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| author | Theodore Ts'o <tytso@mit.edu> | 2018-12-25 00:56:33 -0500 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2018-12-25 00:56:33 -0500 |
| commit | 2b08b1f12cd664dc7d5c84ead9ff25ae97ad5491 (patch) | |
| tree | ec4e19afec1556c8aeecef9a460a1208c1a71c83 | |
| parent | 812c0cab2c0dfad977605dbadf9148490ca5d93f (diff) | |
| download | linux-2b08b1f12cd664dc7d5c84ead9ff25ae97ad5491.tar.gz linux-2b08b1f12cd664dc7d5c84ead9ff25ae97ad5491.tar.bz2 linux-2b08b1f12cd664dc7d5c84ead9ff25ae97ad5491.zip | |
ext4: fix a potential fiemap/page fault deadlock w/ inline_data
The ext4_inline_data_fiemap() function calls fiemap_fill_next_extent()
while still holding the xattr semaphore. This is not necessary and it
triggers a circular lockdep warning. This is because
fiemap_fill_next_extent() could trigger a page fault when it writes
into page which triggers a page fault. If that page is mmaped from
the inline file in question, this could very well result in a
deadlock.
This problem can be reproduced using generic/519 with a file system
configuration which has the inline_data feature enabled.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
| -rw-r--r-- | fs/ext4/inline.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c index 27373d88b5f0..56f6e1782d5f 100644 --- a/fs/ext4/inline.c +++ b/fs/ext4/inline.c @@ -1890,12 +1890,12 @@ int ext4_inline_data_fiemap(struct inode *inode, physical += (char *)ext4_raw_inode(&iloc) - iloc.bh->b_data; physical += offsetof(struct ext4_inode, i_block); - if (physical) - error = fiemap_fill_next_extent(fieinfo, start, physical, - inline_len, flags); brelse(iloc.bh); out: up_read(&EXT4_I(inode)->xattr_sem); + if (physical) + error = fiemap_fill_next_extent(fieinfo, start, physical, + inline_len, flags); return (error < 0 ? error : 0); } |