Messages in this thread | | | Date | Thu, 4 Oct 2012 22:55:28 +0100 | From | Ben Hutchings <> | Subject | Re: [ 110/180] ext4: dont let i_reserved_meta_blocks go negative |
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On Tue, Oct 02, 2012 at 12:53:47AM +0200, Willy Tarreau wrote: > 2.6.32-longterm review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Brian Foster <bfoster@redhat.com> > > commit 97795d2a5b8d3c8dc4365d4bd3404191840453ba upstream. > > 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. [...] > + 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; > + } [...]
This seems to be working around a bug elsewhere. Has the underlying bug been fixed in mainline yet?
Ben.
-- Ben Hutchings We get into the habit of living before acquiring the habit of thinking. - Albert Camus
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