btrfs: refactor btrfs_check_can_nocow() into two variants

The function btrfs_check_can_nocow() now has two completely different
call patterns.

For nowait variant, callers don't need to do any cleanup.  While for
wait variant, callers need to release the lock if they can do nocow
write.

This is somehow confusing, and is already a problem for the exported
btrfs_check_can_nocow().

So this patch will separate the different patterns into different
functions.
For nowait variant, the function will be called check_nocow_nolock().
For wait variant, the function pair will be btrfs_check_nocow_lock()
btrfs_check_nocow_unlock().

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 3 insertions, 5 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 37c864e6b5bc..bd51365e53fb 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4534,10 +4534,8 @@ int btrfs_truncate_block(struct inode *inode, loff_t from, loff_t len,
 	ret = btrfs_check_data_free_space(inode, &data_reserved, block_start,
 					  blocksize);
 	if (ret < 0) {
-		if ((BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW |
-					      BTRFS_INODE_PREALLOC)) &&
-		    btrfs_check_can_nocow(BTRFS_I(inode), block_start,
-					  &write_bytes, false) > 0) {
+		if (btrfs_check_nocow_lock(BTRFS_I(inode), block_start,
+					   &write_bytes) > 0) {
 			/* For nocow case, no need to reserve data space */
 			only_release_metadata = true;
 		} else {
@@ -4638,7 +4636,7 @@ out_unlock:
 	put_page(page);
 out:
 	if (only_release_metadata)
-		btrfs_drew_write_unlock(&BTRFS_I(inode)->root->snapshot_lock);
+		btrfs_check_nocow_unlock(BTRFS_I(inode));
 	extent_changeset_free(data_reserved);
 	return ret;
 }