Commit fd878516 authored by Dave Chinner's avatar Dave Chinner Committed by Carlos Maiolino
Browse files

xfs: buffer items don't straddle pages anymore 



Unmapped buffers don't exist anymore, so the page straddling
detection and slow path code can go away now.

Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
Signed-off-by: default avatarCarlos Maiolino <cem@kernel.org>
parent a2f790b2

fs/xfs/xfs_buf_item.c

+0 −124
Original line number Diff line number Diff line
@@ -57,31 +57,6 @@ xfs_buf_log_format_size( 
			(blfp->blf_map_size * sizeof(blfp->blf_data_map[0]));

}



/*

 * We only have to worry about discontiguous buffer range straddling on unmapped

 * buffers. Everything else will have a contiguous data region we can copy from.

 */

static inline bool

xfs_buf_item_straddle(

	struct xfs_buf		*bp,

	uint			offset,

	int			first_bit,

	int			nbits)

{

	void			*first, *last;



	if (bp->b_page_count == 1)

		return false;



	first = xfs_buf_offset(bp, offset + (first_bit << XFS_BLF_SHIFT));

	last = xfs_buf_offset(bp,

			offset + ((first_bit + nbits) << XFS_BLF_SHIFT));



	if (last - first != nbits * XFS_BLF_CHUNK)

		return true;

	return false;

}



/*

 * Return the number of log iovecs and space needed to log the given buf log

 * item segment.
@@ -98,11 +73,8 @@ xfs_buf_item_size_segment( 
	int				*nvecs,

	int				*nbytes)

{

	struct xfs_buf			*bp = bip->bli_buf;

	int				first_bit;

	int				nbits;

	int				next_bit;

	int				last_bit;



	first_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size, 0);

	if (first_bit == -1)
@@ -115,15 +87,6 @@ xfs_buf_item_size_segment( 
		nbits = xfs_contig_bits(blfp->blf_data_map,

					blfp->blf_map_size, first_bit);

		ASSERT(nbits > 0);



		/*

		 * Straddling a page is rare because we don't log contiguous

		 * chunks of unmapped buffers anywhere.

		 */

		if (nbits > 1 &&

		    xfs_buf_item_straddle(bp, offset, first_bit, nbits))

			goto slow_scan;



		(*nvecs)++;

		*nbytes += nbits * XFS_BLF_CHUNK;
@@ -138,43 +101,6 @@ xfs_buf_item_size_segment( 
	} while (first_bit != -1);



	return;



slow_scan:

	ASSERT(bp->b_addr == NULL);

	last_bit = first_bit;

	nbits = 1;

	while (last_bit != -1) {



		*nbytes += XFS_BLF_CHUNK;



		/*

		 * This takes the bit number to start looking from and

		 * returns the next set bit from there.  It returns -1

		 * if there are no more bits set or the start bit is

		 * beyond the end of the bitmap.

		 */

		next_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size,

					last_bit + 1);

		/*

		 * If we run out of bits, leave the loop,

		 * else if we find a new set of bits bump the number of vecs,

		 * else keep scanning the current set of bits.

		 */

		if (next_bit == -1) {

			if (first_bit != last_bit)

				(*nvecs)++;

			break;

		} else if (next_bit != last_bit + 1 ||

		           xfs_buf_item_straddle(bp, offset, first_bit, nbits)) {

			last_bit = next_bit;

			first_bit = next_bit;

			(*nvecs)++;

			nbits = 1;

		} else {

			last_bit++;

			nbits++;

		}

	}

}



/*
@@ -287,8 +213,6 @@ xfs_buf_item_format_segment( 
	struct xfs_buf		*bp = bip->bli_buf;

	uint			base_size;

	int			first_bit;

	int			last_bit;

	int			next_bit;

	uint			nbits;



	/* copy the flags across from the base format item */
@@ -333,15 +257,6 @@ xfs_buf_item_format_segment( 
		nbits = xfs_contig_bits(blfp->blf_data_map,

					blfp->blf_map_size, first_bit);

		ASSERT(nbits > 0);



		/*

		 * Straddling a page is rare because we don't log contiguous

		 * chunks of unmapped buffers anywhere.

		 */

		if (nbits > 1 &&

		    xfs_buf_item_straddle(bp, offset, first_bit, nbits))

			goto slow_scan;



		xfs_buf_item_copy_iovec(lv, vecp, bp, offset,

					first_bit, nbits);

		blfp->blf_size++;
@@ -357,45 +272,6 @@ xfs_buf_item_format_segment( 
	} while (first_bit != -1);



	return;



slow_scan:

	ASSERT(bp->b_addr == NULL);

	last_bit = first_bit;

	nbits = 1;

	for (;;) {

		/*

		 * This takes the bit number to start looking from and

		 * returns the next set bit from there.  It returns -1

		 * if there are no more bits set or the start bit is

		 * beyond the end of the bitmap.

		 */

		next_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size,

					(uint)last_bit + 1);

		/*

		 * If we run out of bits fill in the last iovec and get out of

		 * the loop.  Else if we start a new set of bits then fill in

		 * the iovec for the series we were looking at and start

		 * counting the bits in the new one.  Else we're still in the

		 * same set of bits so just keep counting and scanning.

		 */

		if (next_bit == -1) {

			xfs_buf_item_copy_iovec(lv, vecp, bp, offset,

						first_bit, nbits);

			blfp->blf_size++;

			break;

		} else if (next_bit != last_bit + 1 ||

		           xfs_buf_item_straddle(bp, offset, first_bit, nbits)) {

			xfs_buf_item_copy_iovec(lv, vecp, bp, offset,

						first_bit, nbits);

			blfp->blf_size++;

			first_bit = next_bit;

			last_bit = next_bit;

			nbits = 1;

		} else {

			last_bit++;

			nbits++;

		}

	}

}



/*