Btrfs: fix race between block group relocation and nocow writes

[deliverable/linux.git] / fs / btrfs / inode.c

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 45d0dafbbf4061cac324efb141254e5072aa822b..ee9be4199e7ca639742332b2362f252c7c3a368c 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1382,6 +1382,9 @@ next_slot:
                         */
                        if (csum_exist_in_range(root, disk_bytenr, num_bytes))
                                goto out_check;
+                       if (!btrfs_inc_nocow_writers(root->fs_info,
+                                                    disk_bytenr))
+                               goto out_check;
                        nocow = 1;
                } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
                        extent_end = found_key.offset +
@@ -1396,6 +1399,9 @@ out_check:
                        path->slots[0]++;
                        if (!nolock && nocow)
                                btrfs_end_write_no_snapshoting(root);
+                       if (nocow)
+                               btrfs_dec_nocow_writers(root->fs_info,
+                                                       disk_bytenr);
                        goto next_slot;
                }
                if (!nocow) {
@@ -1416,6 +1422,9 @@ out_check:
                        if (ret) {
                                if (!nolock && nocow)
                                        btrfs_end_write_no_snapshoting(root);
+                               if (nocow)
+                                       btrfs_dec_nocow_writers(root->fs_info,
+                                                               disk_bytenr);
                                goto error;
                        }
                        cow_start = (u64)-1;
@@ -1458,6 +1467,8 @@ out_check:
 
                ret = btrfs_add_ordered_extent(inode, cur_offset, disk_bytenr,
                                               num_bytes, num_bytes, type);
+               if (nocow)
+                       btrfs_dec_nocow_writers(root->fs_info, disk_bytenr);
                BUG_ON(ret); /* -ENOMEM */
 
                if (root->root_key.objectid ==
@@ -7657,7 +7668,8 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock,
                block_start = em->block_start + (start - em->start);
 
                if (can_nocow_extent(inode, start, &len, &orig_start,
-                                    &orig_block_len, &ram_bytes) == 1) {
+                                    &orig_block_len, &ram_bytes) == 1 &&
+                   btrfs_inc_nocow_writers(root->fs_info, block_start)) {
 
                        /*
                         * Create the ordered extent before the extent map. This
@@ -7672,6 +7684,7 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock,
                         */
                        ret = btrfs_add_ordered_extent_dio(inode, start,
                                           block_start, len, len, type);
+                       btrfs_dec_nocow_writers(root->fs_info, block_start);
                        if (ret) {
                                free_extent_map(em);
                                goto unlock_err;