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| author |   Theodore Ts'o <tytso@mit.edu> | 2017-10-06 23:09:55 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2017-10-06 23:09:55 -0400 |
| commit | 51e3ae81ec58e95f10a98ef3dd6d7bce5d8e35a2 (patch) | |
| tree | 5c21c3be3e1f1c40c2659ff8779232efad912c5b /fs/ext4 | |
| parent | ext4: retry allocations conservatively (diff) | |
| download | linux-dev-51e3ae81ec58e95f10a98ef3dd6d7bce5d8e35a2.tar.xz linux-dev-51e3ae81ec58e95f10a98ef3dd6d7bce5d8e35a2.zip | |
ext4: fix interaction between i_size, fallocate, and delalloc after a crash
If there are pending writes subject to delayed allocation, then i_size
will show size after the writes have completed, while i_disksize
contains the value of i_size on the disk (since the writes have not
been persisted to disk).
If fallocate(2) is called with the FALLOC_FL_KEEP_SIZE flag, either
with or without the FALLOC_FL_ZERO_RANGE flag set, and the new size
after the fallocate(2) is between i_size and i_disksize, then after a
crash, if a journal commit has resulted in the changes made by the
fallocate() call to be persisted after a crash, but the delayed
allocation write has not resolved itself, i_size would not be updated,
and this would cause the following e2fsck complaint:
Inode 12, end of extent exceeds allowed value
(logical block 33, physical block 33441, len 7)
This can only take place on a sparse file, where the fallocate(2) call
is allocating blocks in a range which is before a pending delayed
allocation write which is extending i_size. Since this situation is
quite rare, and the window in which the crash must take place is
typically < 30 seconds, in practice this condition will rarely happen.
Nevertheless, it can be triggered in testing, and in particular by
xfstests generic/456.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reported-by: Amir Goldstein <amir73il@gmail.com>
Cc: stable@vger.kernel.org
Diffstat (limited to 'fs/ext4')
| -rw-r--r-- | fs/ext4/extents.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 97f0fd06728d..07bca11749d4 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -4794,7 +4794,8 @@ static long ext4_zero_range(struct file *file, loff_t offset, } if (!(mode & FALLOC_FL_KEEP_SIZE) && - offset + len > i_size_read(inode)) { + (offset + len > i_size_read(inode) || + offset + len > EXT4_I(inode)->i_disksize)) { new_size = offset + len; ret = inode_newsize_ok(inode, new_size); if (ret) @@ -4965,7 +4966,8 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len) } if (!(mode & FALLOC_FL_KEEP_SIZE) && - offset + len > i_size_read(inode)) { + (offset + len > i_size_read(inode) || + offset + len > EXT4_I(inode)->i_disksize)) { new_size = offset + len; ret = inode_newsize_ok(inode, new_size); if (ret) |