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ext4: protect group inode free counting with group lock

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Now when we set the group inode free count, we don't have a proper
group lock so that multiple threads may decrease the inode free
count at the same time. And e2fsck will complain something like:

Free inodes count wrong for group #1 (1, counted=0).
Fix? no

Free inodes count wrong for group #2 (3, counted=0).
Fix? no

Directories count wrong for group #2 (780, counted=779).
Fix? no

Free inodes count wrong for group #3 (2272, counted=2273).
Fix? no

So this patch try to protect it with the ext4_lock_group.

btw, it is found by xfstests test case 269 and the volume is
mkfsed with the parameter
"-O ^resize_inode,^uninit_bg,extent,meta_bg,flex_bg,ext_attr"
and I have run it 100 times and the error in e2fsck doesn't
show up again.

Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Tao Ma 2012-05-28 18:20:59 -04:00 committed by Theodore Ts'o
parent 8563000d3b
commit 6f2e9f0e7d
1 changed files with 4 additions and 1 deletions
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5
fs/ext4/ialloc.c
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@ -797,7 +797,10 @@ struct inode *ext4_new_inode(handle_t *handle, struct inode *dir, umode_t mode,
ext4_itable_unused_set(sb, gdp,
(EXT4_INODES_PER_GROUP(sb) - ino));
up_read(&grp->alloc_sem);
} else {
ext4_lock_group(sb, group);
}
ext4_free_inodes_set(sb, gdp, ext4_free_inodes_count(sb, gdp) - 1);
if (S_ISDIR(mode)) {
ext4_used_dirs_set(sb, gdp, ext4_used_dirs_count(sb, gdp) + 1);
@ -811,8 +814,8 @@ struct inode *ext4_new_inode(handle_t *handle, struct inode *dir, umode_t mode,
ext4_inode_bitmap_csum_set(sb, group, gdp, inode_bitmap_bh,
EXT4_INODES_PER_GROUP(sb) / 8);
ext4_group_desc_csum_set(sb, group, gdp);
ext4_unlock_group(sb, group);
}
ext4_unlock_group(sb, group);
BUFFER_TRACE(inode_bitmap_bh, "call ext4_handle_dirty_metadata");
err = ext4_handle_dirty_metadata(handle, NULL, inode_bitmap_bh);