1 files changed, 41 insertions, 34 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index c98805c35bab..2234e88cf674 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1534,30 +1534,30 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
 		reserve_bytes = round_up(write_bytes + sector_offset,
 				root->sectorsize);
 
-		if ((BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW |
-					      BTRFS_INODE_PREALLOC)) &&
-		    check_can_nocow(inode, pos, &write_bytes) > 0) {
-			/*
-			 * For nodata cow case, no need to reserve
-			 * data space.
-			 */
-			only_release_metadata = true;
-			/*
-			 * our prealloc extent may be smaller than
-			 * write_bytes, so scale down.
-			 */
-			num_pages = DIV_ROUND_UP(write_bytes + offset,
-						 PAGE_SIZE);
-			reserve_bytes = round_up(write_bytes + sector_offset,
-					root->sectorsize);
-			goto reserve_metadata;
-		}
-
 		ret = btrfs_check_data_free_space(inode, pos, write_bytes);
-		if (ret < 0)
-			break;
+		if (ret < 0) {
+			if ((BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW |
+						      BTRFS_INODE_PREALLOC)) &&
+			    check_can_nocow(inode, pos, &write_bytes) > 0) {
+				/*
+				 * For nodata cow case, no need to reserve
+				 * data space.
+				 */
+				only_release_metadata = true;
+				/*
+				 * our prealloc extent may be smaller than
+				 * write_bytes, so scale down.
+				 */
+				num_pages = DIV_ROUND_UP(write_bytes + offset,
+							 PAGE_SIZE);
+				reserve_bytes = round_up(write_bytes +
+							 sector_offset,
+							 root->sectorsize);
+			} else {
+				break;
+			}
+		}
 
-reserve_metadata:
 		ret = btrfs_delalloc_reserve_metadata(inode, reserve_bytes);
 		if (ret) {
 			if (!only_release_metadata)
@@ -1596,6 +1596,13 @@ again:
 
 		copied = btrfs_copy_from_user(pos, write_bytes, pages, i);
 
+		num_sectors = BTRFS_BYTES_TO_BLKS(root->fs_info,
+						reserve_bytes);
+		dirty_sectors = round_up(copied + sector_offset,
+					root->sectorsize);
+		dirty_sectors = BTRFS_BYTES_TO_BLKS(root->fs_info,
+						dirty_sectors);
+
 		/*
 		 * if we have trouble faulting in the pages, fall
 		 * back to one page at a time
@@ -1605,6 +1612,7 @@ again:
 
 		if (copied == 0) {
 			force_page_uptodate = true;
+			dirty_sectors = 0;
 			dirty_pages = 0;
 		} else {
 			force_page_uptodate = false;
@@ -1615,20 +1623,19 @@ again:
 		/*
 		 * If we had a short copy we need to release the excess delaloc
 		 * bytes we reserved.  We need to increment outstanding_extents
-		 * because btrfs_delalloc_release_space will decrement it, but
+		 * because btrfs_delalloc_release_space and
+		 * btrfs_delalloc_release_metadata will decrement it, but
 		 * we still have an outstanding extent for the chunk we actually
 		 * managed to copy.
 		 */
-		num_sectors = BTRFS_BYTES_TO_BLKS(root->fs_info,
-						reserve_bytes);
-		dirty_sectors = round_up(copied + sector_offset,
-					root->sectorsize);
-		dirty_sectors = BTRFS_BYTES_TO_BLKS(root->fs_info,
-						dirty_sectors);
-
 		if (num_sectors > dirty_sectors) {
-			release_bytes = (write_bytes - copied)
-				& ~((u64)root->sectorsize - 1);
+			/*
+			 * we round down because we don't want to count
+			 * any partial blocks actually sent through the
+			 * IO machines
+			 */
+			release_bytes = round_down(release_bytes - copied,
+				      root->sectorsize);
 			if (copied > 0) {
 				spin_lock(&BTRFS_I(inode)->lock);
 				BTRFS_I(inode)->outstanding_extents++;
@@ -2022,7 +2029,7 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
 	     BTRFS_I(inode)->last_trans
 	     <= root->fs_info->last_trans_committed)) {
 		/*
-		 * We'v had everything committed since the last time we were
+		 * We've had everything committed since the last time we were
 		 * modified so clear this flag in case it was set for whatever
 		 * reason, it's no longer relevant.
 		 */
@@ -2370,7 +2377,7 @@ static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
 
 	/* Check the aligned pages after the first unaligned page,
 	 * if offset != orig_start, which means the first unaligned page
-	 * including serveral following pages are already in holes,
+	 * including several following pages are already in holes,
 	 * the extra check can be skipped */
 	if (offset == orig_start) {
 		/* after truncate page, check hole again */