Commit 5c5b6f75 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Darrick J. Wong
Browse files

xfs: cleanup xfs_direct_write_iomap_begin 



Move more checks into the helpers that determine if we need a COW
operation or allocation and split the return path for when an existing
data for allocation has been found versus a new allocation.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
parent 12dfb58a

fs/xfs/xfs_iomap.c

+46 −42
Original line number Diff line number Diff line
@@ -642,23 +642,42 @@ xfs_iomap_write_unwritten( 
static inline bool

imap_needs_alloc(

	struct inode		*inode,

	unsigned		flags,

	struct xfs_bmbt_irec	*imap,

	int			nimaps)

{

	return !nimaps ||

	/* don't allocate blocks when just zeroing */

	if (flags & IOMAP_ZERO)

		return false;

	if (!nimaps ||

	    imap->br_startblock == HOLESTARTBLOCK ||

		imap->br_startblock == DELAYSTARTBLOCK ||

		(IS_DAX(inode) && imap->br_state == XFS_EXT_UNWRITTEN);

	    imap->br_startblock == DELAYSTARTBLOCK)

		return true;

	/* we convert unwritten extents before copying the data for DAX */

	if (IS_DAX(inode) && imap->br_state == XFS_EXT_UNWRITTEN)

		return true;

	return false;

}



static inline bool

needs_cow_for_zeroing(

imap_needs_cow(

	struct xfs_inode	*ip,

	unsigned int		flags,

	struct xfs_bmbt_irec	*imap,

	int			nimaps)

{

	return nimaps &&

		imap->br_startblock != HOLESTARTBLOCK &&

		imap->br_state != XFS_EXT_UNWRITTEN;

	if (!xfs_is_cow_inode(ip))

		return false;



	/* when zeroing we don't have to COW holes or unwritten extents */

	if (flags & IOMAP_ZERO) {

		if (!nimaps ||

		    imap->br_startblock == HOLESTARTBLOCK ||

		    imap->br_state == XFS_EXT_UNWRITTEN)

			return false;

	}



	return true;

}



static int
@@ -742,6 +761,14 @@ xfs_direct_write_iomap_begin( 
	if (XFS_FORCED_SHUTDOWN(mp))

		return -EIO;



	/*

	 * Writes that span EOF might trigger an IO size update on completion,

	 * so consider them to be dirty for the purposes of O_DSYNC even if

	 * there is no other metadata changes pending or have been made here.

	 */

	if (offset + length > i_size_read(inode))

		iomap_flags |= IOMAP_F_DIRTY;



	/*

	 * Lock the inode in the manner required for the specified operation and

	 * check for as many conditions that would result in blocking as
@@ -761,12 +788,7 @@ xfs_direct_write_iomap_begin( 
	 * Break shared extents if necessary. Checks for non-blocking IO have

	 * been done up front, so we don't need to do them here.

	 */

	if (xfs_is_cow_inode(ip)) {

		/* if zeroing doesn't need COW allocation, then we are done. */

		if ((flags & IOMAP_ZERO) &&

		    !needs_cow_for_zeroing(&imap, nimaps))

			goto out_found;



	if (imap_needs_cow(ip, flags, &imap, nimaps)) {

		/* may drop and re-acquire the ilock */

		error = xfs_reflink_allocate_cow(ip, &imap, &cmap, &shared,

				&lockmode, flags & IOMAP_DIRECT);
@@ -778,18 +800,17 @@ xfs_direct_write_iomap_begin( 
		length = XFS_FSB_TO_B(mp, end_fsb) - offset;

	}



	/* Don't need to allocate over holes when doing zeroing operations. */

	if (flags & IOMAP_ZERO)

		goto out_found;

	if (imap_needs_alloc(inode, flags, &imap, nimaps))

		goto allocate_blocks;



	if (!imap_needs_alloc(inode, &imap, nimaps))

		goto out_found;

	xfs_iunlock(ip, lockmode);

	trace_xfs_iomap_found(ip, offset, length, XFS_DATA_FORK, &imap);

	return xfs_bmbt_to_iomap(ip, iomap, &imap, iomap_flags);



	/* If nowait is set bail since we are going to make allocations. */

	if (flags & IOMAP_NOWAIT) {

allocate_blocks:

	error = -EAGAIN;

	if (flags & IOMAP_NOWAIT)

		goto out_unlock;

	}



	/*

	 * We cap the maximum length we map to a sane size  to keep the chunks
@@ -808,29 +829,12 @@ xfs_direct_write_iomap_begin( 
	 */

	if (lockmode == XFS_ILOCK_EXCL)

		xfs_ilock_demote(ip, lockmode);

	error = xfs_iomap_write_direct(ip, offset, length, &imap,

			nimaps);

	error = xfs_iomap_write_direct(ip, offset, length, &imap, nimaps);

	if (error)

		return error;



	iomap_flags |= IOMAP_F_NEW;

	trace_xfs_iomap_alloc(ip, offset, length, XFS_DATA_FORK, &imap);



out_finish:

	/*

	 * Writes that span EOF might trigger an IO size update on completion,

	 * so consider them to be dirty for the purposes of O_DSYNC even if

	 * there is no other metadata changes pending or have been made here.

	 */

	if (offset + length > i_size_read(inode))

		iomap_flags |= IOMAP_F_DIRTY;

	return xfs_bmbt_to_iomap(ip, iomap, &imap, iomap_flags);



out_found:

	ASSERT(nimaps);

	xfs_iunlock(ip, lockmode);

	trace_xfs_iomap_found(ip, offset, length, XFS_DATA_FORK, &imap);

	goto out_finish;

	return xfs_bmbt_to_iomap(ip, iomap, &imap, iomap_flags | IOMAP_F_NEW);



out_found_cow:

	xfs_iunlock(ip, lockmode);