btrfs: refactor btrfs_drop_extents() to make it easier to extend

There are many arguments for __btrfs_drop_extents() and its wrapper
btrfs_drop_extents(), which makes it hard to add more arguments to it and
requires changing every caller. I have added a couple myself back in 2014
commit 1acae57b161e ("Btrfs: faster file extent item replace operations")
and therefore know firsthand that it is a bit cumbersome to add additional
arguments to these functions.

Since I will need to add more arguments in a subsequent bug fix, this
change is preparatory work and adds a data structure that holds all the
arguments, for both input and output, that are passed to this function,
with some comments in the structure's definition mentioning what each
field is and how it relates to other fields.

Callers of this function need only to zero out the content of the
structure and setup only the fields they need. This also removes the
need to have both __btrfs_drop_extents() and btrfs_drop_extents(), so
now we have a single function named btrfs_drop_extents() that takes a
pointer to this new data structure (struct btrfs_drop_extents_args).

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 20 insertions, 8 deletions

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index b1f97be57bb3..89ff063cae24 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -576,6 +576,7 @@ static noinline int replay_one_extent(struct btrfs_trans_handle *trans,
 				      struct extent_buffer *eb, int slot,
 				      struct btrfs_key *key)
 {
+	struct btrfs_drop_extents_args drop_args = { 0 };
 	struct btrfs_fs_info *fs_info = root->fs_info;
 	int found_type;
 	u64 extent_end;
@@ -653,7 +654,10 @@ static noinline int replay_one_extent(struct btrfs_trans_handle *trans,
 	btrfs_release_path(path);
 
 	/* drop any overlapping extents */
-	ret = btrfs_drop_extents(trans, root, inode, start, extent_end, 1);
+	drop_args.start = start;
+	drop_args.end = extent_end;
+	drop_args.drop_cache = true;
+	ret = btrfs_drop_extents(trans, root, BTRFS_I(inode), &drop_args);
 	if (ret)
 		goto out;
 
@@ -2576,6 +2580,7 @@ static int replay_one_buffer(struct btrfs_root *log, struct extent_buffer *eb,
 			 * those prealloc extents just after replaying them.
 			 */
 			if (S_ISREG(mode)) {
+				struct btrfs_drop_extents_args drop_args = { 0 };
 				struct inode *inode;
 				u64 from;
 
@@ -2586,8 +2591,12 @@ static int replay_one_buffer(struct btrfs_root *log, struct extent_buffer *eb,
 				}
 				from = ALIGN(i_size_read(inode),
 					     root->fs_info->sectorsize);
-				ret = btrfs_drop_extents(wc->trans, root, inode,
-							 from, (u64)-1, 1);
+				drop_args.start = from;
+				drop_args.end = (u64)-1;
+				drop_args.drop_cache = true;
+				ret = btrfs_drop_extents(wc->trans, root,
+							 BTRFS_I(inode),
+							 &drop_args);
 				if (!ret) {
 					/* Update the inode's nbytes. */
 					ret = btrfs_update_inode(wc->trans,
@@ -4185,6 +4194,7 @@ static int log_one_extent(struct btrfs_trans_handle *trans,
 			  struct btrfs_path *path,
 			  struct btrfs_log_ctx *ctx)
 {
+	struct btrfs_drop_extents_args drop_args = { 0 };
 	struct btrfs_root *log = root->log_root;
 	struct btrfs_file_extent_item *fi;
 	struct extent_buffer *leaf;
@@ -4193,19 +4203,21 @@ static int log_one_extent(struct btrfs_trans_handle *trans,
 	u64 extent_offset = em->start - em->orig_start;
 	u64 block_len;
 	int ret;
-	int extent_inserted = 0;
 
 	ret = log_extent_csums(trans, inode, log, em, ctx);
 	if (ret)
 		return ret;
 
-	ret = __btrfs_drop_extents(trans, log, inode, path, em->start,
-				   em->start + em->len, NULL, 0, 1,
-				   sizeof(*fi), &extent_inserted);
+	drop_args.path = path;
+	drop_args.start = em->start;
+	drop_args.end = em->start + em->len;
+	drop_args.replace_extent = true;
+	drop_args.extent_item_size = sizeof(*fi);
+	ret = btrfs_drop_extents(trans, log, inode, &drop_args);
 	if (ret)
 		return ret;
 
-	if (!extent_inserted) {
+	if (!drop_args.extent_inserted) {
 		key.objectid = btrfs_ino(inode);
 		key.type = BTRFS_EXTENT_DATA_KEY;
 		key.offset = em->start;