On Fri 28-09-12 19:44:03, Dmitry Monakhov wrote:
> ext4_set_io_unwritten_flag() will increment i_unwritten counter, so
> once we mark end_io with EXT4_END_IO_UNWRITTEN we have to revert it back
> on error path.
>
> - add missed error checks to prevent counter leakage
> - ext4_end_io_nolock() will clear EXT4_END_IO_UNWRITTEN flag to signal
> that conversion finished.
> - add BUG_ON to ext4_free_end_io() to prevent similar leakage in future.
>
> Visible effect of this bug is that unaligned aio_stress may deadlock
Looks good. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
>
> Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
> ---
> fs/ext4/extents.c | 21 ++++++++++++++-------
> fs/ext4/page-io.c | 6 +++++-
> 2 files changed, 19 insertions(+), 8 deletions(-)
>
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index e9549f9..69e2d13 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -3545,6 +3545,8 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
> if ((flags & EXT4_GET_BLOCKS_PRE_IO)) {
> ret = ext4_split_unwritten_extents(handle, inode, map,
> path, flags);
> + if (ret <= 0)
> + goto out;
> /*
> * Flag the inode(non aio case) or end_io struct (aio case)
> * that this IO needs to conversion to written when IO is
> @@ -3790,6 +3792,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
> struct ext4_allocation_request ar;
> ext4_io_end_t *io = ext4_inode_aio(inode);
> ext4_lblk_t cluster_offset;
> + int set_unwritten = 0;
>
> ext_debug("blocks %u/%u requested for inode %lu\n",
> map->m_lblk, map->m_len, inode->i_ino);
> @@ -4012,13 +4015,8 @@ got_allocated_blocks:
> * For non asycn direct IO case, flag the inode state
> * that we need to perform conversion when IO is done.
> */
> - if ((flags & EXT4_GET_BLOCKS_PRE_IO)) {
> - if (io)
> - ext4_set_io_unwritten_flag(inode, io);
> - else
> - ext4_set_inode_state(inode,
> - EXT4_STATE_DIO_UNWRITTEN);
> - }
> + if ((flags & EXT4_GET_BLOCKS_PRE_IO))
> + set_unwritten = 1;
> if (ext4_should_dioread_nolock(inode))
> map->m_flags |= EXT4_MAP_UNINIT;
> }
> @@ -4030,6 +4028,15 @@ got_allocated_blocks:
> if (!err)
> err = ext4_ext_insert_extent(handle, inode, path,
> &newex, flags);
> +
> + if (!err && set_unwritten) {
> + if (io)
> + ext4_set_io_unwritten_flag(inode, io);
> + else
> + ext4_set_inode_state(inode,
> + EXT4_STATE_DIO_UNWRITTEN);
> + }
> +
> if (err && free_on_err) {
> int fb_flags = flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE ?
> EXT4_FREE_BLOCKS_NO_QUOT_UPDATE : 0;
> diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
> index de77e31..9970022 100644
> --- a/fs/ext4/page-io.c
> +++ b/fs/ext4/page-io.c
> @@ -71,6 +71,8 @@ void ext4_free_io_end(ext4_io_end_t *io)
> int i;
>
> BUG_ON(!io);
> + BUG_ON(io->flag & EXT4_IO_END_UNWRITTEN);
> +
> if (io->page)
> put_page(io->page);
> for (i = 0; i < io->num_io_pages; i++)
> @@ -94,6 +96,8 @@ int ext4_end_io_nolock(ext4_io_end_t *io)
> ssize_t size = io->size;
> int ret = 0;
>
> + BUG_ON(!(io->flag & EXT4_IO_END_UNWRITTEN));
> +
> ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
> "list->prev 0x%p\n",
> io, inode->i_ino, io->list.next, io->list.prev);
> @@ -106,7 +110,7 @@ int ext4_end_io_nolock(ext4_io_end_t *io)
> "(inode %lu, offset %llu, size %zd, error %d)",
> inode->i_ino, offset, size, ret);
> }
> -
> + io->flag &= ~EXT4_IO_END_UNWRITTEN;
> if (io->iocb)
> aio_complete(io->iocb, io->result, 0);
>
> --
> 1.7.7.6
>
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