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Commit 8ff2957d authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Alex Elder
Browse files

xfs: simplify xfs_map_blocks 



No need to lock the extent map exclusive when performing an
overwrite, we know the extent map must already have been loaded by
get_blocks.  Apply the non-blocking inode semantics to all mapping
types instead of just delayed allocations.  Remove the handling of
not yet allocated blocks for the IO_UNWRITTEN case - if an extent is
marked as unwritten allocated in the buffer it must already have an
extent on disk.

Add asserts to verify all the assumptions above in debug builds.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
Signed-off-by: default avatarAlex Elder <aelder@sgi.com>
parent a206c817

fs/xfs/linux-2.6/xfs_aops.c

+25 −52
Original line number Diff line number Diff line
@@ -313,81 +313,54 @@ xfs_map_blocks( 
	struct xfs_mount	*mp = ip->i_mount;

	xfs_fileoff_t		offset_fsb, end_fsb;

	int			error = 0;

	int			lockmode = 0;

	int			bmapi_flags = XFS_BMAPI_ENTIRE;

	int			nimaps = 1;



	if (XFS_FORCED_SHUTDOWN(mp))

		return -XFS_ERROR(EIO);



	switch (type) {

	case IO_OVERWRITE:

		lockmode = xfs_ilock_map_shared(ip);

		break;

	case IO_UNWRITTEN:

		lockmode = XFS_ILOCK_EXCL;

	if (type == IO_UNWRITTEN)

		bmapi_flags |= XFS_BMAPI_IGSTATE;

		xfs_ilock(ip, lockmode);

		break;

	case IO_DELALLOC:

		lockmode = XFS_ILOCK_SHARED;



		if (!xfs_ilock_nowait(ip, lockmode)) {

	if (!xfs_ilock_nowait(ip, XFS_ILOCK_SHARED)) {

		if (nonblocking)

			return -XFS_ERROR(EAGAIN);

			xfs_ilock(ip, lockmode);

		}

		break;

		xfs_ilock(ip, XFS_ILOCK_SHARED);

	}



	ASSERT(ip->i_d.di_format != XFS_DINODE_FMT_BTREE ||

	       (ip->i_df.if_flags & XFS_IFEXTENTS));

	ASSERT(offset <= mp->m_maxioffset);



	if (offset + count > mp->m_maxioffset)

		count = mp->m_maxioffset - offset;

	end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);

	offset_fsb = XFS_B_TO_FSBT(mp, offset);



	error = xfs_bmapi(NULL, ip, offset_fsb, end_fsb - offset_fsb,

			  bmapi_flags,  NULL, 0, imap, &nimaps, NULL);

	xfs_iunlock(ip, XFS_ILOCK_SHARED);



	if (error)

		goto out;



	switch (type) {

	case IO_UNWRITTEN:

		/* If we found an extent, return it */

		if (nimaps &&

		    (imap->br_startblock != HOLESTARTBLOCK) &&

		    (imap->br_startblock != DELAYSTARTBLOCK)) {

			trace_xfs_map_blocks_found(ip, offset, count, type, imap);

			break;

		}

		return -XFS_ERROR(error);



		error = xfs_iomap_write_delay(ip, offset, count, imap);

	if (type == IO_DELALLOC &&

	    (!nimaps || isnullstartblock(imap->br_startblock))) {

		error = xfs_iomap_write_allocate(ip, offset, count, imap);

		if (!error)

			trace_xfs_map_blocks_alloc(ip, offset, count, type, imap);

		break;

	case IO_DELALLOC:

		/* If we found an extent, return it */

		xfs_iunlock(ip, lockmode);

		lockmode = 0;



		if (nimaps && !isnullstartblock(imap->br_startblock)) {

			trace_xfs_map_blocks_found(ip, offset, count, type, imap);

			break;

		return -XFS_ERROR(error);

	}



		error = xfs_iomap_write_allocate(ip, offset, count, imap);

		if (!error)

			trace_xfs_map_blocks_alloc(ip, offset, count, type, imap);

		break;

	default:

#ifdef DEBUG

	if (type == IO_UNWRITTEN) {

		ASSERT(nimaps);

		ASSERT(imap->br_startblock != HOLESTARTBLOCK);

		ASSERT(imap->br_startblock != DELAYSTARTBLOCK);

	}

#endif

	if (nimaps)

		trace_xfs_map_blocks_found(ip, offset, count, type, imap);

	}



out:

	if (lockmode)

		xfs_iunlock(ip, lockmode);

	return -XFS_ERROR(error);

	return 0;

}



STATIC int