP_KERNEL); -+ if (!buf) -+ return -ENOMEM; -+ -+ error = -ENOMEM; -+ value = kmalloc(XATTR_SIZE_MAX, GFP_KERNEL); -+ if (!value) -+ goto out; -+ -+ list_size = vfs_listxattr(old, buf, list_size); -+ if (list_size <= 0) { -+ error = list_size; -+ goto out_free_value; -+ } -+ -+ for (name = buf; name < (buf + list_size); name += strlen(name) + 1) { -+ size = vfs_getxattr(old, name, value, XATTR_SIZE_MAX); -+ if (size <= 0) { -+ error = size; -+ goto out_free_value; -+ } -+ error = vfs_setxattr(new, name, value, size, 0); -+ if (error) -+ goto out_free_value; -+ } -+ -+out_free_value: -+ kfree(value); -+out: -+ kfree(buf); -+ return error; -+} -+ -+static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len) -+{ -+ struct file *old_file; -+ struct file *new_file; -+ int error = 0; -+ -+ if (len == 0) -+ return 0; -+ -+ old_file = ovl_path_open(old, O_RDONLY); -+ if (IS_ERR(old_file)) -+ return PTR_ERR(old_file); -+ -+ new_file = ovl_path_open(new, O_WRONLY); -+ if (IS_ERR(new_file)) { -+ error = PTR_ERR(new_file); -+ goto out_fput; -+ } -+ -+ /* FIXME: copy up sparse files efficiently */ -+ while (len) { -+ loff_t offset = new_file->f_pos; -+ size_t this_len = OVL_COPY_UP_CHUNK_SIZE; -+ long bytes; -+ -+ if (len < this_len) -+ this_len = len; -+ -+ if (signal_pending_state(TASK_KILLABLE, current)) { -+ error = -EINTR; -+ break; -+ } -+ -+ bytes = do_splice_direct(old_file, &offset, new_file, this_len, -+ SPLICE_F_MOVE); -+ if (bytes <= 0) { -+ error = bytes; -+ break; -+ } -+ -+ len -= bytes; -+ } -+ -+ fput(new_file); -+out_fput: -+ fput(old_file); -+ return error; -+} -+ -+static char *ovl_read_symlink(struct dentry *realdentry) -+{ -+ int res; -+ char *buf; -+ struct inode *inode = realdentry->d_inode; -+ mm_segment_t old_fs; -+ -+ res = -EINVAL; -+ if (!inode->i_op->readlink) -+ goto err; -+ -+ res = -ENOMEM; -+ buf = (char *) __get_free_page(GFP_KERNEL); -+ if (!buf) -+ goto err; -+ -+ old_fs = get_fs(); -+ set_fs(get_ds()); -+ /* The cast to a user pointer is valid due to the set_fs() */ -+ res = inode->i_op->readlink(realdentry, -+ (char __user *)buf, PAGE_SIZE - 1); -+ set_fs(old_fs); -+ if (res < 0) { -+ free_page((unsigned long) buf); -+ goto err; -+ } -+ buf[res] = '\0'; -+ -+ return buf; -+ -+err: -+ return ERR_PTR(res); -+} -+ -+static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat) -+{ -+ struct iattr attr = { -+ .ia_valid = -+ ATTR_ATIME | ATTR_MTIME | ATTR_ATIME_SET | ATTR_MTIME_SET, -+ .ia_atime = stat->atime, -+ .ia_mtime = stat->mtime, -+ }; -+ -+ return notify_change(upperdentry, &attr); -+} -+ -+static int ovl_set_mode(struct dentry *upperdentry, umode_t mode) -+{ -+ struct iattr attr = { -+ .ia_valid = ATTR_MODE, -+ .ia_mode = mode, -+ }; -+ -+ return notify_change(upperdentry, &attr); -+} -+ -+static int ovl_copy_up_locked(struct dentry *upperdir, struct dentry *dentry, -+ struct path *lowerpath, struct kstat *stat, -+ const char *link) -+{ -+ int err; -+ struct path newpath; -+ umode_t mode = stat->mode; -+ -+ /* Can't properly set mode on creation because of the umask */ -+ stat->mode &= S_IFMT; -+ -+ ovl_path_upper(dentry, &newpath); -+ WARN_ON(newpath.dentry); -+ newpath.dentry = ovl_upper_create(upperdir, dentry, stat, link); -+ if (IS_ERR(newpath.dentry)) -+ return PTR_ERR(newpath.dentry); -+ -+ if (S_ISREG(stat->mode)) { -+ err = ovl_copy_up_data(lowerpath, &newpath, stat->size); -+ if (err) -+ goto err_remove; -+ } -+ -+ err = ovl_copy_up_xattr(lowerpath->dentry, newpath.dentry); -+ if (err) -+ goto err_remove; -+ -+ mutex_lock(&newpath.dentry->d_inode->i_mutex); -+ if (!S_ISLNK(stat->mode)) -+ err = ovl_set_mode(newpath.dentry, mode); -+ if (!err) -+ err = ovl_set_timestamps(newpath.dentry, stat); -+ mutex_unlock(&newpath.dentry->d_inode->i_mutex); -+ if (err) -+ goto err_remove; -+ -+ ovl_dentry_update(dentry, newpath.dentry); -+ -+ /* -+ * Easiest way to get rid of the lower dentry reference is to -+ * drop this dentry. This is neither needed nor possible for -+ * directories. -+ */ -+ if (!S_ISDIR(stat->mode)) -+ d_drop(dentry); -+ -+ return 0; -+ -+err_remove: -+ if (S_ISDIR(stat->mode)) -+ vfs_rmdir(upperdir->d_inode, newpath.dentry); -+ else -+ vfs_unlink(upperdir->d_inode, newpath.dentry); -+ -+ dput(newpath.dentry); -+ -+ return err; -+} -+ -+/* -+ * Copy up a single dentry -+ * -+ * Directory renames only allowed on "pure upper" (already created on -+ * upper filesystem, never copied up). Directories which are on lower or -+ * are merged may not be renamed. For these -EXDEV is returned and -+ * userspace has to deal with it. This means, when copying up a -+ * directory we can rely on it and ancestors being stable. -+ * -+ * Non-directory renames start with copy up of source if necessary. The -+ * actual rename will only proceed once the copy up was successful. Copy -+ * up uses upper parent i_mutex for exclusion. Since rename can change -+ * d_parent it is possible that the copy up will lock the old parent. At -+ * that point the file will have already been copied up anyway. -+ */ -+static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry, -+ struct path *lowerpath, struct kstat *stat) -+{ -+ int err; -+ struct kstat pstat; -+ struct path parentpath; -+ struct dentry *upperdir; -+ const struct cred *old_cred; -+ struct cred *override_cred; -+ char *link = NULL; -+ -+ ovl_path_upper(parent, &parentpath); -+ upperdir = parentpath.dentry; -+ -+ err = vfs_getattr(parentpath.mnt, parentpath.dentry, &pstat); -+ if (err) -+ return err; -+ -+ if (S_ISLNK(stat->mode)) { -+ link = ovl_read_symlink(lowerpath->dentry); -+ if (IS_ERR(link)) -+ return PTR_ERR(link); -+ } -+ -+ err = -ENOMEM; -+ override_cred = prepare_creds(); -+ if (!override_cred) -+ goto out_free_link; -+ -+ override_cred->fsuid = stat->uid; -+ override_cred->fsgid = stat->gid; -+ /* -+ * CAP_SYS_ADMIN for copying up extended attributes -+ * CAP_DAC_OVERRIDE for create -+ * CAP_FOWNER for chmod, timestamp update -+ * CAP_FSETID for chmod -+ * CAP_MKNOD for mknod -+ */ -+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); -+ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); -+ cap_raise(override_cred->cap_effective, CAP_FOWNER); -+ cap_raise(override_cred->cap_effective, CAP_FSETID); -+ cap_raise(override_cred->cap_effective, CAP_MKNOD); -+ old_cred = override_creds(override_cred); -+ -+ mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT); -+ if (ovl_path_type(dentry) != OVL_PATH_LOWER) { -+ err = 0; -+ } else { -+ err = ovl_copy_up_locked(upperdir, dentry, lowerpath, -+ stat, link); -+ if (!err) { -+ /* Restore timestamps on parent (best effort) */ -+ ovl_set_timestamps(upperdir, &pstat); -+ } -+ } -+ -+ mutex_unlock(&upperdir->d_inode->i_mutex); -+ -+ revert_creds(old_cred); -+ put_cred(override_cred); -+ -+out_free_link: -+ if (link) -+ free_page((unsigned long) link); -+ -+ return err; -+} -+ -+int ovl_copy_up(struct dentry *dentry) -+{ -+ int err; -+ -+ err = 0; -+ while (!err) { -+ struct dentry *next; -+ struct dentry *parent; -+ struct path lowerpath; -+ struct kstat stat; -+ enum ovl_path_type type = ovl_path_type(dentry); -+ -+ if (type != OVL_PATH_LOWER) -+ break; -+ -+ next = dget(dentry); -+ /* find the topmost dentry not yet copied up */ -+ for (;;) { -+ parent = dget_parent(next); -+ -+ type = ovl_path_type(parent); -+ if (type != OVL_PATH_LOWER) -+ break; -+ -+ dput(next); -+ next = parent; -+ } -+ -+ ovl_path_lower(next, &lowerpath); -+ err = vfs_getattr(lowerpath.mnt, lowerpath.dentry, &stat); -+ if (!err) -+ err = ovl_copy_up_one(parent, next, &lowerpath, &stat); -+ -+ dput(parent); -+ dput(next); -+ } -+ -+ return err; -+} -+ -+/* Optimize by not copying up the file first and truncating later */ -+int ovl_copy_up_truncate(struct dentry *dentry, loff_t size) -+{ -+ int err; -+ struct kstat stat; -+ struct path lowerpath; -+ struct dentry *parent = dget_parent(dentry); -+ -+ err = ovl_copy_up(parent); -+ if (err) -+ goto out_dput_parent; -+ -+ ovl_path_lower(dentry, &lowerpath); -+ err = vfs_getattr(lowerpath.mnt, lowerpath.dentry, &stat); -+ if (err) -+ goto out_dput_parent; -+ -+ if (size < stat.size) -+ stat.size = size; -+ -+ err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat); -+ -+out_dput_parent: -+ dput(parent); -+ return err; -+} ---- /dev/null -+++ b/fs/overlayfs/dir.c -@@ -0,0 +1,604 @@ -+/* -+ * -+ * Copyright (C) 2011 Novell Inc. -+ * -+ * This program is free software; you can redistribute it and/or modify it -+ * under the terms of the GNU General Public License version 2 as published by -+ * the Free Software Foundation. -+ */ -+ -+#include <linux/fs.h> -+#include <linux/namei.h> -+#include <linux/xattr.h> -+#include <linux/security.h> -+#include <linux/cred.h> -+#include "overlayfs.h" -+ -+static const char *ovl_whiteout_symlink = "(overlay-whiteout)"; -+ -+static int ovl_whiteout(struct dentry *upperdir, struct dentry *dentry) -+{ -+ int err; -+ struct dentry *newdentry; -+ const struct cred *old_cred; -+ struct cred *override_cred; -+ -+ /* FIXME: recheck lower dentry to see if whiteout is really needed */ -+ -+ err = -ENOMEM; -+ override_cred = prepare_creds(); -+ if (!override_cred) -+ goto out; -+ -+ /* -+ * CAP_SYS_ADMIN for setxattr -+ * CAP_DAC_OVERRIDE for symlink creation -+ * CAP_FOWNER for unlink in sticky directory -+ */ -+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); -+ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); -+ cap_raise(override_cred->cap_effective, CAP_FOWNER); -+ override_cred->fsuid = GLOBAL_ROOT_UID; -+ override_cred->fsgid = GLOBAL_ROOT_GID; -+ old_cred = override_creds(override_cred); -+ -+ newdentry = lookup_one_len(dentry->d_name.name, upperdir, -+ dentry->d_name.len); -+ err = PTR_ERR(newdentry); -+ if (IS_ERR(newdentry)) -+ goto out_put_cred; -+ -+ /* Just been removed within the same locked region */ -+ WARN_ON(newdentry->d_inode); -+ -+ err = vfs_symlink(upperdir->d_inode, newdentry, ovl_whiteout_symlink); -+ if (err) -+ goto out_dput; -+ -+ ovl_dentry_version_inc(dentry->d_parent); -+ -+ err = vfs_setxattr(newdentry, ovl_whiteout_xattr, "y", 1, 0); -+ if (err) -+ vfs_unlink(upperdir->d_inode, newdentry); -+ -+out_dput: -+ dput(newdentry); -+out_put_cred: -+ revert_creds(old_cred); -+ put_cred(override_cred); -+out: -+ if (err) { -+ /* -+ * There's no way to recover from failure to whiteout. -+ * What should we do? Log a big fat error and... ? -+ */ -+ printk(KERN_ERR "overlayfs: ERROR - failed to whiteout '%s'\n", -+ dentry->d_name.name); -+ } -+ -+ return err; -+} -+ -+static struct dentry *ovl_lookup_create(struct dentry *upperdir, -+ struct dentry *template) -+{ -+ int err; -+ struct dentry *newdentry; -+ struct qstr *name = &template->d_name; -+ -+ newdentry = lookup_one_len(name->name, upperdir, name->len); -+ if (IS_ERR(newdentry)) -+ return newdentry; -+ -+ if (newdentry->d_inode) { -+ const struct cred *old_cred; -+ struct cred *override_cred; -+ -+ /* No need to check whiteout if lower parent is non-existent */ -+ err = -EEXIST; -+ if (!ovl_dentry_lower(template->d_parent)) -+ goto out_dput; -+ -+ if (!S_ISLNK(newdentry->d_inode->i_mode)) -+ goto out_dput; -+ -+ err = -ENOMEM; -+ override_cred = prepare_creds(); -+ if (!override_cred) -+ goto out_dput; -+ -+ /* -+ * CAP_SYS_ADMIN for getxattr -+ * CAP_FOWNER for unlink in sticky directory -+ */ -+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); -+ cap_raise(override_cred->cap_effective, CAP_FOWNER); -+ old_cred = override_creds(override_cred); -+ -+ err = -EEXIST; -+ if (ovl_is_whiteout(newdentry)) -+ err = vfs_unlink(upperdir->d_inode, newdentry); -+ -+ revert_creds(old_cred); -+ put_cred(override_cred); -+ if (err) -+ goto out_dput; -+ -+ dput(newdentry); -+ newdentry = lookup_one_len(name->name, upperdir, name->len); -+ if (IS_ERR(newdentry)) { -+ ovl_whiteout(upperdir, template); -+ return newdentry; -+ } -+ -+ /* -+ * Whiteout just been successfully removed, parent -+ * i_mutex is still held, there's no way the lookup -+ * could return positive. -+ */ -+ WARN_ON(newdentry->d_inode); -+ } -+ -+ return newdentry; -+ -+out_dput: -+ dput(newdentry); -+ return ERR_PTR(err); -+} -+ -+struct dentry *ovl_upper_create(struct dentry *upperdir, struct dentry *dentry, -+ struct kstat *stat, const char *link) -+{ -+ int err; -+ struct dentry *newdentry; -+ struct inode *dir = upperdir->d_inode; -+ -+ newdentry = ovl_lookup_create(upperdir, dentry); -+ if (IS_ERR(newdentry)) -+ goto out; -+ -+ switch (stat->mode & S_IFMT) { -+ case S_IFREG: -+ err = vfs_create(dir, newdentry, stat->mode, NULL); -+ break; -+ -+ case S_IFDIR: -+ err = vfs_mkdir(dir, newdentry, stat->mode); -+ break; -+ -+ case S_IFCHR: -+ case S_IFBLK: -+ case S_IFIFO: -+ case S_IFSOCK: -+ err = vfs_mknod(dir, newdentry, stat->mode, stat->rdev); -+ break; -+ -+ case S_IFLNK: -+ err = vfs_symlink(dir, newdentry, link); -+ break; -+ -+ default: -+ err = -EPERM; -+ } -+ if (err) { -+ if (ovl_dentry_is_opaque(dentry)) -+ ovl_whiteout(upperdir, dentry); -+ dput(newdentry); -+ newdentry = ERR_PTR(err); -+ } else if (WARN_ON(!newdentry->d_inode)) { -+ /* -+ * Not quite sure if non-instantiated dentry is legal or not. -+ * VFS doesn't seem to care so check and warn here. -+ */ -+ dput(newdentry); -+ newdentry = ERR_PTR(-ENOENT); -+ } -+ -+out: -+ return newdentry; -+ -+} -+ -+static int ovl_set_opaque(struct dentry *upperdentry) -+{ -+ int err; -+ const struct cred *old_cred; -+ struct cred *override_cred; -+ -+ override_cred = prepare_creds(); -+ if (!override_cred) -+ return -ENOMEM; -+ -+ /* CAP_SYS_ADMIN for setxattr of "trusted" namespace */ -+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); -+ old_cred = override_creds(override_cred); -+ err = vfs_setxattr(upperdentry, ovl_opaque_xattr, "y", 1, 0); -+ revert_creds(old_cred); -+ put_cred(override_cred); -+ -+ return err; -+} -+ -+static int ovl_remove_opaque(struct dentry *upperdentry) -+{ -+ int err; -+ const struct cred *old_cred; -+ struct cred *override_cred; -+ -+ override_cred = prepare_creds(); -+ if (!override_cred) -+ return -ENOMEM; -+ -+ /* CAP_SYS_ADMIN for removexattr of "trusted" namespace */ -+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); -+ old_cred = override_creds(override_cred); -+ err = vfs_removexattr(upperdentry, ovl_opaque_xattr); -+ revert_creds(old_cred); -+ put_cred(override_cred); -+ -+ return err; -+} -+ -+static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry, -+ struct kstat *stat) -+{ -+ int err; -+ enum ovl_path_type type; -+ struct path realpath; -+ -+ type = ovl_path_real(dentry, &realpath); -+ err = vfs_getattr(realpath.mnt, realpath.dentry, stat); -+ if (err) -+ return err; -+ -+ stat->dev = dentry->d_sb->s_dev; -+ stat->ino = dentry->d_inode->i_ino; -+ -+ /* -+ * It's probably not worth it to count subdirs to get the -+ * correct link count. nlink=1 seems to pacify 'find' and -+ * other utilities. -+ */ -+ if (type == OVL_PATH_MERGE) -+ stat->nlink = 1; -+ -+ return 0; -+} -+ -+static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev, -+ const char *link) -+{ -+ int err; -+ struct dentry *newdentry; -+ struct dentry *upperdir; -+ struct inode *inode; -+ struct kstat stat = { -+ .mode = mode, -+ .rdev = rdev, -+ }; -+ -+ err = -ENOMEM; -+ inode = ovl_new_inode(dentry->d_sb, mode, dentry->d_fsdata); -+ if (!inode) -+ goto out; -+ -+ err = ovl_copy_up(dentry->d_parent); -+ if (err) -+ goto out_iput; -+ -+ upperdir = ovl_dentry_upper(dentry->d_parent); -+ mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT); -+ -+ newdentry = ovl_upper_create(upperdir, dentry, &stat, link); -+ err = PTR_ERR(newdentry); -+ if (IS_ERR(newdentry)) -+ goto out_unlock; -+ -+ ovl_dentry_version_inc(dentry->d_parent); -+ if (ovl_dentry_is_opaque(dentry) && S_ISDIR(mode)) { -+ err = ovl_set_opaque(newdentry); -+ if (err) { -+ vfs_rmdir(upperdir->d_inode, newdentry); -+ ovl_whiteout(upperdir, dentry); -+ goto out_dput; -+ } -+ } -+ ovl_dentry_update(dentry, newdentry); -+ ovl_copyattr(newdentry->d_inode, inode); -+ d_instantiate(dentry, inode); -+ inode = NULL; -+ newdentry = NULL; -+ err = 0; -+ -+out_dput: -+ dput(newdentry); -+out_unlock: -+ mutex_unlock(&upperdir->d_inode->i_mutex); -+out_iput: -+ iput(inode); -+out: -+ return err; -+} -+ -+static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode, -+ bool excl) -+{ -+ return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL); -+} -+ -+static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) -+{ -+ return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL); -+} -+ -+static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, -+ dev_t rdev) -+{ -+ return ovl_create_object(dentry, mode, rdev, NULL); -+} -+ -+static int ovl_symlink(struct inode *dir, struct dentry *dentry, -+ const char *link) -+{ -+ return ovl_create_object(dentry, S_IFLNK, 0, link); -+} -+ -+static int ovl_do_remove(struct dentry *dentry, bool is_dir) -+{ -+ int err; -+ enum ovl_path_type type; -+ struct path realpath; -+ struct dentry *upperdir; -+ -+ err = ovl_copy_up(dentry->d_parent); -+ if (err) -+ return err; -+ -+ upperdir = ovl_dentry_upper(dentry->d_parent); -+ mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT); -+ type = ovl_path_real(dentry, &realpath); -+ if (type != OVL_PATH_LOWER) { -+ err = -ESTALE; -+ if (realpath.dentry->d_parent != upperdir) -+ goto out_d_drop; -+ -+ /* FIXME: create whiteout up front and rename to target */ -+ -+ if (is_dir) -+ err = vfs_rmdir(upperdir->d_inode, realpath.dentry); -+ else -+ err = vfs_unlink(upperdir->d_inode, realpath.dentry); -+ if (err) -+ goto out_d_drop; -+ -+ ovl_dentry_version_inc(dentry->d_parent); -+ } -+ -+ if (type != OVL_PATH_UPPER || ovl_dentry_is_opaque(dentry)) -+ err = ovl_whiteout(upperdir, dentry); -+ -+ /* -+ * Keeping this dentry hashed would mean having to release -+ * upperpath/lowerpath, which could only be done if we are the -+ * sole user of this dentry. Too tricky... Just unhash for -+ * now. -+ */ -+out_d_drop: -+ d_drop(dentry); -+ mutex_unlock(&upperdir->d_inode->i_mutex); -+ -+ return err; -+} -+ -+static int ovl_unlink(struct inode *dir, struct dentry *dentry) -+{ -+ return ovl_do_remove(dentry, false); -+} -+ -+ -+static int ovl_rmdir(struct inode *dir, struct dentry *dentry) -+{ -+ int err; -+ enum ovl_path_type type; -+ -+ type = ovl_path_type(dentry); -+ if (type != OVL_PATH_UPPER) { -+ err = ovl_check_empty_and_clear(dentry, type); -+ if (err) -+ return err; -+ } -+ -+ return ovl_do_remove(dentry, true); -+} -+ -+static int ovl_link(struct dentry *old, struct inode *newdir, -+ struct dentry *new) -+{ -+ int err; -+ struct dentry *olddentry; -+ struct dentry *newdentry; -+ struct dentry *upperdir; -+ struct inode *newinode; -+ -+ err = ovl_copy_up(old); -+ if (err) -+ goto out; -+ -+ err = ovl_copy_up(new->d_parent); -+ if (err) -+ goto out; -+ -+ upperdir = ovl_dentry_upper(new->d_parent); -+ mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT); -+ newdentry = ovl_lookup_create(upperdir, new); -+ err = PTR_ERR(newdentry); -+ if (IS_ERR(newdentry)) -+ goto out_unlock; -+ -+ olddentry = ovl_dentry_upper(old); -+ err = vfs_link(olddentry, upperdir->d_inode, newdentry); -+ if (!err) { -+ if (WARN_ON(!newdentry->d_inode)) { -+ dput(newdentry); -+ err = -ENOENT; -+ goto out_unlock; -+ } -+ newinode = ovl_new_inode(old->d_sb, newdentry->d_inode->i_mode, -+ new->d_fsdata); -+ if (!newinode) -+ goto link_fail; -+ ovl_copyattr(upperdir->d_inode, newinode); -+ -+ ovl_dentry_version_inc(new->d_parent); -+ ovl_dentry_update(new, newdentry); -+ -+ d_instantiate(new, newinode); -+ } else { -+link_fail: -+ if (ovl_dentry_is_opaque(new)) -+ ovl_whiteout(upperdir, new); -+ dput(newdentry); -+ } -+out_unlock: -+ mutex_unlock(&upperdir->d_inode->i_mutex); -+out: -+ return err; -+ -+} -+ -+static int ovl_rename(struct inode *olddir, struct dentry *old, -+ struct inode *newdir, struct dentry *new) -+{ -+ int err; -+ enum ovl_path_type old_type; -+ enum ovl_path_type new_type; -+ struct dentry *old_upperdir; -+ struct dentry *new_upperdir; -+ struct dentry *olddentry; -+ struct dentry *newdentry; -+ struct dentry *trap; -+ bool old_opaque; -+ bool new_opaque; -+ bool new_create = false; -+ bool is_dir = S_ISDIR(old->d_inode->i_mode); -+ -+ /* Don't copy up directory trees */ -+ old_type = ovl_path_type(old); -+ if (old_type != OVL_PATH_UPPER && is_dir) -+ return -EXDEV; -+ -+ if (new->d_inode) { -+ new_type = ovl_path_type(new); -+ -+ if (new_type == OVL_PATH_LOWER && old_type == OVL_PATH_LOWER) { -+ if (ovl_dentry_lower(old)->d_inode == -+ ovl_dentry_lower(new)->d_inode) -+ return 0; -+ } -+ if (new_type != OVL_PATH_LOWER && old_type != OVL_PATH_LOWER) { -+ if (ovl_dentry_upper(old)->d_inode == -+ ovl_dentry_upper(new)->d_inode) -+ return 0; -+ } -+ -+ if (new_type != OVL_PATH_UPPER && -+ S_ISDIR(new->d_inode->i_mode)) { -+ err = ovl_check_empty_and_clear(new, new_type); -+ if (err) -+ return err; -+ } -+ } else { -+ new_type = OVL_PATH_UPPER; -+ } -+ -+ err = ovl_copy_up(old); -+ if (err) -+ return err; -+ -+ err = ovl_copy_up(new->d_parent); -+ if (err) -+ return err; -+ -+ old_upperdir = ovl_dentry_upper(old->d_parent); -+ new_upperdir = ovl_dentry_upper(new->d_parent); -+ -+ trap = lock_rename(new_upperdir, old_upperdir); -+ -+ olddentry = ovl_dentry_upper(old); -+ newdentry = ovl_dentry_upper(new); -+ if (newdentry) { -+ dget(newdentry); -+ } else { -+ new_create = true; -+ newdentry = ovl_lookup_create(new_upperdir, new); -+ err = PTR_ERR(newdentry); -+ if (IS_ERR(newdentry)) -+ goto out_unlock; -+ } -+ -+ err = -ESTALE; -+ if (olddentry->d_parent != old_upperdir) -+ goto out_dput; -+ if (newdentry->d_parent != new_upperdir) -+ goto out_dput; -+ if (olddentry == trap) -+ goto out_dput; -+ if (newdentry == trap) -+ goto out_dput; -+ -+ old_opaque = ovl_dentry_is_opaque(old); -+ new_opaque = ovl_dentry_is_opaque(new) || new_type != OVL_PATH_UPPER; -+ -+ if (is_dir && !old_opaque && new_opaque) { -+ err = ovl_set_opaque(olddentry); -+ if (err) -+ goto out_dput; -+ } -+ -+ err = vfs_rename(old_upperdir->d_inode, olddentry, -+ new_upperdir->d_inode, newdentry); -+ -+ if (err) { -+ if (new_create && ovl_dentry_is_opaque(new)) -+ ovl_whiteout(new_upperdir, new); -+ if (is_dir && !old_opaque && new_opaque) -+ ovl_remove_opaque(olddentry); -+ goto out_dput; -+ } -+ -+ if (old_type != OVL_PATH_UPPER || old_opaque) -+ err = ovl_whiteout(old_upperdir, old); -+ if (is_dir && old_opaque && !new_opaque) -+ ovl_remove_opaque(olddentry); -+ -+ if (old_opaque != new_opaque) -+ ovl_dentry_set_opaque(old, new_opaque); -+ -+ ovl_dentry_version_inc(old->d_parent); -+ ovl_dentry_version_inc(new->d_parent); -+ -+out_dput: -+ dput(newdentry); -+out_unlock: -+ unlock_rename(new_upperdir, old_upperdir); -+ return err; -+} -+ -+const struct inode_operations ovl_dir_inode_operations = { -+ .lookup = ovl_lookup, -+ .mkdir = ovl_mkdir, -+ .symlink = ovl_symlink, -+ .unlink = ovl_unlink, -+ .rmdir = ovl_rmdir, -+ .rename = ovl_rename, -+ .link = ovl_link, -+ .setattr = ovl_setattr, -+ .create = ovl_create, -+ .mknod = ovl_mknod, -+ .permission = ovl_permission, -+ .getattr = ovl_dir_getattr, -+ .setxattr = ovl_setxattr, -+ .getxattr = ovl_getxattr, -+ .listxattr = ovl_listxattr, -+ .removexattr = ovl_removexattr, -+}; ---- /dev/null -+++ b/fs/overlayfs/inode.c -@@ -0,0 +1,372 @@ -+/* -+ * -+ * Copyright (C) 2011 Novell Inc. -+ * -+ * This program is free software; you can redistribute it and/or modify it -+ * under the terms of the GNU General Public License version 2 as published by -+ * the Free Software Foundation. -+ */ -+ -+#include <linux/fs.h> -+#include <linux/slab.h> -+#include <linux/xattr.h> -+#include "overlayfs.h" -+ -+int ovl_setattr(struct dentry *dentry, struct iattr *attr) -+{ -+ struct dentry *upperdentry; -+ int err; -+ -+ if ((attr->ia_valid & ATTR_SIZE) && !ovl_dentry_upper(dentry)) -+ err = ovl_copy_up_truncate(dentry, attr->ia_size); -+ else -+ err = ovl_copy_up(dentry); -+ if (err) -+ return err; -+ -+ upperdentry = ovl_dentry_upper(dentry); -+ -+ if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) -+ attr->ia_valid &= ~ATTR_MODE; -+ -+ mutex_lock(&upperdentry->d_inode->i_mutex); -+ err = notify_change(upperdentry, attr); -+ if (!err) -+ ovl_copyattr(upperdentry->d_inode, dentry->d_inode); -+ mutex_unlock(&upperdentry->d_inode->i_mutex); -+ -+ return err; -+} -+ -+static int ovl_getattr(struct vfsmount *mnt, struct dentry *dentry, -+ struct kstat *stat) -+{ -+ struct path realpath; -+ -+ ovl_path_real(dentry, &realpath); -+ return vfs_getattr(realpath.mnt, realpath.dentry, stat); -+} -+ -+int ovl_permission(struct inode *inode, int mask) -+{ -+ struct ovl_entry *oe; -+ struct dentry *alias = NULL; -+ struct inode *realinode; -+ struct dentry *realdentry; -+ bool is_upper; -+ int err; -+ -+ if (S_ISDIR(inode->i_mode)) { -+ oe = inode->i_private; -+ } else if (mask & MAY_NOT_BLOCK) { -+ return -ECHILD; -+ } else { -+ /* -+ * For non-directories find an alias and get the info -+ * from there. -+ */ -+ alias = d_find_any_alias(inode); -+ if (WARN_ON(!alias)) -+ return -ENOENT; -+ -+ oe = alias->d_fsdata; -+ } -+ -+ realdentry = ovl_entry_real(oe, &is_upper); -+ -+ /* Careful in RCU walk mode */ -+ realinode = ACCESS_ONCE(realdentry->d_inode); -+ if (!realinode) { -+ WARN_ON(!(mask & MAY_NOT_BLOCK)); -+ err = -ENOENT; -+ goto out_dput; -+ } -+ -+ if (mask & MAY_WRITE) { -+ umode_t mode = realinode->i_mode; -+ -+ /* -+ * Writes will always be redirected to upper layer, so -+ * ignore lower layer being read-only. -+ * -+ * If the overlay itself is read-only then proceed -+ * with the permission check, don't return EROFS. -+ * This will only happen if this is the lower layer of -+ * another overlayfs. -+ * -+ * If upper fs becomes read-only after the overlay was -+ * constructed return EROFS to prevent modification of -+ * upper layer. -+ */ -+ err = -EROFS; -+ if (is_upper && !IS_RDONLY(inode) && IS_RDONLY(realinode) && -+ (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) -+ goto out_dput; -+ } -+ -+ err = __inode_permission(realinode, mask); -+out_dput: -+ dput(alias); -+ return err; -+} -+ -+ -+struct ovl_link_data { -+ struct dentry *realdentry; -+ void *cookie; -+}; -+ -+static void *ovl_follow_link(struct dentry *dentry, struct nameidata *nd) -+{ -+ void *ret; -+ struct dentry *realdentry; -+ struct inode *realinode; -+ -+ realdentry = ovl_dentry_real(dentry); -+ realinode = realdentry->d_inode; -+ -+ if (WARN_ON(!realinode->i_op->follow_link)) -+ return ERR_PTR(-EPERM); -+ -+ ret = realinode->i_op->follow_link(realdentry, nd); -+ if (IS_ERR(ret)) -+ return ret; -+ -+ if (realinode->i_op->put_link) { -+ struct ovl_link_data *data; -+ -+ data = kmalloc(sizeof(struct ovl_link_data), GFP_KERNEL); -+ if (!data) { -+ realinode->i_op->put_link(realdentry, nd, ret); -+ return ERR_PTR(-ENOMEM); -+ } -+ data->realdentry = realdentry; -+ data->cookie = ret; -+ -+ return data; -+ } else { -+ return NULL; -+ } -+} -+ -+static void ovl_put_link(struct dentry *dentry, struct nameidata *nd, void *c) -+{ -+ struct inode *realinode; -+ struct ovl_link_data *data = c; -+ -+ if (!data) -+ return; -+ -+ realinode = data->realdentry->d_inode; -+ realinode->i_op->put_link(data->realdentry, nd, data->cookie); -+ kfree(data); -+} -+ -+static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz) -+{ -+ struct path realpath; -+ struct inode *realinode; -+ -+ ovl_path_real(dentry, &realpath); -+ realinode = realpath.dentry->d_inode; -+ -+ if (!realinode->i_op->readlink) -+ return -EINVAL; -+ -+ touch_atime(&realpath); -+ -+ return realinode->i_op->readlink(realpath.dentry, buf, bufsiz); -+} -+ -+ -+static bool ovl_is_private_xattr(const char *name) -+{ -+ return strncmp(name, "trusted.overlay.", 14) == 0; -+} -+ -+int ovl_setxattr(struct dentry *dentry, const char *name, -+ const void *value, size_t size, int flags) -+{ -+ int err; -+ struct dentry *upperdentry; -+ -+ if (ovl_is_private_xattr(name)) -+ return -EPERM; -+ -+ err = ovl_copy_up(dentry); -+ if (err) -+ return err; -+ -+ upperdentry = ovl_dentry_upper(dentry); -+ return vfs_setxattr(upperdentry, name, value, size, flags); -+} -+ -+ssize_t ovl_getxattr(struct dentry *dentry, const char *name, -+ void *value, size_t size) -+{ -+ if (ovl_path_type(dentry->d_parent) == OVL_PATH_MERGE && -+ ovl_is_private_xattr(name)) -+ return -ENODATA; -+ -+ return vfs_getxattr(ovl_dentry_real(dentry), name, value, size); -+} -+ -+ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) -+{ -+ ssize_t res; -+ int off; -+ -+ res = vfs_listxattr(ovl_dentry_real(dentry), list, size); -+ if (res <= 0 || size == 0) -+ return res; -+ -+ if (ovl_path_type(dentry->d_parent) != OVL_PATH_MERGE) -+ return res; -+ -+ /* filter out private xattrs */ -+ for (off = 0; off < res;) { -+ char *s = list + off; -+ size_t slen = strlen(s) + 1; -+ -+ BUG_ON(off + slen > res); -+ -+ if (ovl_is_private_xattr(s)) { -+ res -= slen; -+ memmove(s, s + slen, res - off); -+ } else { -+ off += slen; -+ } -+ } -+ -+ return res; -+} -+ -+int ovl_removexattr(struct dentry *dentry, const char *name) -+{ -+ int err; -+ struct path realpath; -+ enum ovl_path_type type; -+ -+ if (ovl_path_type(dentry->d_parent) == OVL_PATH_MERGE && -+ ovl_is_private_xattr(name)) -+ return -ENODATA; -+ -+ type = ovl_path_real(dentry, &realpath); -+ if (type == OVL_PATH_LOWER) { -+ err = vfs_getxattr(realpath.dentry, name, NULL, 0); -+ if (err < 0) -+ return err; -+ -+ err = ovl_copy_up(dentry); -+ if (err) -+ return err; -+ -+ ovl_path_upper(dentry, &realpath); -+ } -+ -+ return vfs_removexattr(realpath.dentry, name); -+} -+ -+static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type, -+ struct dentry *realdentry) -+{ -+ if (type != OVL_PATH_LOWER) -+ return false; -+ -+ if (special_file(realdentry->d_inode->i_mode)) -+ return false; -+ -+ if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC)) -+ return false; -+ -+ return true; -+} -+ -+static int ovl_dentry_open(struct dentry *dentry, struct file *file, -+ const struct cred *cred) -+{ -+ int err; -+ struct path realpath; -+ enum ovl_path_type type; -+ -+ type = ovl_path_real(dentry, &realpath); -+ if (ovl_open_need_copy_up(file->f_flags, type, realpath.dentry)) { -+ if (file->f_flags & O_TRUNC) -+ err = ovl_copy_up_truncate(dentry, 0); -+ else -+ err = ovl_copy_up(dentry); -+ if (err) -+ return err; -+ -+ ovl_path_upper(dentry, &realpath); -+ } -+ -+ return vfs_open(&realpath, file, cred); -+} -+ -+static const struct inode_operations ovl_file_inode_operations = { -+ .setattr = ovl_setattr, -+ .permission = ovl_permission, -+ .getattr = ovl_getattr, -+ .setxattr = ovl_setxattr, -+ .getxattr = ovl_getxattr, -+ .listxattr = ovl_listxattr, -+ .removexattr = ovl_removexattr, -+ .dentry_open = ovl_dentry_open, -+}; -+ -+static const struct inode_operations ovl_symlink_inode_operations = { -+ .setattr = ovl_setattr, -+ .follow_link = ovl_follow_link, -+ .put_link = ovl_put_link, -+ .readlink = ovl_readlink, -+ .getattr = ovl_getattr, -+ .setxattr = ovl_setxattr, -+ .getxattr = ovl_getxattr, -+ .listxattr = ovl_listxattr, -+ .removexattr = ovl_removexattr, -+}; -+ -+struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, -+ struct ovl_entry *oe) -+{ -+ struct inode *inode; -+ -+ inode = new_inode(sb); -+ if (!inode) -+ return NULL; -+ -+ mode &= S_IFMT; -+ -+ inode->i_ino = get_next_ino(); -+ inode->i_mode = mode; -+ inode->i_flags |= S_NOATIME | S_NOCMTIME; -+ -+ switch (mode) { -+ case S_IFDIR: -+ inode->i_private = oe; -+ inode->i_op = &ovl_dir_inode_operations; -+ inode->i_fop = &ovl_dir_operations; -+ break; -+ -+ case S_IFLNK: -+ inode->i_op = &ovl_symlink_inode_operations; -+ break; -+ -+ case S_IFREG: -+ case S_IFSOCK: -+ case S_IFBLK: -+ case S_IFCHR: -+ case S_IFIFO: -+ inode->i_op = &ovl_file_inode_operations; -+ break; -+ -+ default: -+ WARN(1, "illegal file type: %i\n", mode); -+ iput(inode); -+ inode = NULL; -+ } -+ -+ return inode; -+ -+} ---- /dev/null -+++ b/fs/overlayfs/Kconfig -@@ -0,0 +1,4 @@ -+config OVERLAYFS_FS -+ tristate "Overlay filesystem support" -+ help -+ Add support for overlay filesystem. ---- /dev/null -+++ b/fs/overlayfs/Makefile -@@ -0,0 +1,7 @@ -+# -+# Makefile for the overlay filesystem. -+# -+ -+obj-$(CONFIG_OVERLAYFS_FS) += overlayfs.o -+ -+overlayfs-objs := super.o inode.o dir.o readdir.o copy_up.o ---- /dev/null -+++ b/fs/overlayfs/overlayfs.h -@@ -0,0 +1,70 @@ -+/* -+ * -+ * Copyright (C) 2011 Novell Inc. -+ * -+ * This program is free software; you can redistribute it and/or modify it -+ * under the terms of the GNU General Public License version 2 as published by -+ * the Free Software Foundation. -+ */ -+ -+struct ovl_entry; -+ -+enum ovl_path_type { -+ OVL_PATH_UPPER, -+ OVL_PATH_MERGE, -+ OVL_PATH_LOWER, -+}; -+ -+extern const char *ovl_opaque_xattr; -+extern const char *ovl_whiteout_xattr; -+extern const struct dentry_operations ovl_dentry_operations; -+ -+enum ovl_path_type ovl_path_type(struct dentry *dentry); -+u64 ovl_dentry_version_get(struct dentry *dentry); -+void ovl_dentry_version_inc(struct dentry *dentry); -+void ovl_path_upper(struct dentry *dentry, struct path *path); -+void ovl_path_lower(struct dentry *dentry, struct path *path); -+enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path); -+struct dentry *ovl_dentry_upper(struct dentry *dentry); -+struct dentry *ovl_dentry_lower(struct dentry *dentry); -+struct dentry *ovl_dentry_real(struct dentry *dentry); -+struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper); -+bool ovl_dentry_is_opaque(struct dentry *dentry); -+void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque); -+bool ovl_is_whiteout(struct dentry *dentry); -+void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry); -+struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, -+ unsigned int flags); -+struct file *ovl_path_open(struct path *path, int flags); -+ -+struct dentry *ovl_upper_create(struct dentry *upperdir, struct dentry *dentry, -+ struct kstat *stat, const char *link); -+ -+/* readdir.c */ -+extern const struct file_operations ovl_dir_operations; -+int ovl_check_empty_and_clear(struct dentry *dentry, enum ovl_path_type type); -+ -+/* inode.c */ -+int ovl_setattr(struct dentry *dentry, struct iattr *attr); -+int ovl_permission(struct inode *inode, int mask); -+int ovl_setxattr(struct dentry *dentry, const char *name, -+ const void *value, size_t size, int flags); -+ssize_t ovl_getxattr(struct dentry *dentry, const char *name, -+ void *value, size_t size); -+ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size); -+int ovl_removexattr(struct dentry *dentry, const char *name); -+ -+struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, -+ struct ovl_entry *oe); -+static inline void ovl_copyattr(struct inode *from, struct inode *to) -+{ -+ to->i_uid = from->i_uid; -+ to->i_gid = from->i_gid; -+} -+ -+/* dir.c */ -+extern const struct inode_operations ovl_dir_inode_operations; -+ -+/* copy_up.c */ -+int ovl_copy_up(struct dentry *dentry); -+int ovl_copy_up_truncate(struct dentry *dentry, loff_t size); ---- /dev/null -+++ b/fs/overlayfs/readdir.c -@@ -0,0 +1,566 @@ -+/* -+ * -+ * Copyright (C) 2011 Novell Inc. -+ * -+ * This program is free software; you can redistribute it and/or modify it -+ * under the terms of the GNU General Public License version 2 as published by -+ * the Free Software Foundation. -+ */ -+ -+#include <linux/fs.h> -+#include <linux/slab.h> -+#include <linux/namei.h> -+#include <linux/file.h> -+#include <linux/xattr.h> -+#include <linux/rbtree.h> -+#include <linux/security.h> -+#include <linux/cred.h> -+#include "overlayfs.h" -+ -+struct ovl_cache_entry { -+ const char *name; -+ unsigned int len; -+ unsigned int type; -+ u64 ino; -+ bool is_whiteout; -+ struct list_head l_node; -+ struct rb_node node; -+}; -+ -+struct ovl_readdir_data { -+ struct rb_root *root; -+ struct list_head *list; -+ struct list_head *middle; -+ struct dentry *dir; -+ int count; -+ int err; -+}; -+ -+struct ovl_dir_file { -+ bool is_real; -+ bool is_cached; -+ struct list_head cursor; -+ u64 cache_version; -+ struct list_head cache; -+ struct file *realfile; -+}; -+ -+static struct ovl_cache_entry *ovl_cache_entry_from_node(struct rb_node *n) -+{ -+ return container_of(n, struct ovl_cache_entry, node); -+} -+ -+static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root, -+ const char *name, int len) -+{ -+ struct rb_node *node = root->rb_node; -+ int cmp; -+ -+ while (node) { -+ struct ovl_cache_entry *p = ovl_cache_entry_from_node(node); -+ -+ cmp = strncmp(name, p->name, len); -+ if (cmp > 0) -+ node = p->node.rb_right; -+ else if (cmp < 0 || len < p->len) -+ node = p->node.rb_left; -+ else -+ return p; -+ } -+ -+ return NULL; -+} -+ -+static struct ovl_cache_entry *ovl_cache_entry_new(const char *name, int len, -+ u64 ino, unsigned int d_type) -+{ -+ struct ovl_cache_entry *p; -+ -+ p = kmalloc(sizeof(*p) + len + 1, GFP_KERNEL); -+ if (p) { -+ char *name_copy = (char *) (p + 1); -+ memcpy(name_copy, name, len); -+ name_copy[len] = '\0'; -+ p->name = name_copy; -+ p->len = len; -+ p->type = d_type; -+ p->ino = ino; -+ p->is_whiteout = false; -+ } -+ -+ return p; -+} -+ -+static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd, -+ const char *name, int len, u64 ino, -+ unsigned int d_type) -+{ -+ struct rb_node **newp = &rdd->root->rb_node; -+ struct rb_node *parent = NULL; -+ struct ovl_cache_entry *p; -+ -+ while (*newp) { -+ int cmp; -+ struct ovl_cache_entry *tmp; -+ -+ parent = *newp; -+ tmp = ovl_cache_entry_from_node(*newp); -+ cmp = strncmp(name, tmp->name, len); -+ if (cmp > 0) -+ newp = &tmp->node.rb_right; -+ else if (cmp < 0 || len < tmp->len) -+ newp = &tmp->node.rb_left; -+ else -+ return 0; -+ } -+ -+ p = ovl_cache_entry_new(name, len, ino, d_type); -+ if (p == NULL) -+ return -ENOMEM; -+ -+ list_add_tail(&p->l_node, rdd->list); -+ rb_link_node(&p->node, parent, newp); -+ rb_insert_color(&p->node, rdd->root); -+ -+ return 0; -+} -+ -+static int ovl_fill_lower(void *buf, const char *name, int namelen, -+ loff_t offset, u64 ino, unsigned int d_type) -+{ -+ struct ovl_readdir_data *rdd = buf; -+ struct ovl_cache_entry *p; -+ -+ rdd->count++; -+ p = ovl_cache_entry_find(rdd->root, name, namelen); -+ if (p) { -+ list_move_tail(&p->l_node, rdd->middle); -+ } else { -+ p = ovl_cache_entry_new(name, namelen, ino, d_type); -+ if (p == NULL) -+ rdd->err = -ENOMEM; -+ else -+ list_add_tail(&p->l_node, rdd->middle); -+ } -+ -+ return rdd->err; -+} -+ -+static void ovl_cache_free(struct list_head *list) -+{ -+ struct ovl_cache_entry *p; -+ struct ovl_cache_entry *n; -+ -+ list_for_each_entry_safe(p, n, list, l_node) -+ kfree(p); -+ -+ INIT_LIST_HEAD(list); -+} -+ -+static int ovl_fill_upper(void *buf, const char *name, int namelen, -+ loff_t offset, u64 ino, unsigned int d_type) -+{ -+ struct ovl_readdir_data *rdd = buf; -+ -+ rdd->count++; -+ return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type); -+} -+ -+static inline int ovl_dir_read(struct path *realpath, -+ struct ovl_readdir_data *rdd, filldir_t filler) -+{ -+ struct file *realfile; -+ int err; -+ -+ realfile = ovl_path_open(realpath, O_RDONLY | O_DIRECTORY); -+ if (IS_ERR(realfile)) -+ return PTR_ERR(realfile); -+ -+ do { -+ rdd->count = 0; -+ rdd->err = 0; -+ err = vfs_readdir(realfile, filler, rdd); -+ if (err >= 0) -+ err = rdd->err; -+ } while (!err && rdd->count); -+ fput(realfile); -+ -+ return 0; -+} -+ -+static void ovl_dir_reset(struct file *file) -+{ -+ struct ovl_dir_file *od = file->private_data; -+ enum ovl_path_type type = ovl_path_type(file->f_path.dentry); -+ -+ if (ovl_dentry_version_get(file->f_path.dentry) != od->cache_version) { -+ list_del_init(&od->cursor); -+ ovl_cache_free(&od->cache); -+ od->is_cached = false; -+ } -+ WARN_ON(!od->is_real && type != OVL_PATH_MERGE); -+ if (od->is_real && type == OVL_PATH_MERGE) { -+ fput(od->realfile); -+ od->realfile = NULL; -+ od->is_real = false; -+ } -+} -+ -+static int ovl_dir_mark_whiteouts(struct ovl_readdir_data *rdd) -+{ -+ struct ovl_cache_entry *p; -+ struct dentry *dentry; -+ const struct cred *old_cred; -+ struct cred *override_cred; -+ -+ override_cred = prepare_creds(); -+ if (!override_cred) { -+ ovl_cache_free(rdd->list); -+ return -ENOMEM; -+ } -+ -+ /* -+ * CAP_SYS_ADMIN for getxattr -+ * CAP_DAC_OVERRIDE for lookup -+ */ -+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); -+ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); -+ old_cred = override_creds(override_cred); -+ -+ mutex_lock(&rdd->dir->d_inode->i_mutex); -+ list_for_each_entry(p, rdd->list, l_node) { -+ if (p->type != DT_LNK) -+ continue; -+ -+ dentry = lookup_one_len(p->name, rdd->dir, p->len); -+ if (IS_ERR(dentry)) -+ continue; -+ -+ p->is_whiteout = ovl_is_whiteout(dentry); -+ dput(dentry); -+ } -+ mutex_unlock(&rdd->dir->d_inode->i_mutex); -+ -+ revert_creds(old_cred); -+ put_cred(override_cred); -+ -+ return 0; -+} -+ -+static inline int ovl_dir_read_merged(struct path *upperpath, -+ struct path *lowerpath, -+ struct ovl_readdir_data *rdd) -+{ -+ int err; -+ struct rb_root root = RB_ROOT; -+ struct list_head middle; -+ -+ rdd->root = &root; -+ if (upperpath->dentry) { -+ rdd->dir = upperpath->dentry; -+ err = ovl_dir_read(upperpath, rdd, ovl_fill_upper); -+ if (err) -+ goto out; -+ -+ err = ovl_dir_mark_whiteouts(rdd); -+ if (err) -+ goto out; -+ } -+ /* -+ * Insert lowerpath entries before upperpath ones, this allows -+ * offsets to be reasonably constant -+ */ -+ list_add(&middle, rdd->list); -+ rdd->middle = &middle; -+ err = ovl_dir_read(lowerpath, rdd, ovl_fill_lower); -+ list_del(&middle); -+out: -+ rdd->root = NULL; -+ -+ return err; -+} -+ -+static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos) -+{ -+ struct list_head *l; -+ loff_t off; -+ -+ l = od->cache.next; -+ for (off = 0; off < pos; off++) { -+ if (l == &od->cache) -+ break; -+ l = l->next; -+ } -+ list_move_tail(&od->cursor, l); -+} -+ -+static int ovl_readdir(struct file *file, void *buf, filldir_t filler) -+{ -+ struct ovl_dir_file *od = file->private_data; -+ int res; -+ -+ if (!file->f_pos) -+ ovl_dir_reset(file); -+ -+ if (od->is_real) { -+ res = vfs_readdir(od->realfile, filler, buf); -+ file->f_pos = od->realfile->f_pos; -+ -+ return res; -+ } -+ -+ if (!od->is_cached) { -+ struct path lowerpath; -+ struct path upperpath; -+ struct ovl_readdir_data rdd = { .list = &od->cache }; -+ -+ ovl_path_lower(file->f_path.dentry, &lowerpath); -+ ovl_path_upper(file->f_path.dentry, &upperpath); -+ -+ res = ovl_dir_read_merged(&upperpath, &lowerpath, &rdd); -+ if (res) { -+ ovl_cache_free(rdd.list); -+ return res; -+ } -+ -+ od->cache_version = ovl_dentry_version_get(file->f_path.dentry); -+ od->is_cached = true; -+ -+ ovl_seek_cursor(od, file->f_pos); -+ } -+ -+ while (od->cursor.next != &od->cache) { -+ int over; -+ loff_t off; -+ struct ovl_cache_entry *p; -+ -+ p = list_entry(od->cursor.next, struct ovl_cache_entry, l_node); -+ off = file->f_pos; -+ if (!p->is_whiteout) { -+ over = filler(buf, p->name, p->len, off, p->ino, -+ p->type); -+ if (over) -+ break; -+ } -+ file->f_pos++; -+ list_move(&od->cursor, &p->l_node); -+ } -+ -+ return 0; -+} -+ -+static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin) -+{ -+ loff_t res; -+ struct ovl_dir_file *od = file->private_data; -+ -+ mutex_lock(&file->f_dentry->d_inode->i_mutex); -+ if (!file->f_pos) -+ ovl_dir_reset(file); -+ -+ if (od->is_real) { -+ res = vfs_llseek(od->realfile, offset, origin); -+ file->f_pos = od->realfile->f_pos; -+ } else { -+ res = -EINVAL; -+ -+ switch (origin) { -+ case SEEK_CUR: -+ offset += file->f_pos; -+ break; -+ case SEEK_SET: -+ break; -+ default: -+ goto out_unlock; -+ } -+ if (offset < 0) -+ goto out_unlock; -+ -+ if (offset != file->f_pos) { -+ file->f_pos = offset; -+ if (od->is_cached) -+ ovl_seek_cursor(od, offset); -+ } -+ res = offset; -+ } -+out_unlock: -+ mutex_unlock(&file->f_dentry->d_inode->i_mutex); -+ -+ return res; -+} -+ -+static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end, -+ int datasync) -+{ -+ struct ovl_dir_file *od = file->private_data; -+ -+ /* May need to reopen directory if it got copied up */ -+ if (!od->realfile) { -+ struct path upperpath; -+ -+ ovl_path_upper(file->f_path.dentry, &upperpath); -+ od->realfile = ovl_path_open(&upperpath, O_RDONLY); -+ if (IS_ERR(od->realfile)) -+ return PTR_ERR(od->realfile); -+ } -+ -+ return vfs_fsync_range(od->realfile, start, end, datasync); -+} -+ -+static int ovl_dir_release(struct inode *inode, struct file *file) -+{ -+ struct ovl_dir_file *od = file->private_data; -+ -+ list_del(&od->cursor); -+ ovl_cache_free(&od->cache); -+ if (od->realfile) -+ fput(od->realfile); -+ kfree(od); -+ -+ return 0; -+} -+ -+static int ovl_dir_open(struct inode *inode, struct file *file) -+{ -+ struct path realpath; -+ struct file *realfile; -+ struct ovl_dir_file *od; -+ enum ovl_path_type type; -+ -+ od = kzalloc(sizeof(struct ovl_dir_file), GFP_KERNEL); -+ if (!od) -+ return -ENOMEM; -+ -+ type = ovl_path_real(file->f_path.dentry, &realpath); -+ realfile = ovl_path_open(&realpath, file->f_flags); -+ if (IS_ERR(realfile)) { -+ kfree(od); -+ return PTR_ERR(realfile); -+ } -+ INIT_LIST_HEAD(&od->cache); -+ INIT_LIST_HEAD(&od->cursor); -+ od->is_cached = false; -+ od->realfile = realfile; -+ od->is_real = (type != OVL_PATH_MERGE); -+ file->private_data = od; -+ -+ return 0; -+} -+ -+const struct file_operations ovl_dir_operations = { -+ .read = generic_read_dir, -+ .open = ovl_dir_open, -+ .readdir = ovl_readdir, -+ .llseek = ovl_dir_llseek, -+ .fsync = ovl_dir_fsync, -+ .release = ovl_dir_release, -+}; -+ -+static int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list) -+{ -+ int err; -+ struct path lowerpath; -+ struct path upperpath; -+ struct ovl_cache_entry *p; -+ struct ovl_readdir_data rdd = { .list = list }; -+ -+ ovl_path_upper(dentry, &upperpath); -+ ovl_path_lower(dentry, &lowerpath); -+ -+ err = ovl_dir_read_merged(&upperpath, &lowerpath, &rdd); -+ if (err) -+ return err; -+ -+ err = 0; -+ -+ list_for_each_entry(p, list, l_node) { -+ if (p->is_whiteout) -+ continue; -+ -+ if (p->name[0] == '.') { -+ if (p->len == 1) -+ continue; -+ if (p->len == 2 && p->name[1] == '.') -+ continue; -+ } -+ err = -ENOTEMPTY; -+ break; -+ } -+ -+ return err; -+} -+ -+static int ovl_remove_whiteouts(struct dentry *dir, struct list_head *list) -+{ -+ struct path upperpath; -+ struct dentry *upperdir; -+ struct ovl_cache_entry *p; -+ const struct cred *old_cred; -+ struct cred *override_cred; -+ int err; -+ -+ ovl_path_upper(dir, &upperpath); -+ upperdir = upperpath.dentry; -+ -+ override_cred = prepare_creds(); -+ if (!override_cred) -+ return -ENOMEM; -+ -+ /* -+ * CAP_DAC_OVERRIDE for lookup and unlink -+ * CAP_SYS_ADMIN for setxattr of "trusted" namespace -+ * CAP_FOWNER for unlink in sticky directory -+ */ -+ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); -+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); -+ cap_raise(override_cred->cap_effective, CAP_FOWNER); -+ old_cred = override_creds(override_cred); -+ -+ err = vfs_setxattr(upperdir, ovl_opaque_xattr, "y", 1, 0); -+ if (err) -+ goto out_revert_creds; -+ -+ mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT); -+ list_for_each_entry(p, list, l_node) { -+ struct dentry *dentry; -+ int ret; -+ -+ if (!p->is_whiteout) -+ continue; -+ -+ dentry = lookup_one_len(p->name, upperdir, p->len); -+ if (IS_ERR(dentry)) { -+ printk(KERN_WARNING -+ "overlayfs: failed to lookup whiteout %.*s: %li\n", -+ p->len, p->name, PTR_ERR(dentry)); -+ continue; -+ } -+ ret = vfs_unlink(upperdir->d_inode, dentry); -+ dput(dentry); -+ if (ret) -+ printk(KERN_WARNING -+ "overlayfs: failed to unlink whiteout %.*s: %i\n", -+ p->len, p->name, ret); -+ } -+ mutex_unlock(&upperdir->d_inode->i_mutex); -+ -+out_revert_creds: -+ revert_creds(old_cred); -+ put_cred(override_cred); -+ -+ return err; -+} -+ -+int ovl_check_empty_and_clear(struct dentry *dentry, enum ovl_path_type type) -+{ -+ int err; -+ LIST_HEAD(list); -+ -+ err = ovl_check_empty_dir(dentry, &list); -+ if (!err && type == OVL_PATH_MERGE) -+ err = ovl_remove_whiteouts(dentry, &list); -+ -+ ovl_cache_free(&list); -+ -+ return err; -+} ---- /dev/null -+++ b/fs/overlayfs/super.c -@@ -0,0 +1,685 @@ -+/* -+ * -+ * Copyright (C) 2011 Novell Inc. -+ * -+ * This program is free software; you can redistribute it and/or modify it -+ * under the terms of the GNU General Public License version 2 as published by -+ * the Free Software Foundation. -+ */ -+ -+#include <linux/fs.h> -+#include <linux/namei.h> -+#include <linux/xattr.h> -+#include <linux/security.h> -+#include <linux/mount.h> -+#include <linux/slab.h> -+#include <linux/parser.h> -+#include <linux/module.h> -+#include <linux/cred.h> -+#include <linux/sched.h> -+#include <linux/statfs.h> -+#include <linux/seq_file.h> -+#include "overlayfs.h" -+ -+MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>"); -+MODULE_DESCRIPTION("Overlay filesystem"); -+MODULE_LICENSE("GPL"); -+ -+#define OVERLAYFS_SUPER_MAGIC 0x794c764f -+ -+struct ovl_config { -+ char *lowerdir; -+ char *upperdir; -+}; -+ -+/* private information held for overlayfs's superblock */ -+struct ovl_fs { -+ struct vfsmount *upper_mnt; -+ struct vfsmount *lower_mnt; -+ long lower_namelen; -+ /* pathnames of lower and upper dirs, for show_options */ -+ struct ovl_config config; -+}; -+ -+/* private information held for every overlayfs dentry */ -+struct ovl_entry { -+ /* -+ * Keep "double reference" on upper dentries, so that -+ * d_delete() doesn't think it's OK to reset d_inode to NULL. -+ */ -+ struct dentry *__upperdentry; -+ struct dentry *lowerdentry; -+ union { -+ struct { -+ u64 version; -+ bool opaque; -+ }; -+ struct rcu_head rcu; -+ }; -+}; -+ -+const char *ovl_whiteout_xattr = "trusted.overlay.whiteout"; -+const char *ovl_opaque_xattr = "trusted.overlay.opaque"; -+ -+ -+enum ovl_path_type ovl_path_type(struct dentry *dentry) -+{ -+ struct ovl_entry *oe = dentry->d_fsdata; -+ -+ if (oe->__upperdentry) { -+ if (oe->lowerdentry && S_ISDIR(dentry->d_inode->i_mode)) -+ return OVL_PATH_MERGE; -+ else -+ return OVL_PATH_UPPER; -+ } else { -+ return OVL_PATH_LOWER; -+ } -+} -+ -+static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe) -+{ -+ struct dentry *upperdentry = ACCESS_ONCE(oe->__upperdentry); -+ smp_read_barrier_depends(); -+ return upperdentry; -+} -+ -+void ovl_path_upper(struct dentry *dentry, struct path *path) -+{ -+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info; -+ struct ovl_entry *oe = dentry->d_fsdata; -+ -+ path->mnt = ofs->upper_mnt; -+ path->dentry = ovl_upperdentry_dereference(oe); -+} -+ -+void ovl_path_lower(struct dentry *dentry, struct path *path) -+{ -+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info; -+ struct ovl_entry *oe = dentry->d_fsdata; -+ -+ path->mnt = ofs->lower_mnt; -+ path->dentry = oe->lowerdentry; -+} -+ -+enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path) -+{ -+ -+ enum ovl_path_type type = ovl_path_type(dentry); -+ -+ if (type == OVL_PATH_LOWER) -+ ovl_path_lower(dentry, path); -+ else -+ ovl_path_upper(dentry, path); -+ -+ return type; -+} -+ -+struct dentry *ovl_dentry_upper(struct dentry *dentry) -+{ -+ struct ovl_entry *oe = dentry->d_fsdata; -+ -+ return ovl_upperdentry_dereference(oe); -+} -+ -+struct dentry *ovl_dentry_lower(struct dentry *dentry) -+{ -+ struct ovl_entry *oe = dentry->d_fsdata; -+ -+ return oe->lowerdentry; -+} -+ -+struct dentry *ovl_dentry_real(struct dentry *dentry) -+{ -+ struct ovl_entry *oe = dentry->d_fsdata; -+ struct dentry *realdentry; -+ -+ realdentry = ovl_upperdentry_dereference(oe); -+ if (!realdentry) -+ realdentry = oe->lowerdentry; -+ -+ return realdentry; -+} -+ -+struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper) -+{ -+ struct dentry *realdentry; -+ -+ realdentry = ovl_upperdentry_dereference(oe); -+ if (realdentry) { -+ *is_upper = true; -+ } else { -+ realdentry = oe->lowerdentry; -+ *is_upper = false; -+ } -+ return realdentry; -+} -+ -+bool ovl_dentry_is_opaque(struct dentry *dentry) -+{ -+ struct ovl_entry *oe = dentry->d_fsdata; -+ return oe->opaque; -+} -+ -+void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque) -+{ -+ struct ovl_entry *oe = dentry->d_fsdata; -+ oe->opaque = opaque; -+} -+ -+void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry) -+{ -+ struct ovl_entry *oe = dentry->d_fsdata; -+ -+ WARN_ON(!mutex_is_locked(&upperdentry->d_parent->d_inode->i_mutex)); -+ WARN_ON(oe->__upperdentry); -+ BUG_ON(!upperdentry->d_inode); -+ smp_wmb(); -+ oe->__upperdentry = dget(upperdentry); -+} -+ -+void ovl_dentry_version_inc(struct dentry *dentry) -+{ -+ struct ovl_entry *oe = dentry->d_fsdata; -+ -+ WARN_ON(!mutex_is_locked(&dentry->d_inode->i_mutex)); -+ oe->version++; -+} -+ -+u64 ovl_dentry_version_get(struct dentry *dentry) -+{ -+ struct ovl_entry *oe = dentry->d_fsdata; -+ -+ WARN_ON(!mutex_is_locked(&dentry->d_inode->i_mutex)); -+ return oe->version; -+} -+ -+bool ovl_is_whiteout(struct dentry *dentry) -+{ -+ int res; -+ char val; -+ -+ if (!dentry) -+ return false; -+ if (!dentry->d_inode) -+ return false; -+ if (!S_ISLNK(dentry->d_inode->i_mode)) -+ return false; -+ -+ res = vfs_getxattr(dentry, ovl_whiteout_xattr, &val, 1); -+ if (res == 1 && val == 'y') -+ return true; -+ -+ return false; -+} -+ -+static bool ovl_is_opaquedir(struct dentry *dentry) -+{ -+ int res; -+ char val; -+ -+ if (!S_ISDIR(dentry->d_inode->i_mode)) -+ return false; -+ -+ res = vfs_getxattr(dentry, ovl_opaque_xattr, &val, 1); -+ if (res == 1 && val == 'y') -+ return true; -+ -+ return false; -+} -+ -+static void ovl_entry_free(struct rcu_head *head) -+{ -+ struct ovl_entry *oe = container_of(head, struct ovl_entry, rcu); -+ kfree(oe); -+} -+ -+static void ovl_dentry_release(struct dentry *dentry) -+{ -+ struct ovl_entry *oe = dentry->d_fsdata; -+ -+ if (oe) { -+ dput(oe->__upperdentry); -+ dput(oe->__upperdentry); -+ dput(oe->lowerdentry); -+ call_rcu(&oe->rcu, ovl_entry_free); -+ } -+} -+ -+const struct dentry_operations ovl_dentry_operations = { -+ .d_release = ovl_dentry_release, -+}; -+ -+static struct ovl_entry *ovl_alloc_entry(void) -+{ -+ return kzalloc(sizeof(struct ovl_entry), GFP_KERNEL); -+} -+ -+static inline struct dentry *ovl_lookup_real(struct dentry *dir, -+ struct qstr *name) -+{ -+ struct dentry *dentry; -+ -+ mutex_lock(&dir->d_inode->i_mutex); -+ dentry = lookup_one_len(name->name, dir, name->len); -+ mutex_unlock(&dir->d_inode->i_mutex); -+ -+ if (IS_ERR(dentry)) { -+ if (PTR_ERR(dentry) == -ENOENT) -+ dentry = NULL; -+ } else if (!dentry->d_inode) { -+ dput(dentry); -+ dentry = NULL; -+ } -+ return dentry; -+} -+ -+static int ovl_do_lookup(struct dentry *dentry) -+{ -+ struct ovl_entry *oe; -+ struct dentry *upperdir; -+ struct dentry *lowerdir; -+ struct dentry *upperdentry = NULL; -+ struct dentry *lowerdentry = NULL; -+ struct inode *inode = NULL; -+ int err; -+ -+ err = -ENOMEM; -+ oe = ovl_alloc_entry(); -+ if (!oe) -+ goto out; -+ -+ upperdir = ovl_dentry_upper(dentry->d_parent); -+ lowerdir = ovl_dentry_lower(dentry->d_parent); -+ -+ if (upperdir) { -+ upperdentry = ovl_lookup_real(upperdir, &dentry->d_name); -+ err = PTR_ERR(upperdentry); -+ if (IS_ERR(upperdentry)) -+ goto out_put_dir; -+ -+ if (lowerdir && upperdentry && -+ (S_ISLNK(upperdentry->d_inode->i_mode) || -+ S_ISDIR(upperdentry->d_inode->i_mode))) { -+ const struct cred *old_cred; -+ struct cred *override_cred; -+ -+ err = -ENOMEM; -+ override_cred = prepare_creds(); -+ if (!override_cred) -+ goto out_dput_upper; -+ -+ /* CAP_SYS_ADMIN needed for getxattr */ -+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); -+ old_cred = override_creds(override_cred); -+ -+ if (ovl_is_opaquedir(upperdentry)) { -+ oe->opaque = true; -+ } else if (ovl_is_whiteout(upperdentry)) { -+ dput(upperdentry); -+ upperdentry = NULL; -+ oe->opaque = true; -+ } -+ revert_creds(old_cred); -+ put_cred(override_cred); -+ } -+ } -+ if (lowerdir && !oe->opaque) { -+ lowerdentry = ovl_lookup_real(lowerdir, &dentry->d_name); -+ err = PTR_ERR(lowerdentry); -+ if (IS_ERR(lowerdentry)) -+ goto out_dput_upper; -+ } -+ -+ if (lowerdentry && upperdentry && -+ (!S_ISDIR(upperdentry->d_inode->i_mode) || -+ !S_ISDIR(lowerdentry->d_inode->i_mode))) { -+ dput(lowerdentry); -+ lowerdentry = NULL; -+ oe->opaque = true; -+ } -+ -+ if (lowerdentry || upperdentry) { -+ struct dentry *realdentry; -+ -+ realdentry = upperdentry ? upperdentry : lowerdentry; -+ err = -ENOMEM; -+ inode = ovl_new_inode(dentry->d_sb, realdentry->d_inode->i_mode, -+ oe); -+ if (!inode) -+ goto out_dput; -+ ovl_copyattr(realdentry->d_inode, inode); -+ } -+ -+ if (upperdentry) -+ oe->__upperdentry = dget(upperdentry); -+ -+ if (lowerdentry) -+ oe->lowerdentry = lowerdentry; -+ -+ dentry->d_fsdata = oe; -+ dentry->d_op = &ovl_dentry_operations; -+ d_add(dentry, inode); -+ -+ return 0; -+ -+out_dput: -+ dput(lowerdentry); -+out_dput_upper: -+ dput(upperdentry); -+out_put_dir: -+ kfree(oe); -+out: -+ return err; -+} -+ -+struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, -+ unsigned int flags) -+{ -+ int err = ovl_do_lookup(dentry); -+ -+ if (err) -+ return ERR_PTR(err); -+ -+ return NULL; -+} -+ -+struct file *ovl_path_open(struct path *path, int flags) -+{ -+ path_get(path); -+ return dentry_open(path, flags, current_cred()); -+} -+ -+static void ovl_put_super(struct super_block *sb) -+{ -+ struct ovl_fs *ufs = sb->s_fs_info; -+ -+ if (!(sb->s_flags & MS_RDONLY)) -+ mnt_drop_write(ufs->upper_mnt); -+ -+ mntput(ufs->upper_mnt); -+ mntput(ufs->lower_mnt); -+ -+ kfree(ufs->config.lowerdir); -+ kfree(ufs->config.upperdir); -+ kfree(ufs); -+} -+ -+static int ovl_remount_fs(struct super_block *sb, int *flagsp, char *data) -+{ -+ int flags = *flagsp; -+ struct ovl_fs *ufs = sb->s_fs_info; -+ -+ /* When remounting rw or ro, we need to adjust the write access to the -+ * upper fs. -+ */ -+ if (((flags ^ sb->s_flags) & MS_RDONLY) == 0) -+ /* No change to readonly status */ -+ return 0; -+ -+ if (flags & MS_RDONLY) { -+ mnt_drop_write(ufs->upper_mnt); -+ return 0; -+ } else -+ return mnt_want_write(ufs->upper_mnt); -+} -+ -+/** -+ * ovl_statfs -+ * @sb: The overlayfs super block -+ * @buf: The struct kstatfs to fill in with stats -+ * -+ * Get the filesystem statistics. As writes always target the upper layer -+ * filesystem pass the statfs to the same filesystem. -+ */ -+static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf) -+{ -+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info; -+ struct dentry *root_dentry = dentry->d_sb->s_root; -+ struct path path; -+ int err; -+ -+ ovl_path_upper(root_dentry, &path); -+ -+ err = vfs_statfs(&path, buf); -+ if (!err) { -+ buf->f_namelen = max(buf->f_namelen, ofs->lower_namelen); -+ buf->f_type = OVERLAYFS_SUPER_MAGIC; -+ } -+ -+ return err; -+} -+ -+/** -+ * ovl_show_options -+ * -+ * Prints the mount options for a given superblock. -+ * Returns zero; does not fail. -+ */ -+static int ovl_show_options(struct seq_file *m, struct dentry *dentry) -+{ -+ struct super_block *sb = dentry->d_sb; -+ struct ovl_fs *ufs = sb->s_fs_info; -+ -+ seq_printf(m, ",lowerdir=%s", ufs->config.lowerdir); -+ seq_printf(m, ",upperdir=%s", ufs->config.upperdir); -+ return 0; -+} -+ -+static const struct super_operations ovl_super_operations = { -+ .put_super = ovl_put_super, -+ .remount_fs = ovl_remount_fs, -+ .statfs = ovl_statfs, -+ .show_options = ovl_show_options, -+}; -+ -+enum { -+ Opt_lowerdir, -+ Opt_upperdir, -+ Opt_err, -+}; -+ -+static const match_table_t ovl_tokens = { -+ {Opt_lowerdir, "lowerdir=%s"}, -+ {Opt_upperdir, "upperdir=%s"}, -+ {Opt_err, NULL} -+}; -+ -+static int ovl_parse_opt(char *opt, struct ovl_config *config) -+{ -+ char *p; -+ -+ config->upperdir = NULL; -+ config->lowerdir = NULL; -+ -+ while ((p = strsep(&opt, ",")) != NULL) { -+ int token; -+ substring_t args[MAX_OPT_ARGS]; -+ -+ if (!*p) -+ continue; -+ -+ token = match_token(p, ovl_tokens, args); -+ switch (token) { -+ case Opt_upperdir: -+ kfree(config->upperdir); -+ config->upperdir = match_strdup(&args[0]); -+ if (!config->upperdir) -+ return -ENOMEM; -+ break; -+ -+ case Opt_lowerdir: -+ kfree(config->lowerdir); -+ config->lowerdir = match_strdup(&args[0]); -+ if (!config->lowerdir) -+ return -ENOMEM; -+ break; -+ -+ default: -+ return -EINVAL; -+ } -+ } -+ return 0; -+} -+ -+static int ovl_fill_super(struct super_block *sb, void *data, int silent) -+{ -+ struct path lowerpath; -+ struct path upperpath; -+ struct inode *root_inode; -+ struct dentry *root_dentry; -+ struct ovl_entry *oe; -+ struct ovl_fs *ufs; -+ struct kstatfs statfs; -+ int err; -+ -+ err = -ENOMEM; -+ ufs = kmalloc(sizeof(struct ovl_fs), GFP_KERNEL); -+ if (!ufs) -+ goto out; -+ -+ err = ovl_parse_opt((char *) data, &ufs->config); -+ if (err) -+ goto out_free_ufs; -+ -+ err = -EINVAL; -+ if (!ufs->config.upperdir || !ufs->config.lowerdir) { -+ printk(KERN_ERR "overlayfs: missing upperdir or lowerdir\n"); -+ goto out_free_config; -+ } -+ -+ oe = ovl_alloc_entry(); -+ if (oe == NULL) -+ goto out_free_config; -+ -+ err = kern_path(ufs->config.upperdir, LOOKUP_FOLLOW, &upperpath); -+ if (err) -+ goto out_free_oe; -+ -+ err = kern_path(ufs->config.lowerdir, LOOKUP_FOLLOW, &lowerpath); -+ if (err) -+ goto out_put_upperpath; -+ -+ err = -ENOTDIR; -+ if (!S_ISDIR(upperpath.dentry->d_inode->i_mode) || -+ !S_ISDIR(lowerpath.dentry->d_inode->i_mode)) -+ goto out_put_lowerpath; -+ -+ err = vfs_statfs(&lowerpath, &statfs); -+ if (err) { -+ printk(KERN_ERR "overlayfs: statfs failed on lowerpath\n"); -+ goto out_put_lowerpath; -+ } -+ ufs->lower_namelen = statfs.f_namelen; -+ -+ sb->s_stack_depth = max(upperpath.mnt->mnt_sb->s_stack_depth, -+ lowerpath.mnt->mnt_sb->s_stack_depth) + 1; -+ -+ err = -EINVAL; -+ if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { -+ printk(KERN_ERR "overlayfs: maximum fs stacking depth exceeded\n"); -+ goto out_put_lowerpath; -+ } -+ -+ -+ ufs->upper_mnt = clone_private_mount(&upperpath); -+ err = PTR_ERR(ufs->upper_mnt); -+ if (IS_ERR(ufs->upper_mnt)) { -+ printk(KERN_ERR "overlayfs: failed to clone upperpath\n"); -+ goto out_put_lowerpath; -+ } -+ -+ ufs->lower_mnt = clone_private_mount(&lowerpath); -+ err = PTR_ERR(ufs->lower_mnt); -+ if (IS_ERR(ufs->lower_mnt)) { -+ printk(KERN_ERR "overlayfs: failed to clone lowerpath\n"); -+ goto out_put_upper_mnt; -+ } -+ -+ /* -+ * Make lower_mnt R/O. That way fchmod/fchown on lower file -+ * will fail instead of modifying lower fs. -+ */ -+ ufs->lower_mnt->mnt_flags |= MNT_READONLY; -+ -+ /* If the upper fs is r/o, we mark overlayfs r/o too */ -+ if (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY) -+ sb->s_flags |= MS_RDONLY; -+ -+ if (!(sb->s_flags & MS_RDONLY)) { -+ err = mnt_want_write(ufs->upper_mnt); -+ if (err) -+ goto out_put_lower_mnt; -+ } -+ -+ err = -ENOMEM; -+ root_inode = ovl_new_inode(sb, S_IFDIR, oe); -+ if (!root_inode) -+ goto out_drop_write; -+ -+ root_dentry = d_make_root(root_inode); -+ if (!root_dentry) -+ goto out_drop_write; -+ -+ mntput(upperpath.mnt); -+ mntput(lowerpath.mnt); -+ -+ oe->__upperdentry = dget(upperpath.dentry); -+ oe->lowerdentry = lowerpath.dentry; -+ -+ root_dentry->d_fsdata = oe; -+ root_dentry->d_op = &ovl_dentry_operations; -+ -+ sb->s_magic = OVERLAYFS_SUPER_MAGIC; -+ sb->s_op = &ovl_super_operations; -+ sb->s_root = root_dentry; -+ sb->s_fs_info = ufs; -+ -+ return 0; -+ -+out_drop_write: -+ if (!(sb->s_flags & MS_RDONLY)) -+ mnt_drop_write(ufs->upper_mnt); -+out_put_lower_mnt: -+ mntput(ufs->lower_mnt); -+out_put_upper_mnt: -+ mntput(ufs->upper_mnt); -+out_put_lowerpath: -+ path_put(&lowerpath); -+out_put_upperpath: -+ path_put(&upperpath); -+out_free_oe: -+ kfree(oe); -+out_free_config: -+ kfree(ufs->config.lowerdir); -+ kfree(ufs->config.upperdir); -+out_free_ufs: -+ kfree(ufs); -+out: -+ return err; -+} -+ -+static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags, -+ const char *dev_name, void *raw_data) -+{ -+ return mount_nodev(fs_type, flags, raw_data, ovl_fill_super); -+} -+ -+static struct file_system_type ovl_fs_type = { -+ .owner = THIS_MODULE, -+ .name = "overlayfs", -+ .mount = ovl_mount, -+ .kill_sb = kill_anon_super, -+}; -+ -+static int __init ovl_init(void) -+{ -+ return register_filesystem(&ovl_fs_type); -+} -+ -+static void __exit ovl_exit(void) -+{ -+ unregister_filesystem(&ovl_fs_type); -+} -+ -+module_init(ovl_init); -+module_exit(ovl_exit); ---- a/fs/splice.c -+++ b/fs/splice.c -@@ -1307,6 +1307,7 @@ long do_splice_direct(struct file *in, l - - return ret; - } -+EXPORT_SYMBOL(do_splice_direct); - - static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, - struct pipe_inode_info *opipe, ---- a/include/linux/fs.h -+++ b/include/linux/fs.h -@@ -244,6 +244,12 @@ struct iattr { - */ - #include <linux/quota.h> - -+/* -+ * Maximum number of layers of fs stack. Needs to be limited to -+ * prevent kernel stack overflow -+ */ -+#define FILESYSTEM_MAX_STACK_DEPTH 2 -+ - /** - * enum positive_aop_returns - aop return codes with specific semantics - * -@@ -1320,6 +1326,11 @@ struct super_block { - - /* Being remounted read-only */ - int s_readonly_remount; -+ -+ /* -+ * Indicates how deep in a filesystem stack this SB is -+ */ -+ int s_stack_depth; - }; - - /* superblock cache pruning functions */ -@@ -1573,6 +1584,7 @@ struct inode_operations { - int (*atomic_open)(struct inode *, struct dentry *, - struct file *, unsigned open_flag, - umode_t create_mode, int *opened); -+ int (*dentry_open)(struct dentry *, struct file *, const struct cred *); - } ____cacheline_aligned; - - ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector, -@@ -2005,6 +2017,7 @@ extern struct file *file_open_name(struc - extern struct file *filp_open(const char *, int, umode_t); - extern struct file *file_open_root(struct dentry *, struct vfsmount *, - const char *, int); -+extern int vfs_open(const struct path *, struct file *, const struct cred *); - extern struct file * dentry_open(const struct path *, int, const struct cred *); - extern int filp_close(struct file *, fl_owner_t id); - -@@ -2210,6 +2223,7 @@ extern sector_t bmap(struct inode *, sec - #endif - extern int notify_change(struct dentry *, struct iattr *); - extern int inode_permission(struct inode *, int); -+extern int __inode_permission(struct inode *, int); - extern int generic_permission(struct inode *, int); - - static inline bool execute_ok(struct inode *inode) ---- a/include/linux/mount.h -+++ b/include/linux/mount.h -@@ -68,6 +68,9 @@ extern void mnt_pin(struct vfsmount *mnt - extern void mnt_unpin(struct vfsmount *mnt); - extern int __mnt_is_readonly(struct vfsmount *mnt); - -+struct path; -+extern struct vfsmount *clone_private_mount(struct path *path); -+ - struct file_system_type; - extern struct vfsmount *vfs_kern_mount(struct file_system_type *type, - int flags, const char *name, ---- a/MAINTAINERS -+++ b/MAINTAINERS -@@ -5666,6 +5666,13 @@ F: drivers/scsi/osd/ - F: include/scsi/osd_* - F: fs/exofs/ - -+OVERLAYFS FILESYSTEM -+M: Miklos Szeredi <miklos@szeredi.hu> -+L: linux-fsdevel@vger.kernel.org -+S: Supported -+F: fs/overlayfs/* -+F: Documentation/filesystems/overlayfs.txt -+ - P54 WIRELESS DRIVER - M: Christian Lamparter <chunkeey@googlemail.com> - L: linux-wireless@vger.kernel.org |