diff options
Diffstat (limited to 'fs/xfs')
| -rw-r--r-- | fs/xfs/linux-2.6/xfs_buf.c | 164 | ||||
| -rw-r--r-- | fs/xfs/linux-2.6/xfs_buf.h | 8 |
2 files changed, 150 insertions, 22 deletions
diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c index 0a00d7a2fc2..92f1f2acc6a 100644 --- a/fs/xfs/linux-2.6/xfs_buf.c +++ b/fs/xfs/linux-2.6/xfs_buf.c @@ -163,8 +163,79 @@ test_page_region( } /* - * Internal xfs_buf_t object manipulation + * xfs_buf_lru_add - add a buffer to the LRU. + * + * The LRU takes a new reference to the buffer so that it will only be freed + * once the shrinker takes the buffer off the LRU. */ +STATIC void +xfs_buf_lru_add( + struct xfs_buf *bp) +{ + struct xfs_buftarg *btp = bp->b_target; + + spin_lock(&btp->bt_lru_lock); + if (list_empty(&bp->b_lru)) { + atomic_inc(&bp->b_hold); + list_add_tail(&bp->b_lru, &btp->bt_lru); + btp->bt_lru_nr++; + } + spin_unlock(&btp->bt_lru_lock); +} + +/* + * xfs_buf_lru_del - remove a buffer from the LRU + * + * The unlocked check is safe here because it only occurs when there are not + * b_lru_ref counts left on the inode under the pag->pag_buf_lock. it is there + * to optimise the shrinker removing the buffer from the LRU and calling + * xfs_buf_free(). i.e. it removes an unneccessary round trip on the + * bt_lru_lock. + */ +STATIC void +xfs_buf_lru_del( + struct xfs_buf *bp) +{ + struct xfs_buftarg *btp = bp->b_target; + + if (list_empty(&bp->b_lru)) + return; + + spin_lock(&btp->bt_lru_lock); + if (!list_empty(&bp->b_lru)) { + list_del_init(&bp->b_lru); + btp->bt_lru_nr--; + } + spin_unlock(&btp->bt_lru_lock); +} + +/* + * When we mark a buffer stale, we remove the buffer from the LRU and clear the + * b_lru_ref count so that the buffer is freed immediately when the buffer + * reference count falls to zero. If the buffer is already on the LRU, we need + * to remove the reference that LRU holds on the buffer. + * + * This prevents build-up of stale buffers on the LRU. + */ +void +xfs_buf_stale( + struct xfs_buf *bp) +{ + bp->b_flags |= XBF_STALE; + atomic_set(&(bp)->b_lru_ref, 0); + if (!list_empty(&bp->b_lru)) { + struct xfs_buftarg *btp = bp->b_target; + + spin_lock(&btp->bt_lru_lock); + if (!list_empty(&bp->b_lru)) { + list_del_init(&bp->b_lru); + btp->bt_lru_nr--; + atomic_dec(&bp->b_hold); + } + spin_unlock(&btp->bt_lru_lock); + } + ASSERT(atomic_read(&bp->b_hold) >= 1); +} STATIC void _xfs_buf_initialize( @@ -181,7 +252,9 @@ _xfs_buf_initialize( memset(bp, 0, sizeof(xfs_buf_t)); atomic_set(&bp->b_hold, 1); + atomic_set(&bp->b_lru_ref, 1); init_completion(&bp->b_iowait); + INIT_LIST_HEAD(&bp->b_lru); INIT_LIST_HEAD(&bp->b_list); RB_CLEAR_NODE(&bp->b_rbnode); sema_init(&bp->b_sema, 0); /* held, no waiters */ @@ -257,6 +330,8 @@ xfs_buf_free( { trace_xfs_buf_free(bp, _RET_IP_); + ASSERT(list_empty(&bp->b_lru)); + if (bp->b_flags & (_XBF_PAGE_CACHE|_XBF_PAGES)) { uint i; @@ -822,6 +897,7 @@ xfs_buf_rele( if (!pag) { ASSERT(!bp->b_relse); + ASSERT(list_empty(&bp->b_lru)); ASSERT(RB_EMPTY_NODE(&bp->b_rbnode)); if (atomic_dec_and_test(&bp->b_hold)) xfs_buf_free(bp); @@ -829,13 +905,19 @@ xfs_buf_rele( } ASSERT(!RB_EMPTY_NODE(&bp->b_rbnode)); + ASSERT(atomic_read(&bp->b_hold) > 0); if (atomic_dec_and_lock(&bp->b_hold, &pag->pag_buf_lock)) { if (bp->b_relse) { atomic_inc(&bp->b_hold); spin_unlock(&pag->pag_buf_lock); bp->b_relse(bp); + } else if (!(bp->b_flags & XBF_STALE) && + atomic_read(&bp->b_lru_ref)) { + xfs_buf_lru_add(bp); + spin_unlock(&pag->pag_buf_lock); } else { + xfs_buf_lru_del(bp); ASSERT(!(bp->b_flags & (XBF_DELWRI|_XBF_DELWRI_Q))); rb_erase(&bp->b_rbnode, &pag->pag_buf_tree); spin_unlock(&pag->pag_buf_lock); @@ -1432,27 +1514,35 @@ xfs_buf_iomove( */ /* - * Wait for any bufs with callbacks that have been submitted but - * have not yet returned... walk the hash list for the target. + * Wait for any bufs with callbacks that have been submitted but have not yet + * returned. These buffers will have an elevated hold count, so wait on those + * while freeing all the buffers only held by the LRU. */ void xfs_wait_buftarg( struct xfs_buftarg *btp) { - struct xfs_perag *pag; - uint i; + struct xfs_buf *bp; - for (i = 0; i < btp->bt_mount->m_sb.sb_agcount; i++) { - pag = xfs_perag_get(btp->bt_mount, i); - spin_lock(&pag->pag_buf_lock); - while (rb_first(&pag->pag_buf_tree)) { - spin_unlock(&pag->pag_buf_lock); +restart: + spin_lock(&btp->bt_lru_lock); + while (!list_empty(&btp->bt_lru)) { + bp = list_first_entry(&btp->bt_lru, struct xfs_buf, b_lru); + if (atomic_read(&bp->b_hold) > 1) { + spin_unlock(&btp->bt_lru_lock); delay(100); - spin_lock(&pag->pag_buf_lock); + goto restart; } - spin_unlock(&pag->pag_buf_lock); - xfs_perag_put(pag); + /* + * clear the LRU reference count so the bufer doesn't get + * ignored in xfs_buf_rele(). + */ + atomic_set(&bp->b_lru_ref, 0); + spin_unlock(&btp->bt_lru_lock); + xfs_buf_rele(bp); + spin_lock(&btp->bt_lru_lock); } + spin_unlock(&btp->bt_lru_lock); } int @@ -1463,15 +1553,45 @@ xfs_buftarg_shrink( { struct xfs_buftarg *btp = container_of(shrink, struct xfs_buftarg, bt_shrinker); - if (nr_to_scan) { - if (test_bit(XBT_FORCE_SLEEP, &btp->bt_flags)) - return -1; - if (list_empty(&btp->bt_delwrite_queue)) - return -1; - set_bit(XBT_FORCE_FLUSH, &btp->bt_flags); - wake_up_process(btp->bt_task); + struct xfs_buf *bp; + LIST_HEAD(dispose); + + if (!nr_to_scan) + return btp->bt_lru_nr; + + spin_lock(&btp->bt_lru_lock); + while (!list_empty(&btp->bt_lru)) { + if (nr_to_scan-- <= 0) + break; + + bp = list_first_entry(&btp->bt_lru, struct xfs_buf, b_lru); + + /* + * Decrement the b_lru_ref count unless the value is already + * zero. If the value is already zero, we need to reclaim the + * buffer, otherwise it gets another trip through the LRU. + */ + if (!atomic_add_unless(&bp->b_lru_ref, -1, 0)) { + list_move_tail(&bp->b_lru, &btp->bt_lru); + continue; + } + + /* + * remove the buffer from the LRU now to avoid needing another + * lock round trip inside xfs_buf_rele(). + */ + list_move(&bp->b_lru, &dispose); + btp->bt_lru_nr--; } - return list_empty(&btp->bt_delwrite_queue) ? -1 : 1; + spin_unlock(&btp->bt_lru_lock); + + while (!list_empty(&dispose)) { + bp = list_first_entry(&dispose, struct xfs_buf, b_lru); + list_del_init(&bp->b_lru); + xfs_buf_rele(bp); + } + + return btp->bt_lru_nr; } void @@ -1606,6 +1726,8 @@ xfs_alloc_buftarg( btp->bt_mount = mp; btp->bt_dev = bdev->bd_dev; btp->bt_bdev = bdev; + INIT_LIST_HEAD(&btp->bt_lru); + spin_lock_init(&btp->bt_lru_lock); if (xfs_setsize_buftarg_early(btp, bdev)) goto error; if (xfs_mapping_buftarg(btp, bdev)) diff --git a/fs/xfs/linux-2.6/xfs_buf.h b/fs/xfs/linux-2.6/xfs_buf.h index 9344103e77d..4601eabd0da 100644 --- a/fs/xfs/linux-2.6/xfs_buf.h +++ b/fs/xfs/linux-2.6/xfs_buf.h @@ -134,6 +134,9 @@ typedef struct xfs_buftarg { /* LRU control structures */ struct shrinker bt_shrinker; + struct list_head bt_lru; + spinlock_t bt_lru_lock; + unsigned int bt_lru_nr; } xfs_buftarg_t; /* @@ -166,9 +169,11 @@ typedef struct xfs_buf { xfs_off_t b_file_offset; /* offset in file */ size_t b_buffer_length;/* size of buffer in bytes */ atomic_t b_hold; /* reference count */ + atomic_t b_lru_ref; /* lru reclaim ref count */ xfs_buf_flags_t b_flags; /* status flags */ struct semaphore b_sema; /* semaphore for lockables */ + struct list_head b_lru; /* lru list */ wait_queue_head_t b_waiters; /* unpin waiters */ struct list_head b_list; struct xfs_perag *b_pag; /* contains rbtree root */ @@ -266,7 +271,8 @@ extern void xfs_buf_terminate(void); #define XFS_BUF_ZEROFLAGS(bp) ((bp)->b_flags &= \ ~(XBF_READ|XBF_WRITE|XBF_ASYNC|XBF_DELWRI|XBF_ORDERED)) -#define XFS_BUF_STALE(bp) ((bp)->b_flags |= XBF_STALE) +void xfs_buf_stale(struct xfs_buf *bp); +#define XFS_BUF_STALE(bp) xfs_buf_stale(bp); #define XFS_BUF_UNSTALE(bp) ((bp)->b_flags &= ~XBF_STALE) #define XFS_BUF_ISSTALE(bp) ((bp)->b_flags & XBF_STALE) #define XFS_BUF_SUPER_STALE(bp) do { \ |