shinys000114/linux
1
0
Fork 0
mirror of https://github.com/hardkernel/linux.git synced 2026-06-05 02:21:52 +09:00
Code Issues Packages Projects Releases Wiki Activity

ext4: fix a potential fiemap/page fault deadlock w/ inline_data

Browse Source 
commit 2b08b1f12c upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Theodore Ts'o
2018-12-25 00:56:33 -05:00
committed by Greg Kroah-Hartman
parent eb13c60d82
commit b4727299f5
1 changed files with 3 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
fs/ext4/inline.c
View File

@@ -1864,12 +1864,12 @@ 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);
}