Merge tag 'xfs-5.20-merge-6' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux

Pull xfs updates from Darrick Wong:
 "The biggest changes for this release are the log scalability
  improvements, lockless lookups for the buffer cache, and making the
  attr fork a permanent part of the incore inode in preparation for
  directory parent pointers.

  There's also a bunch of bug fixes that have accumulated since -rc5. I
  might send you a second pull request with some more bug fixes that I'm
  still working on.

  Once the merge window ends, I will hand maintainership back to Dave
  Chinner until the 6.1-rc1 release so that I can conduct the design
  review for the online fsck feature, and try to get it merged.

  Summary:

   - Improve scalability of the XFS log by removing spinlocks and global
     synchronization points.

   - Add security labels to whiteout inodes to match the other
     filesystems.

   - Clean up per-ag pointer passing to simplify call sites.

   - Reduce verifier overhead by precalculating more AG geometry.

   - Implement fast-path lockless lookups in the buffer cache to reduce
     spinlock hammering.

   - Make attr forks a permanent part of the inode structure to fix a
     UAF bug and because most files these days tend to have security
     labels and soon will have parent pointers too.

   - Clean up XFS_IFORK_Q usage and give it a better name.

   - Fix more UAF bugs in the xattr code.

   - SOB my tags.

   - Fix some typos in the timestamp range documentation.

   - Fix a few more memory leaks.

   - Code cleanups and typo fixes.

   - Fix an unlocked inode fork pointer access in getbmap"

* tag 'xfs-5.20-merge-6' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: (61 commits)
  xfs: delete extra space and tab in blank line
  xfs: fix NULL pointer dereference in xfs_getbmap()
  xfs: Fix typo 'the the' in comment
  xfs: Fix comment typo
  xfs: don't leak memory when attr fork loading fails
  xfs: fix for variable set but not used warning
  xfs: xfs_buf cache destroy isn't RCU safe
  xfs: delete unnecessary NULL checks
  xfs: fix comment for start time value of inode with bigtime enabled
  xfs: fix use-after-free in xattr node block inactivation
  xfs: lockless buffer lookup
  xfs: remove a superflous hash lookup when inserting new buffers
  xfs: reduce the number of atomic when locking a buffer after lookup
  xfs: merge xfs_buf_find() and xfs_buf_get_map()
  xfs: break up xfs_buf_find() into individual pieces
  xfs: add in-memory iunlink log item
  xfs: add log item precommit operation
  xfs: combine iunlink inode update functions
  xfs: clean up xfs_iunlink_update_inode()
  xfs: double link the unlinked inode list
  ...

1 files changed, 149 insertions, 139 deletions

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 5e8f40d8c052..584afe076923 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -21,7 +21,7 @@
 #include "xfs_error.h"
 #include "xfs_ag.h"
 
-static struct kmem_cache *xfs_buf_cache;
+struct kmem_cache *xfs_buf_cache;
 
 /*
  * Locking orders
@@ -295,6 +295,16 @@ xfs_buf_free_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)
 {
@@ -307,8 +317,7 @@ xfs_buf_free(
 	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
@@ -503,100 +512,45 @@ xfs_buf_hash_destroy(
 	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);
 	}
 
 	/*
@@ -609,57 +563,59 @@ found:
 		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
@@ -674,18 +630,94 @@ xfs_buf_get_map(
 			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);
@@ -700,12 +732,13 @@ found:
 	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;
 }
 
@@ -2275,29 +2308,6 @@ xfs_buf_delwri_pushbuf(
 	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)
 {
 	/*