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authorBrian Foster <bfoster@redhat.com>2012-07-22 23:59:40 -0400
committerTheodore Ts'o <tytso@mit.edu>2012-07-22 23:59:40 -0400
commit97795d2a5b8d3c8dc4365d4bd3404191840453ba (patch)
tree75d5871a8ae658b05cdbe3c15d50c95694f8c79f
parent968dee77220768a5f52cf8b21d0bdb73486febef (diff)
downloadop-kernel-dev-97795d2a5b8d3c8dc4365d4bd3404191840453ba.zip
op-kernel-dev-97795d2a5b8d3c8dc4365d4bd3404191840453ba.tar.gz
ext4: don't let i_reserved_meta_blocks go negative
If we hit a condition where we have allocated metadata blocks that were not appropriately reserved, we risk underflow of ei->i_reserved_meta_blocks. In turn, this can throw sbi->s_dirtyclusters_counter significantly out of whack and undermine the nondelalloc fallback logic in ext4_nonda_switch(). Warn if this occurs and set i_allocated_meta_blocks to avoid this problem. This condition is reproduced by xfstests 270 against ext2 with delalloc enabled: Mar 28 08:58:02 localhost kernel: [ 171.526344] EXT4-fs (loop1): delayed block allocation failed for inode 14 at logical offset 64486 with max blocks 64 with error -28 Mar 28 08:58:02 localhost kernel: [ 171.526346] EXT4-fs (loop1): This should not happen!! Data will be lost 270 ultimately fails with an inconsistent filesystem and requires an fsck to repair. The cause of the error is an underflow in ext4_da_update_reserve_space() due to an unreserved meta block allocation. Signed-off-by: Brian Foster <bfoster@redhat.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: stable@vger.kernel.org
-rw-r--r--fs/ext4/inode.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index a533a18..25f809d 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -346,6 +346,15 @@ void ext4_da_update_reserve_space(struct inode *inode,
used = ei->i_reserved_data_blocks;
}
+ if (unlikely(ei->i_allocated_meta_blocks > ei->i_reserved_meta_blocks)) {
+ ext4_msg(inode->i_sb, KERN_NOTICE, "%s: ino %lu, allocated %d "
+ "with only %d reserved metadata blocks\n", __func__,
+ inode->i_ino, ei->i_allocated_meta_blocks,
+ ei->i_reserved_meta_blocks);
+ WARN_ON(1);
+ ei->i_allocated_meta_blocks = ei->i_reserved_meta_blocks;
+ }
+
/* Update per-inode reservations */
ei->i_reserved_data_blocks -= used;
ei->i_reserved_meta_blocks -= ei->i_allocated_meta_blocks;
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