1 files changed, 96 insertions, 65 deletions

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index a0229c368e78..217e4f82a44a 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -198,20 +198,22 @@ xfs_buf_free_maps(
 	}
 }
 
-static struct xfs_buf *
+static int
 _xfs_buf_alloc(
 	struct xfs_buftarg	*target,
 	struct xfs_buf_map	*map,
 	int			nmaps,
-	xfs_buf_flags_t		flags)
+	xfs_buf_flags_t		flags,
+	struct xfs_buf		**bpp)
 {
 	struct xfs_buf		*bp;
 	int			error;
 	int			i;
 
+	*bpp = NULL;
 	bp = kmem_zone_zalloc(xfs_buf_zone, KM_NOFS);
 	if (unlikely(!bp))
-		return NULL;
+		return -ENOMEM;
 
 	/*
 	 * We don't want certain flags to appear in b_flags unless they are
@@ -239,7 +241,7 @@ _xfs_buf_alloc(
 	error = xfs_buf_get_maps(bp, nmaps);
 	if (error)  {
 		kmem_cache_free(xfs_buf_zone, bp);
-		return NULL;
+		return error;
 	}
 
 	bp->b_bn = map[0].bm_bn;
@@ -256,7 +258,8 @@ _xfs_buf_alloc(
 	XFS_STATS_INC(bp->b_mount, xb_create);
 	trace_xfs_buf_init(bp, _RET_IP_);
 
-	return bp;
+	*bpp = bp;
+	return 0;
 }
 
 /*
@@ -682,53 +685,39 @@ xfs_buf_incore(
  * cache hits, as metadata intensive workloads will see 3 orders of magnitude
  * more hits than misses.
  */
-struct xfs_buf *
+int
 xfs_buf_get_map(
 	struct xfs_buftarg	*target,
 	struct xfs_buf_map	*map,
 	int			nmaps,
-	xfs_buf_flags_t		flags)
+	xfs_buf_flags_t		flags,
+	struct xfs_buf		**bpp)
 {
 	struct xfs_buf		*bp;
 	struct xfs_buf		*new_bp;
 	int			error = 0;
 
+	*bpp = NULL;
 	error = xfs_buf_find(target, map, nmaps, flags, NULL, &bp);
-
-	switch (error) {
-	case 0:
-		/* cache hit */
+	if (!error)
 		goto found;
-	case -EAGAIN:
-		/* cache hit, trylock failure, caller handles failure */
-		ASSERT(flags & XBF_TRYLOCK);
-		return NULL;
-	case -ENOENT:
-		/* cache miss, go for insert */
-		break;
-	case -EFSCORRUPTED:
-	default:
-		/*
-		 * None of the higher layers understand failure types
-		 * yet, so return NULL to signal a fatal lookup error.
-		 */
-		return NULL;
-	}
+	if (error != -ENOENT)
+		return error;
 
-	new_bp = _xfs_buf_alloc(target, map, nmaps, flags);
-	if (unlikely(!new_bp))
-		return NULL;
+	error = _xfs_buf_alloc(target, map, nmaps, flags, &new_bp);
+	if (error)
+		return error;
 
 	error = xfs_buf_allocate_memory(new_bp, flags);
 	if (error) {
 		xfs_buf_free(new_bp);
-		return NULL;
+		return error;
 	}
 
 	error = xfs_buf_find(target, map, nmaps, flags, new_bp, &bp);
 	if (error) {
 		xfs_buf_free(new_bp);
-		return NULL;
+		return error;
 	}
 
 	if (bp != new_bp)
@@ -741,7 +730,7 @@ found:
 			xfs_warn(target->bt_mount,
 				"%s: failed to map pagesn", __func__);
 			xfs_buf_relse(bp);
-			return NULL;
+			return error;
 		}
 	}
 
@@ -754,7 +743,8 @@ found:
 
 	XFS_STATS_INC(target->bt_mount, xb_get);
 	trace_xfs_buf_get(bp, flags, _RET_IP_);
-	return bp;
+	*bpp = bp;
+	return 0;
 }
 
 STATIC int
@@ -806,46 +796,77 @@ xfs_buf_reverify(
 	return bp->b_error;
 }
 
-xfs_buf_t *
+int
 xfs_buf_read_map(
 	struct xfs_buftarg	*target,
 	struct xfs_buf_map	*map,
 	int			nmaps,
 	xfs_buf_flags_t		flags,
-	const struct xfs_buf_ops *ops)
+	struct xfs_buf		**bpp,
+	const struct xfs_buf_ops *ops,
+	xfs_failaddr_t		fa)
 {
 	struct xfs_buf		*bp;
+	int			error;
 
 	flags |= XBF_READ;
+	*bpp = NULL;
 
-	bp = xfs_buf_get_map(target, map, nmaps, flags);
-	if (!bp)
-		return NULL;
+	error = xfs_buf_get_map(target, map, nmaps, flags, &bp);
+	if (error)
+		return error;
 
 	trace_xfs_buf_read(bp, flags, _RET_IP_);
 
 	if (!(bp->b_flags & XBF_DONE)) {
+		/* Initiate the buffer read and wait. */
 		XFS_STATS_INC(target->bt_mount, xb_get_read);
 		bp->b_ops = ops;
-		_xfs_buf_read(bp, flags);
-		return bp;
+		error = _xfs_buf_read(bp, flags);
+
+		/* Readahead iodone already dropped the buffer, so exit. */
+		if (flags & XBF_ASYNC)
+			return 0;
+	} else {
+		/* Buffer already read; all we need to do is check it. */
+		error = xfs_buf_reverify(bp, ops);
+
+		/* Readahead already finished; drop the buffer and exit. */
+		if (flags & XBF_ASYNC) {
+			xfs_buf_relse(bp);
+			return 0;
+		}
+
+		/* We do not want read in the flags */
+		bp->b_flags &= ~XBF_READ;
+		ASSERT(bp->b_ops != NULL || ops == NULL);
 	}
 
-	xfs_buf_reverify(bp, ops);
+	/*
+	 * If we've had a read error, then the contents of the buffer are
+	 * invalid and should not be used. To ensure that a followup read tries
+	 * to pull the buffer from disk again, we clear the XBF_DONE flag and
+	 * mark the buffer stale. This ensures that anyone who has a current
+	 * reference to the buffer will interpret it's contents correctly and
+	 * future cache lookups will also treat it as an empty, uninitialised
+	 * buffer.
+	 */
+	if (error) {
+		if (!XFS_FORCED_SHUTDOWN(target->bt_mount))
+			xfs_buf_ioerror_alert(bp, fa);
 
-	if (flags & XBF_ASYNC) {
-		/*
-		 * Read ahead call which is already satisfied,
-		 * drop the buffer
-		 */
+		bp->b_flags &= ~XBF_DONE;
+		xfs_buf_stale(bp);
 		xfs_buf_relse(bp);
-		return NULL;
+
+		/* bad CRC means corrupted metadata */
+		if (error == -EFSBADCRC)
+			error = -EFSCORRUPTED;
+		return error;
 	}
 
-	/* We do not want read in the flags */
-	bp->b_flags &= ~XBF_READ;
-	ASSERT(bp->b_ops != NULL || ops == NULL);
-	return bp;
+	*bpp = bp;
+	return 0;
 }
 
 /*
@@ -859,11 +880,14 @@ xfs_buf_readahead_map(
 	int			nmaps,
 	const struct xfs_buf_ops *ops)
 {
+	struct xfs_buf		*bp;
+
 	if (bdi_read_congested(target->bt_bdev->bd_bdi))
 		return;
 
 	xfs_buf_read_map(target, map, nmaps,
-		     XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD, ops);
+		     XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD, &bp, ops,
+		     __this_address);
 }
 
 /*
@@ -880,12 +904,13 @@ xfs_buf_read_uncached(
 	const struct xfs_buf_ops *ops)
 {
 	struct xfs_buf		*bp;
+	int			error;
 
 	*bpp = NULL;
 
-	bp = xfs_buf_get_uncached(target, numblks, flags);
-	if (!bp)
-		return -ENOMEM;
+	error = xfs_buf_get_uncached(target, numblks, flags, &bp);
+	if (error)
+		return error;
 
 	/* set up the buffer for a read IO */
 	ASSERT(bp->b_map_count == 1);
@@ -896,7 +921,7 @@ xfs_buf_read_uncached(
 
 	xfs_buf_submit(bp);
 	if (bp->b_error) {
-		int	error = bp->b_error;
+		error = bp->b_error;
 		xfs_buf_relse(bp);
 		return error;
 	}
@@ -905,20 +930,23 @@ xfs_buf_read_uncached(
 	return 0;
 }
 
-xfs_buf_t *
+int
 xfs_buf_get_uncached(
 	struct xfs_buftarg	*target,
 	size_t			numblks,
-	int			flags)
+	int			flags,
+	struct xfs_buf		**bpp)
 {
 	unsigned long		page_count;
 	int			error, i;
 	struct xfs_buf		*bp;
 	DEFINE_SINGLE_BUF_MAP(map, XFS_BUF_DADDR_NULL, numblks);
 
+	*bpp = NULL;
+
 	/* flags might contain irrelevant bits, pass only what we care about */
-	bp = _xfs_buf_alloc(target, &map, 1, flags & XBF_NO_IOACCT);
-	if (unlikely(bp == NULL))
+	error = _xfs_buf_alloc(target, &map, 1, flags & XBF_NO_IOACCT, &bp);
+	if (error)
 		goto fail;
 
 	page_count = PAGE_ALIGN(numblks << BBSHIFT) >> PAGE_SHIFT;
@@ -928,8 +956,10 @@ xfs_buf_get_uncached(
 
 	for (i = 0; i < page_count; i++) {
 		bp->b_pages[i] = alloc_page(xb_to_gfp(flags));
-		if (!bp->b_pages[i])
+		if (!bp->b_pages[i]) {
+			error = -ENOMEM;
 			goto fail_free_mem;
+		}
 	}
 	bp->b_flags |= _XBF_PAGES;
 
@@ -941,7 +971,8 @@ xfs_buf_get_uncached(
 	}
 
 	trace_xfs_buf_get_uncached(bp, _RET_IP_);
-	return bp;
+	*bpp = bp;
+	return 0;
 
  fail_free_mem:
 	while (--i >= 0)
@@ -951,7 +982,7 @@ xfs_buf_get_uncached(
 	xfs_buf_free_maps(bp);
 	kmem_cache_free(xfs_buf_zone, bp);
  fail:
-	return NULL;
+	return error;
 }
 
 /*
@@ -1205,10 +1236,10 @@ __xfs_buf_ioerror(
 void
 xfs_buf_ioerror_alert(
 	struct xfs_buf		*bp,
-	const char		*func)
+	xfs_failaddr_t		func)
 {
 	xfs_alert(bp->b_mount,
-"metadata I/O error in \"%s\" at daddr 0x%llx len %d error %d",
+"metadata I/O error in \"%pS\" at daddr 0x%llx len %d error %d",
 			func, (uint64_t)XFS_BUF_ADDR(bp), bp->b_length,
 			-bp->b_error);
 }