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xfs: merge xfs_buf_find() and xfs_buf_get_map()
Now that we factored xfs_buf_find(), we can start separating into distinct fast and slow paths from xfs_buf_get_map(). We start by moving the lookup map and perag setup to _get_map(), and then move all the specifics of the fast path lookup into xfs_buf_lookup() and call it directly from _get_map(). We the move all the slow path code to xfs_buf_find_insert(), which is now also called directly from _get_map(). As such, xfs_buf_find() now goes away. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
This commit is contained in:
Dave Chinner
Dave Chinner
parent
de67dc5754
commit
348000804a
230
fs/xfs/xfs_buf.c
230
fs/xfs/xfs_buf.c
@ -537,7 +537,6 @@ xfs_buf_find_lock(
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if (!xfs_buf_trylock(bp)) {
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if (flags & XBF_TRYLOCK) {
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XFS_STATS_INC(bp->b_mount, xb_busy_locked);
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xfs_buf_rele(bp);
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return -EAGAIN;
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}
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xfs_buf_lock(bp);
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@ -557,144 +556,57 @@ xfs_buf_find_lock(
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return 0;
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}
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static inline struct xfs_buf *
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static inline int
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xfs_buf_lookup(
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struct xfs_perag *pag,
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struct xfs_buf_map *map)
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struct xfs_buf_map *map,
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xfs_buf_flags_t flags,
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struct xfs_buf **bpp)
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{
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struct xfs_buf *bp;
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int error;
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spin_lock(&pag->pag_buf_lock);
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bp = rhashtable_lookup(&pag->pag_buf_hash, map, xfs_buf_hash_params);
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if (!bp)
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return NULL;
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if (!bp) {
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spin_unlock(&pag->pag_buf_lock);
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return -ENOENT;
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}
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atomic_inc(&bp->b_hold);
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return bp;
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spin_unlock(&pag->pag_buf_lock);
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error = xfs_buf_find_lock(bp, flags);
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if (error) {
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xfs_buf_rele(bp);
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return error;
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}
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trace_xfs_buf_find(bp, flags, _RET_IP_);
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*bpp = bp;
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return 0;
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}
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/*
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* Insert the new_bp into the hash table. This consumes the perag reference
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* taken for the lookup.
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* taken for the lookup regardless of the result of the insert.
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*/
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static int
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xfs_buf_find_insert(
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struct xfs_buftarg *btp,
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struct xfs_perag *pag,
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struct xfs_buf *new_bp)
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{
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/* No match found */
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if (!new_bp) {
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xfs_perag_put(pag);
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XFS_STATS_INC(btp->bt_mount, xb_miss_locked);
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return -ENOENT;
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}
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/* the buffer keeps the perag reference until it is freed */
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new_bp->b_pag = pag;
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rhashtable_insert_fast(&pag->pag_buf_hash, &new_bp->b_rhash_head,
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xfs_buf_hash_params);
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return 0;
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}
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/*
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* Look up a buffer in the buffer cache and return it referenced and locked
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* in @found_bp.
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*
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* If @new_bp is supplied and we have a lookup miss, insert @new_bp into the
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* cache.
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*
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* If XBF_TRYLOCK is set in @flags, only try to lock the buffer and return
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* -EAGAIN if we fail to lock it.
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*
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* Return values are:
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* -EFSCORRUPTED if have been supplied with an invalid address
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* -EAGAIN on trylock failure
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* -ENOENT if we fail to find a match and @new_bp was NULL
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* 0, with @found_bp:
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* - @new_bp if we inserted it into the cache
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* - the buffer we found and locked.
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*/
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static int
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xfs_buf_find(
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struct xfs_buftarg *btp,
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struct xfs_buf_map *map,
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int nmaps,
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xfs_buf_flags_t flags,
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struct xfs_buf *new_bp,
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struct xfs_buf **found_bp)
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{
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struct xfs_perag *pag;
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struct xfs_buf *bp;
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struct xfs_buf_map cmap = { .bm_bn = map[0].bm_bn };
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int error;
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int i;
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*found_bp = NULL;
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for (i = 0; i < nmaps; i++)
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cmap.bm_len += map[i].bm_len;
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error = xfs_buf_map_verify(btp, &cmap);
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if (error)
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return error;
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pag = xfs_perag_get(btp->bt_mount,
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xfs_daddr_to_agno(btp->bt_mount, cmap.bm_bn));
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spin_lock(&pag->pag_buf_lock);
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bp = xfs_buf_lookup(pag, &cmap);
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if (bp)
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goto found;
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error = xfs_buf_find_insert(btp, pag, new_bp);
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spin_unlock(&pag->pag_buf_lock);
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if (error)
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return error;
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*found_bp = new_bp;
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return 0;
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found:
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spin_unlock(&pag->pag_buf_lock);
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xfs_perag_put(pag);
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error = xfs_buf_find_lock(bp, flags);
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if (error)
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return error;
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trace_xfs_buf_find(bp, flags, _RET_IP_);
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XFS_STATS_INC(btp->bt_mount, xb_get_locked);
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*found_bp = bp;
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return 0;
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}
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/*
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* Assembles a buffer covering the specified range. The code is optimised for
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* cache hits, as metadata intensive workloads will see 3 orders of magnitude
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* more hits than misses.
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*/
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int
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xfs_buf_get_map(
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struct xfs_buftarg *target,
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struct xfs_buf_map *cmap,
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struct xfs_buf_map *map,
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int nmaps,
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xfs_buf_flags_t flags,
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struct xfs_buf **bpp)
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{
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struct xfs_buf *bp;
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struct xfs_buf *new_bp;
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struct xfs_buf *bp;
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int error;
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*bpp = NULL;
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error = xfs_buf_find(target, map, nmaps, flags, NULL, &bp);
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if (!error)
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goto found;
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if (error != -ENOENT)
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return error;
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if (flags & XBF_INCORE)
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return -ENOENT;
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error = _xfs_buf_alloc(target, map, nmaps, flags, &new_bp);
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error = _xfs_buf_alloc(btp, map, nmaps, flags, &new_bp);
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if (error)
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return error;
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goto out_drop_pag;
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/*
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* For buffers that fit entirely within a single page, first attempt to
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@ -709,18 +621,89 @@ xfs_buf_get_map(
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goto out_free_buf;
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}
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error = xfs_buf_find(target, map, nmaps, flags, new_bp, &bp);
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if (error)
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spin_lock(&pag->pag_buf_lock);
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bp = rhashtable_lookup(&pag->pag_buf_hash, cmap, xfs_buf_hash_params);
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if (bp) {
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atomic_inc(&bp->b_hold);
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spin_unlock(&pag->pag_buf_lock);
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error = xfs_buf_find_lock(bp, flags);
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if (error)
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xfs_buf_rele(bp);
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else
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*bpp = bp;
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goto out_free_buf;
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}
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if (bp != new_bp)
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xfs_buf_free(new_bp);
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/* The buffer keeps the perag reference until it is freed. */
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new_bp->b_pag = pag;
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rhashtable_insert_fast(&pag->pag_buf_hash, &new_bp->b_rhash_head,
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xfs_buf_hash_params);
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spin_unlock(&pag->pag_buf_lock);
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*bpp = new_bp;
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return 0;
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found:
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out_free_buf:
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xfs_buf_free(new_bp);
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out_drop_pag:
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xfs_perag_put(pag);
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return error;
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}
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/*
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* Assembles a buffer covering the specified range. The code is optimised for
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* cache hits, as metadata intensive workloads will see 3 orders of magnitude
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* more hits than misses.
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*/
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int
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xfs_buf_get_map(
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struct xfs_buftarg *btp,
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struct xfs_buf_map *map,
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int nmaps,
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xfs_buf_flags_t flags,
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struct xfs_buf **bpp)
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{
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struct xfs_perag *pag;
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struct xfs_buf *bp = NULL;
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struct xfs_buf_map cmap = { .bm_bn = map[0].bm_bn };
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int error;
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int i;
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for (i = 0; i < nmaps; i++)
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cmap.bm_len += map[i].bm_len;
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error = xfs_buf_map_verify(btp, &cmap);
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if (error)
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return error;
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pag = xfs_perag_get(btp->bt_mount,
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xfs_daddr_to_agno(btp->bt_mount, cmap.bm_bn));
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error = xfs_buf_lookup(pag, &cmap, flags, &bp);
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if (error && error != -ENOENT)
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goto out_put_perag;
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/* cache hits always outnumber misses by at least 10:1 */
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if (unlikely(!bp)) {
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XFS_STATS_INC(btp->bt_mount, xb_miss_locked);
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if (flags & XBF_INCORE)
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goto out_put_perag;
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/* xfs_buf_find_insert() consumes the perag reference. */
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error = xfs_buf_find_insert(btp, pag, &cmap, map, nmaps,
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flags, &bp);
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if (error)
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return error;
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} else {
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XFS_STATS_INC(btp->bt_mount, xb_get_locked);
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xfs_perag_put(pag);
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}
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/* We do not hold a perag reference anymore. */
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if (!bp->b_addr) {
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error = _xfs_buf_map_pages(bp, flags);
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if (unlikely(error)) {
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xfs_warn_ratelimited(target->bt_mount,
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xfs_warn_ratelimited(btp->bt_mount,
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"%s: failed to map %u pages", __func__,
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bp->b_page_count);
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xfs_buf_relse(bp);
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@ -735,12 +718,13 @@ found:
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if (!(flags & XBF_READ))
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xfs_buf_ioerror(bp, 0);
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XFS_STATS_INC(target->bt_mount, xb_get);
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XFS_STATS_INC(btp->bt_mount, xb_get);
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trace_xfs_buf_get(bp, flags, _RET_IP_);
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*bpp = bp;
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return 0;
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out_free_buf:
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xfs_buf_free(new_bp);
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out_put_perag:
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xfs_perag_put(pag);
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return error;
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}
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