diff options
| author | Salman Qazi <sqazi@google.com> | 2012-05-31 23:52:14 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2012-05-31 23:52:14 -0400 |
| commit | 95599968d19db175829fb580baa6b68939b320fb (patch) | |
| tree | f28bdf3d19f818a8d61dc68454c72d62e8247b05 /fs/ext4/mballoc.c | |
| parent | 02b7831019ea4e7994968c84b5826fa8b248ffc8 (diff) | |
| download | lwn-95599968d19db175829fb580baa6b68939b320fb.tar.gz lwn-95599968d19db175829fb580baa6b68939b320fb.zip | |
ext4: remove mb_groups before tearing down the buddy_cache
We can't have references held on pages in the s_buddy_cache while we are
trying to truncate its pages and put the inode. All the pages must be
gone before we reach clear_inode. This can only be gauranteed if we
can prevent new users from grabbing references to s_buddy_cache's pages.
The original bug can be reproduced and the bug fix can be verified by:
while true; do mount -t ext4 /dev/ram0 /export/hda3/ram0; \
umount /export/hda3/ram0; done &
while true; do cat /proc/fs/ext4/ram0/mb_groups; done
Signed-off-by: Salman Qazi <sqazi@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
Diffstat (limited to 'fs/ext4/mballoc.c')
| -rw-r--r-- | fs/ext4/mballoc.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 3d9277c48bc8..1cd6994fc446 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -2517,6 +2517,9 @@ int ext4_mb_release(struct super_block *sb) struct ext4_sb_info *sbi = EXT4_SB(sb); struct kmem_cache *cachep = get_groupinfo_cache(sb->s_blocksize_bits); + if (sbi->s_proc) + remove_proc_entry("mb_groups", sbi->s_proc); + if (sbi->s_group_info) { for (i = 0; i < ngroups; i++) { grinfo = ext4_get_group_info(sb, i); @@ -2564,8 +2567,6 @@ int ext4_mb_release(struct super_block *sb) } free_percpu(sbi->s_locality_groups); - if (sbi->s_proc) - remove_proc_entry("mb_groups", sbi->s_proc); return 0; } |