On Tue, Jun 21, 2011 at 8:24 AM, Lukas Czerner <lczerner@xxxxxxxxxx> wrote: > > On Mon, 20 Jun 2011, Jiaying Zhang wrote: > > > We have hit the same BUG_ON as described in > > https://bugzilla.kernel.org/show_bug.cgi?id=31222 > > on some of our servers that have disk failures or corrupted inodes. After > > looking at the code, I think the problem is that we are not freeing inode's > > preallocation list when check_eofblocks_fl fails in ext4_ext_map_blocks(), > > which leaves the inode's preallocation list in an inconsistent state. > > > > Below is a proposed patch to fix the bug. I have tested it by manually > > inserting a random failure in check_eofblocks_fl() and run a test that > > creates and uses an inode's preallocated blocks. Without the fix, the kernel > > crashes after a few runs. With the fix, no crash is observed. > > > > ext4: free allocated and pre-allocated blocks when check_eofblocks_fl fails > > > > Upon corrupted inode or disk failures, we may fail after we already allocate > > some blocks from the inode or take some blocks from the inode's preallocation > > list, but before we successfully insert the corresponding extent to the extent > > tree. In this case, we should free any allocated blocks and discard the inode's > > preallocated blocks because the entries in the inode's preallocation list may > > be in an inconsistent state. > > > > Signed-off-by: Jiaying Zhang <jiayingz@xxxxxxxxxx> > > Hi, > > the change looks good to me (with one note), but the patch itself is not very > well formated, and Ted would have to copy it out. Please use this: > > ext4: free allocated and pre-allocated blocks when check_eofblocks_fl fails > > for Subject line and put any comments which should not appear in the > commit description after signed-off-by line starting with "--- " line. > Or just use git format-patch. Thanks for the suggestion. I will re-send the patch with correct format. > > > > > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c > > index 5199bac..8cf6ec9 100644 > > --- a/fs/ext4/extents.c > > +++ b/fs/ext4/extents.c > > @@ -3596,10 +3596,8 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, > > } > > > > err = check_eofblocks_fl(handle, inode, map->m_lblk, path, ar.len); > > - if (err) > > - goto out2; > > - > > - err = ext4_ext_insert_extent(handle, inode, path, &newex, flags); > > + if (!err) > > + err = ext4_ext_insert_extent(handle, inode, path, &newex, flags); > > if (err) { > > why not to use: > else { > It is not the same. If there is an error from ext4_ext_insert_extent(), we also want to free allocated blocks. Jiaying > > > /* free data blocks we just allocated */ > > /* not a good idea to call discard here directly, > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > Thanks! > -Lukas -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
