Re: [PATCH 10/18] xfs: simplify xfs_map_blocks by using xfs_iext_lookup_extent directly

Brian Foster
2018-05-31T13:46:53Z

On Wed, May 30, 2018 at 12:00:05PM +0200, Christoph Hellwig wrote:
> xfs_bmapi_read adds zero value in xfs_map_blocks. Replace it with a
> direct call to the low-level extent lookup function.
>
> Note that we now always pass a 0 length to the trace points as we ask
> for an unspecified len.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

> fs/xfs/xfs_aops.c | 19 +++++--------------
> 1 file changed, 5 insertions(+), 14 deletions(-)
>
> diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> index 587493e9c8a1..cef2bc3cf98b 100644
> --- a/fs/xfs/xfs_aops.c
> +++ b/fs/xfs/xfs_aops.c
> @@ -387,7 +387,6 @@ xfs_map_blocks(
> int whichfork = XFS_DATA_FORK;
> struct xfs_iext_cursor icur;
> int error = 0;
> - int nimaps = 1;
>
> if (XFS_FORCED_SHUTDOWN(mp))
> return -EIO;
> @@ -429,24 +428,16 @@ xfs_map_blocks(
> goto allocate_blocks;
> }
>
> - error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
> - imap, &nimaps, XFS_BMAPI_ENTIRE);
> + if (!xfs_iext_lookup_extent(ip, &ip->i_df, offset_fsb, &icur, imap))
> + imap->br_startoff = end_fsb; /* fake a hole past EOF */
> xfs_iunlock(ip, XFS_ILOCK_SHARED);
> - if (error)
> - return error;
>
> - if (!nimaps) {
> - /*
> - * Lookup returns no match? Beyond eof? regardless,
> - * return it as a hole so we don't write it
> - */
> + if (imap->br_startoff > offset_fsb) {
> + /* landed in a hole or beyond EOF */
> + imap->br_blockcount = imap->br_startoff - offset_fsb;
> imap->br_startoff = offset_fsb;
> - imap->br_blockcount = end_fsb - offset_fsb;
> imap->br_startblock = HOLESTARTBLOCK;
> *type = XFS_IO_HOLE;
> - } else if (imap->br_startblock == HOLESTARTBLOCK) {
> - /* landed in a hole */
> - *type = XFS_IO_HOLE;
> } else {
> if (isnullstartblock(imap->br_startblock)) {
> /* got a delalloc extent */