| Message ID | 20140401233646.GA6549@wallace |
|---|---|
| State | Accepted, archived |
| Headers | show |
On Tue, Apr 01, 2014 at 07:36:46PM -0400, Eric Whitney wrote: > Xfstests generic/311 and shared/298 fail when run on a bigalloc file > system. Kernel error messages produced during the tests report that > blocks to be freed are already on the to-be-freed list. When e2fsck > is run at the end of the tests, it typically reports bad i_blocks and > bad free blocks counts. > > The bug that causes these failures is located in ext4_ext_rm_leaf(). > Code at the end of the function frees a partial cluster if it's not > shared with an extent remaining in the leaf. However, if all the > extents in the leaf have been removed, the code dereferences an > invalid extent pointer (off the front of the leaf) when the check for > sharing is made. This generally has the effect of unconditionally > freeing the partial cluster, which leads to the observed failures > when the partial cluster is shared with the last extent in the next > leaf. > > Fix this by attempting to free the cluster only if extents remain in > the leaf. Any remaining partial cluster will be freed if possible > when the next leaf is processed or when leaf removal is complete. > > Signed-off-by: Eric Whitney <enwlinux@gmail.com> Thanks, applied. I added a "Cc: stable@vger.kernel.org" for this patch. Cheers, - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 243a02e..340fadd 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -2743,10 +2743,15 @@ ext4_ext_rm_leaf(handle_t *handle, struct inode *inode, err = ext4_ext_correct_indexes(handle, inode, path); /* - * Free the partial cluster only if the current extent does not - * reference it. Otherwise we might free used cluster. + * If there's a partial cluster and at least one extent remains in + * the leaf, free the partial cluster if it isn't shared with the + * current extent. If there's a partial cluster and no extents + * remain in the leaf, it can't be freed here. It can only be + * freed when it's possible to determine if it's not shared with + * any other extent - when the next leaf is processed or when space + * removal is complete. */ - if (*partial_cluster > 0 && + if (*partial_cluster > 0 && eh->eh_entries && (EXT4_B2C(sbi, ext4_ext_pblock(ex) + ex_ee_len - 1) != *partial_cluster)) { int flags = get_default_free_blocks_flags(inode);
Xfstests generic/311 and shared/298 fail when run on a bigalloc file system. Kernel error messages produced during the tests report that blocks to be freed are already on the to-be-freed list. When e2fsck is run at the end of the tests, it typically reports bad i_blocks and bad free blocks counts. The bug that causes these failures is located in ext4_ext_rm_leaf(). Code at the end of the function frees a partial cluster if it's not shared with an extent remaining in the leaf. However, if all the extents in the leaf have been removed, the code dereferences an invalid extent pointer (off the front of the leaf) when the check for sharing is made. This generally has the effect of unconditionally freeing the partial cluster, which leads to the observed failures when the partial cluster is shared with the last extent in the next leaf. Fix this by attempting to free the cluster only if extents remain in the leaf. Any remaining partial cluster will be freed if possible when the next leaf is processed or when leaf removal is complete. Signed-off-by: Eric Whitney <enwlinux@gmail.com> --- fs/ext4/extents.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)