diff options
Diffstat (limited to 'target/linux')
| -rw-r--r-- | target/linux/generic/backport-4.14/500-ubifs-Handle-re-linking-of-inodes-correctly-while-re.patch | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/target/linux/generic/backport-4.14/500-ubifs-Handle-re-linking-of-inodes-correctly-while-re.patch b/target/linux/generic/backport-4.14/500-ubifs-Handle-re-linking-of-inodes-correctly-while-re.patch new file mode 100644 index 0000000000..71e036c920 --- /dev/null +++ b/target/linux/generic/backport-4.14/500-ubifs-Handle-re-linking-of-inodes-correctly-while-re.patch @@ -0,0 +1,89 @@ +From: Richard Weinberger <richard@nod.at> +Date: Wed, 7 Nov 2018 23:04:43 +0100 +Subject: [PATCH] ubifs: Handle re-linking of inodes correctly while recovery +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +UBIFS's recovery code strictly assumes that a deleted inode will never +come back, therefore it removes all data which belongs to that inode +as soon it faces an inode with link count 0 in the replay list. +Before O_TMPFILE this assumption was perfectly fine. With O_TMPFILE +it can lead to data loss upon a power-cut. + +Consider a journal with entries like: +0: inode X (nlink = 0) /* O_TMPFILE was created */ +1: data for inode X /* Someone writes to the temp file */ +2: inode X (nlink = 0) /* inode was changed, xattr, chmod, … */ +3: inode X (nlink = 1) /* inode was re-linked via linkat() */ + +Upon replay of entry #2 UBIFS will drop all data that belongs to inode X, +this will lead to an empty file after mounting. + +As solution for this problem, scan the replay list for a re-link entry +before dropping data. + +Fixes: 474b93704f32 ("ubifs: Implement O_TMPFILE") +Cc: stable@vger.kernel.org +Cc: Russell Senior <russell@personaltelco.net> +Cc: Rafał Miłecki <zajec5@gmail.com> +Reported-by: Russell Senior <russell@personaltelco.net> +Reported-by: Rafał Miłecki <zajec5@gmail.com> +Signed-off-by: Richard Weinberger <richard@nod.at> +--- + fs/ubifs/replay.c | 37 +++++++++++++++++++++++++++++++++++++ + 1 file changed, 37 insertions(+) + +--- a/fs/ubifs/replay.c ++++ b/fs/ubifs/replay.c +@@ -210,6 +210,38 @@ static int trun_remove_range(struct ubif + } + + /** ++ * inode_still_linked - check whether inode in question will be re-linked. ++ * @c: UBIFS file-system description object ++ * @rino: replay entry to test ++ * ++ * O_TMPFILE files can be re-linked, this means link count goes from 0 to 1. ++ * This case needs special care, otherwise all references to the inode will ++ * be removed upon the first replay entry of an inode with link count 0 ++ * is found. ++ */ ++static bool inode_still_linked(struct ubifs_info *c, struct replay_entry *rino) ++{ ++ struct replay_entry *r; ++ ++ ubifs_assert(rino->deletion); ++ ubifs_assert(key_type(c, &rino->key) == UBIFS_INO_KEY); ++ ++ /* ++ * Find the most recent entry for the inode behind @rino and check ++ * whether it is a deletion. ++ */ ++ list_for_each_entry_reverse(r, &c->replay_list, list) { ++ ubifs_assert(r->sqnum >= rino->sqnum); ++ if (key_inum(c, &r->key) == key_inum(c, &rino->key)) ++ return r->deletion == 0; ++ ++ } ++ ++ ubifs_assert(0); ++ return false; ++} ++ ++/** + * apply_replay_entry - apply a replay entry to the TNC. + * @c: UBIFS file-system description object + * @r: replay entry to apply +@@ -239,6 +271,11 @@ static int apply_replay_entry(struct ubi + { + ino_t inum = key_inum(c, &r->key); + ++ if (inode_still_linked(c, r)) { ++ err = 0; ++ break; ++ } ++ + err = ubifs_tnc_remove_ino(c, inum); + break; + } |