#include "xfs_error.h"
#include "xfs_ag.h"
-static struct kmem_cache *xfs_buf_cache;
+struct kmem_cache *xfs_buf_cache;
/*
* Locking orders
bp->b_flags &= ~_XBF_PAGES;
}
+static void
+xfs_buf_free_callback(
+ struct callback_head *cb)
+{
+ struct xfs_buf *bp = container_of(cb, struct xfs_buf, b_rcu);
+
+ xfs_buf_free_maps(bp);
+ kmem_cache_free(xfs_buf_cache, bp);
+}
+
static void
xfs_buf_free(
struct xfs_buf *bp)
else if (bp->b_flags & _XBF_KMEM)
kmem_free(bp->b_addr);
- xfs_buf_free_maps(bp);
- kmem_cache_free(xfs_buf_cache, bp);
+ call_rcu(&bp->b_rcu, xfs_buf_free_callback);
}
static int
rhashtable_destroy(&pag->pag_buf_hash);
}
-/*
- * Look up a buffer in the buffer cache and return it referenced and locked
- * in @found_bp.
- *
- * If @new_bp is supplied and we have a lookup miss, insert @new_bp into the
- * cache.
- *
- * If XBF_TRYLOCK is set in @flags, only try to lock the buffer and return
- * -EAGAIN if we fail to lock it.
- *
- * Return values are:
- * -EFSCORRUPTED if have been supplied with an invalid address
- * -EAGAIN on trylock failure
- * -ENOENT if we fail to find a match and @new_bp was NULL
- * 0, with @found_bp:
- * - @new_bp if we inserted it into the cache
- * - the buffer we found and locked.
- */
static int
-xfs_buf_find(
+xfs_buf_map_verify(
struct xfs_buftarg *btp,
- struct xfs_buf_map *map,
- int nmaps,
- xfs_buf_flags_t flags,
- struct xfs_buf *new_bp,
- struct xfs_buf **found_bp)
+ struct xfs_buf_map *map)
{
- struct xfs_perag *pag;
- struct xfs_buf *bp;
- struct xfs_buf_map cmap = { .bm_bn = map[0].bm_bn };
xfs_daddr_t eofs;
- int i;
-
- *found_bp = NULL;
-
- for (i = 0; i < nmaps; i++)
- cmap.bm_len += map[i].bm_len;
/* Check for IOs smaller than the sector size / not sector aligned */
- ASSERT(!(BBTOB(cmap.bm_len) < btp->bt_meta_sectorsize));
- ASSERT(!(BBTOB(cmap.bm_bn) & (xfs_off_t)btp->bt_meta_sectormask));
+ ASSERT(!(BBTOB(map->bm_len) < btp->bt_meta_sectorsize));
+ ASSERT(!(BBTOB(map->bm_bn) & (xfs_off_t)btp->bt_meta_sectormask));
/*
* Corrupted block numbers can get through to here, unfortunately, so we
* have to check that the buffer falls within the filesystem bounds.
*/
eofs = XFS_FSB_TO_BB(btp->bt_mount, btp->bt_mount->m_sb.sb_dblocks);
- if (cmap.bm_bn < 0 || cmap.bm_bn >= eofs) {
+ if (map->bm_bn < 0 || map->bm_bn >= eofs) {
xfs_alert(btp->bt_mount,
"%s: daddr 0x%llx out of range, EOFS 0x%llx",
- __func__, cmap.bm_bn, eofs);
+ __func__, map->bm_bn, eofs);
WARN_ON(1);
return -EFSCORRUPTED;
}
-
- pag = xfs_perag_get(btp->bt_mount,
- xfs_daddr_to_agno(btp->bt_mount, cmap.bm_bn));
-
- spin_lock(&pag->pag_buf_lock);
- bp = rhashtable_lookup_fast(&pag->pag_buf_hash, &cmap,
- xfs_buf_hash_params);
- if (bp) {
- atomic_inc(&bp->b_hold);
- goto found;
- }
-
- /* No match found */
- if (!new_bp) {
- XFS_STATS_INC(btp->bt_mount, xb_miss_locked);
- spin_unlock(&pag->pag_buf_lock);
- xfs_perag_put(pag);
- return -ENOENT;
- }
-
- /* the buffer keeps the perag reference until it is freed */
- new_bp->b_pag = pag;
- rhashtable_insert_fast(&pag->pag_buf_hash, &new_bp->b_rhash_head,
- xfs_buf_hash_params);
- spin_unlock(&pag->pag_buf_lock);
- *found_bp = new_bp;
return 0;
+}
-found:
- spin_unlock(&pag->pag_buf_lock);
- xfs_perag_put(pag);
-
- if (!xfs_buf_trylock(bp)) {
- if (flags & XBF_TRYLOCK) {
- xfs_buf_rele(bp);
- XFS_STATS_INC(btp->bt_mount, xb_busy_locked);
+static int
+xfs_buf_find_lock(
+ struct xfs_buf *bp,
+ xfs_buf_flags_t flags)
+{
+ if (flags & XBF_TRYLOCK) {
+ if (!xfs_buf_trylock(bp)) {
+ XFS_STATS_INC(bp->b_mount, xb_busy_locked);
return -EAGAIN;
}
+ } else {
xfs_buf_lock(bp);
- XFS_STATS_INC(btp->bt_mount, xb_get_locked_waited);
+ XFS_STATS_INC(bp->b_mount, xb_get_locked_waited);
}
/*
bp->b_flags &= _XBF_KMEM | _XBF_PAGES;
bp->b_ops = NULL;
}
-
- trace_xfs_buf_find(bp, flags, _RET_IP_);
- XFS_STATS_INC(btp->bt_mount, xb_get_locked);
- *found_bp = bp;
return 0;
}
-struct xfs_buf *
-xfs_buf_incore(
- struct xfs_buftarg *target,
- xfs_daddr_t blkno,
- size_t numblks,
- xfs_buf_flags_t flags)
+static inline int
+xfs_buf_lookup(
+ struct xfs_perag *pag,
+ struct xfs_buf_map *map,
+ xfs_buf_flags_t flags,
+ struct xfs_buf **bpp)
{
- struct xfs_buf *bp;
+ struct xfs_buf *bp;
int error;
- DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
- error = xfs_buf_find(target, &map, 1, flags, NULL, &bp);
- if (error)
- return NULL;
- return bp;
+ rcu_read_lock();
+ bp = rhashtable_lookup(&pag->pag_buf_hash, map, xfs_buf_hash_params);
+ if (!bp || !atomic_inc_not_zero(&bp->b_hold)) {
+ rcu_read_unlock();
+ return -ENOENT;
+ }
+ rcu_read_unlock();
+
+ error = xfs_buf_find_lock(bp, flags);
+ if (error) {
+ xfs_buf_rele(bp);
+ return error;
+ }
+
+ trace_xfs_buf_find(bp, flags, _RET_IP_);
+ *bpp = bp;
+ return 0;
}
/*
- * Assembles a buffer covering the specified range. The code is optimised for
- * cache hits, as metadata intensive workloads will see 3 orders of magnitude
- * more hits than misses.
+ * Insert the new_bp into the hash table. This consumes the perag reference
+ * taken for the lookup regardless of the result of the insert.
*/
-int
-xfs_buf_get_map(
- struct xfs_buftarg *target,
+static int
+xfs_buf_find_insert(
+ struct xfs_buftarg *btp,
+ struct xfs_perag *pag,
+ struct xfs_buf_map *cmap,
struct xfs_buf_map *map,
int nmaps,
xfs_buf_flags_t flags,
struct xfs_buf **bpp)
{
- struct xfs_buf *bp;
struct xfs_buf *new_bp;
+ struct xfs_buf *bp;
int error;
- *bpp = NULL;
- error = xfs_buf_find(target, map, nmaps, flags, NULL, &bp);
- if (!error)
- goto found;
- if (error != -ENOENT)
- return error;
-
- error = _xfs_buf_alloc(target, map, nmaps, flags, &new_bp);
+ error = _xfs_buf_alloc(btp, map, nmaps, flags, &new_bp);
if (error)
- return error;
+ goto out_drop_pag;
/*
* For buffers that fit entirely within a single page, first attempt to
goto out_free_buf;
}
- error = xfs_buf_find(target, map, nmaps, flags, new_bp, &bp);
- if (error)
+ spin_lock(&pag->pag_buf_lock);
+ bp = rhashtable_lookup_get_insert_fast(&pag->pag_buf_hash,
+ &new_bp->b_rhash_head, xfs_buf_hash_params);
+ if (IS_ERR(bp)) {
+ error = PTR_ERR(bp);
+ spin_unlock(&pag->pag_buf_lock);
goto out_free_buf;
+ }
+ if (bp) {
+ /* found an existing buffer */
+ atomic_inc(&bp->b_hold);
+ spin_unlock(&pag->pag_buf_lock);
+ error = xfs_buf_find_lock(bp, flags);
+ if (error)
+ xfs_buf_rele(bp);
+ else
+ *bpp = bp;
+ goto out_free_buf;
+ }
+
+ /* The new buffer keeps the perag reference until it is freed. */
+ new_bp->b_pag = pag;
+ spin_unlock(&pag->pag_buf_lock);
+ *bpp = new_bp;
+ return 0;
- if (bp != new_bp)
- xfs_buf_free(new_bp);
+out_free_buf:
+ xfs_buf_free(new_bp);
+out_drop_pag:
+ xfs_perag_put(pag);
+ return error;
+}
-found:
+/*
+ * Assembles a buffer covering the specified range. The code is optimised for
+ * cache hits, as metadata intensive workloads will see 3 orders of magnitude
+ * more hits than misses.
+ */
+int
+xfs_buf_get_map(
+ struct xfs_buftarg *btp,
+ struct xfs_buf_map *map,
+ int nmaps,
+ xfs_buf_flags_t flags,
+ struct xfs_buf **bpp)
+{
+ struct xfs_perag *pag;
+ struct xfs_buf *bp = NULL;
+ struct xfs_buf_map cmap = { .bm_bn = map[0].bm_bn };
+ int error;
+ int i;
+
+ for (i = 0; i < nmaps; i++)
+ cmap.bm_len += map[i].bm_len;
+
+ error = xfs_buf_map_verify(btp, &cmap);
+ if (error)
+ return error;
+
+ pag = xfs_perag_get(btp->bt_mount,
+ xfs_daddr_to_agno(btp->bt_mount, cmap.bm_bn));
+
+ error = xfs_buf_lookup(pag, &cmap, flags, &bp);
+ if (error && error != -ENOENT)
+ goto out_put_perag;
+
+ /* cache hits always outnumber misses by at least 10:1 */
+ if (unlikely(!bp)) {
+ XFS_STATS_INC(btp->bt_mount, xb_miss_locked);
+
+ if (flags & XBF_INCORE)
+ goto out_put_perag;
+
+ /* xfs_buf_find_insert() consumes the perag reference. */
+ error = xfs_buf_find_insert(btp, pag, &cmap, map, nmaps,
+ flags, &bp);
+ if (error)
+ return error;
+ } else {
+ XFS_STATS_INC(btp->bt_mount, xb_get_locked);
+ xfs_perag_put(pag);
+ }
+
+ /* We do not hold a perag reference anymore. */
if (!bp->b_addr) {
error = _xfs_buf_map_pages(bp, flags);
if (unlikely(error)) {
- xfs_warn_ratelimited(target->bt_mount,
+ xfs_warn_ratelimited(btp->bt_mount,
"%s: failed to map %u pages", __func__,
bp->b_page_count);
xfs_buf_relse(bp);
if (!(flags & XBF_READ))
xfs_buf_ioerror(bp, 0);
- XFS_STATS_INC(target->bt_mount, xb_get);
+ XFS_STATS_INC(btp->bt_mount, xb_get);
trace_xfs_buf_get(bp, flags, _RET_IP_);
*bpp = bp;
return 0;
-out_free_buf:
- xfs_buf_free(new_bp);
+
+out_put_perag:
+ xfs_perag_put(pag);
return error;
}
int map,
int *buf_offset,
int *count,
- int op)
+ blk_opf_t op)
{
int page_index;
unsigned int total_nr_pages = bp->b_page_count;
struct xfs_buf *bp)
{
struct blk_plug plug;
- int op;
+ blk_opf_t op;
int offset;
int size;
int i;
return error;
}
-int __init
-xfs_buf_init(void)
-{
- xfs_buf_cache = kmem_cache_create("xfs_buf", sizeof(struct xfs_buf), 0,
- SLAB_HWCACHE_ALIGN |
- SLAB_RECLAIM_ACCOUNT |
- SLAB_MEM_SPREAD,
- NULL);
- if (!xfs_buf_cache)
- goto out;
-
- return 0;
-
- out:
- return -ENOMEM;
-}
-
-void
-xfs_buf_terminate(void)
-{
- kmem_cache_destroy(xfs_buf_cache);
-}
-
void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
{
/*
projects / linux-2.6-microblaze.git / blobdiff