On Tue, Mar 19, 2024 at 09:45:56AM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> Unmapped buffers don't exist anymore, so the page straddling
> detection and slow path code can go away now.
>
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
Oh good, I was reading throguh this code just yesterday for other
reasons and now I'll just stop. :)
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
--D
> ---
> fs/xfs/xfs_buf_item.c | 124 ------------------------------------------
> 1 file changed, 124 deletions(-)
>
> diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
> index 7b66d3fe4ecd..cbc06605d31c 100644
> --- a/fs/xfs/xfs_buf_item.c
> +++ b/fs/xfs/xfs_buf_item.c
> @@ -56,31 +56,6 @@ 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_folio_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.
> @@ -97,11 +72,8 @@ 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)
> @@ -114,15 +86,6 @@ 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;
>
> @@ -137,43 +100,6 @@ 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++;
> - }
> - }
> }
>
> /*
> @@ -286,8 +212,6 @@ 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 */
> @@ -332,15 +256,6 @@ 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++;
> @@ -356,45 +271,6 @@ 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++;
> - }
> - }
> }
>
> /*
> --
> 2.43.0
>
>
