btrfs: move btrfs_drop_extent_cache() to extent_map.c

The function btrfs_drop_extent_cache() doesn't really belong at file.c
because what it does is drop a range of extent maps for a file range.
It directly allocates and manipulates extent maps, by dropping,
splitting and replacing them in an extent map tree, so it should be
located at extent_map.c, where all manipulations of an extent map tree
and its extent maps are supposed to be done.

So move it out of file.c and into extent_map.c. Additionally do the
following changes:

1) Rename it into btrfs_drop_extent_map_range(), as this makes it more
   clear about what it does. The term "cache" is a bit confusing as it's
   not widely used, "extent maps" or "extent mapping" is much more common;

2) Change its 'skip_pinned' argument from int to bool;

3) Turn several of its local variables from int to bool, since they are
   used as booleans;

4) Move the declaration of some variables out of the function's main
   scope and into the scopes where they are used;

5) Remove pointless assignment of false to 'modified' early in the while
   loop, as later that variable is set and it's not used before that
   second assignment;

6) Remove checks for NULL before calling free_extent_map().

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, 3 insertions, 187 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 8786b2b8f0a1..d8a8c849584d 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -499,190 +499,6 @@ int btrfs_dirty_pages(struct btrfs_inode *inode, struct page **pages,
 }
 
 /*
- * this drops all the extents in the cache that intersect the range
- * [start, end].  Existing extents are split as required.
- */
-void btrfs_drop_extent_cache(struct btrfs_inode *inode, u64 start, u64 end,
-			     int skip_pinned)
-{
-	struct extent_map *em;
-	struct extent_map *split = NULL;
-	struct extent_map *split2 = NULL;
-	struct extent_map_tree *em_tree = &inode->extent_tree;
-	u64 len = end - start + 1;
-	u64 gen;
-	int ret;
-	int testend = 1;
-	unsigned long flags;
-	int compressed = 0;
-	bool modified;
-
-	WARN_ON(end < start);
-	if (end == (u64)-1) {
-		len = (u64)-1;
-		testend = 0;
-	}
-	while (1) {
-		bool ends_after_range = false;
-		int no_splits = 0;
-
-		modified = false;
-		if (!split)
-			split = alloc_extent_map();
-		if (!split2)
-			split2 = alloc_extent_map();
-		if (!split || !split2)
-			no_splits = 1;
-
-		write_lock(&em_tree->lock);
-		em = lookup_extent_mapping(em_tree, start, len);
-		if (!em) {
-			write_unlock(&em_tree->lock);
-			break;
-		}
-		if (testend && em->start + em->len > start + len)
-			ends_after_range = true;
-		flags = em->flags;
-		gen = em->generation;
-		if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
-			if (ends_after_range) {
-				free_extent_map(em);
-				write_unlock(&em_tree->lock);
-				break;
-			}
-			start = em->start + em->len;
-			if (testend)
-				len = start + len - (em->start + em->len);
-			free_extent_map(em);
-			write_unlock(&em_tree->lock);
-			continue;
-		}
-		compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
-		clear_bit(EXTENT_FLAG_PINNED, &em->flags);
-		clear_bit(EXTENT_FLAG_LOGGING, &flags);
-		modified = !list_empty(&em->list);
-		if (no_splits)
-			goto next;
-
-		if (em->start < start) {
-			split->start = em->start;
-			split->len = start - em->start;
-
-			if (em->block_start < EXTENT_MAP_LAST_BYTE) {
-				split->orig_start = em->orig_start;
-				split->block_start = em->block_start;
-
-				if (compressed)
-					split->block_len = em->block_len;
-				else
-					split->block_len = split->len;
-				split->orig_block_len = max(split->block_len,
-						em->orig_block_len);
-				split->ram_bytes = em->ram_bytes;
-			} else {
-				split->orig_start = split->start;
-				split->block_len = 0;
-				split->block_start = em->block_start;
-				split->orig_block_len = 0;
-				split->ram_bytes = split->len;
-			}
-
-			split->generation = gen;
-			split->flags = flags;
-			split->compress_type = em->compress_type;
-			replace_extent_mapping(em_tree, em, split, modified);
-			free_extent_map(split);
-			split = split2;
-			split2 = NULL;
-		}
-		if (ends_after_range) {
-			u64 diff = start + len - em->start;
-
-			split->start = start + len;
-			split->len = em->start + em->len - (start + len);
-			split->flags = flags;
-			split->compress_type = em->compress_type;
-			split->generation = gen;
-
-			if (em->block_start < EXTENT_MAP_LAST_BYTE) {
-				split->orig_block_len = max(em->block_len,
-						    em->orig_block_len);
-
-				split->ram_bytes = em->ram_bytes;
-				if (compressed) {
-					split->block_len = em->block_len;
-					split->block_start = em->block_start;
-					split->orig_start = em->orig_start;
-				} else {
-					split->block_len = split->len;
-					split->block_start = em->block_start
-						+ diff;
-					split->orig_start = em->orig_start;
-				}
-			} else {
-				split->ram_bytes = split->len;
-				split->orig_start = split->start;
-				split->block_len = 0;
-				split->block_start = em->block_start;
-				split->orig_block_len = 0;
-			}
-
-			if (extent_map_in_tree(em)) {
-				replace_extent_mapping(em_tree, em, split,
-						       modified);
-			} else {
-				ret = add_extent_mapping(em_tree, split,
-							 modified);
-				/* Logic error, shouldn't happen. */
-				ASSERT(ret == 0);
-				if (WARN_ON(ret != 0) && modified)
-					btrfs_set_inode_full_sync(inode);
-			}
-			free_extent_map(split);
-			split = NULL;
-		}
-next:
-		if (extent_map_in_tree(em)) {
-			/*
-			 * If the extent map is still in the tree it means that
-			 * either of the following is true:
-			 *
-			 * 1) It fits entirely in our range (doesn't end beyond
-			 *    it or starts before it);
-			 *
-			 * 2) It starts before our range and/or ends after our
-			 *    range, and we were not able to allocate the extent
-			 *    maps for split operations, @split and @split2.
-			 *
-			 * If we are at case 2) then we just remove the entire
-			 * extent map - this is fine since if anyone needs it to
-			 * access the subranges outside our range, will just
-			 * load it again from the subvolume tree's file extent
-			 * item. However if the extent map was in the list of
-			 * modified extents, then we must mark the inode for a
-			 * full fsync, otherwise a fast fsync will miss this
-			 * extent if it's new and needs to be logged.
-			 */
-			if ((em->start < start || ends_after_range) && modified) {
-				ASSERT(no_splits);
-				btrfs_set_inode_full_sync(inode);
-			}
-			remove_extent_mapping(em_tree, em);
-		}
-		write_unlock(&em_tree->lock);
-
-		/* once for us */
-		free_extent_map(em);
-		/* once for the tree*/
-		free_extent_map(em);
-	}
-	if (split)
-		free_extent_map(split);
-	if (split2)
-		free_extent_map(split2);
-}
-
-/*
  * this is very complex, but the basic idea is to drop all extents
  * in the range start - end.  hint_block is filled in with a block number
  * that would be a good hint to the block allocator for this file.
@@ -739,7 +555,7 @@ int btrfs_drop_extents(struct btrfs_trans_handle *trans,
 	}
 
 	if (args->drop_cache)
-		btrfs_drop_extent_cache(inode, args->start, args->end - 1, 0);
+		btrfs_drop_extent_map_range(inode, args->start, args->end - 1, false);
 
 	if (args->start >= inode->disk_i_size && !args->replace_extent)
 		modify_tree = 0;
@@ -2610,7 +2426,7 @@ out:
 
 	hole_em = alloc_extent_map();
 	if (!hole_em) {
-		btrfs_drop_extent_cache(inode, offset, end - 1, 0);
+		btrfs_drop_extent_map_range(inode, offset, end - 1, false);
 		btrfs_set_inode_full_sync(inode);
 	} else {
 		hole_em->start = offset;
@@ -2625,7 +2441,7 @@ out:
 		hole_em->generation = trans->transid;
 
 		do {
-			btrfs_drop_extent_cache(inode, offset, end - 1, 0);
+			btrfs_drop_extent_map_range(inode, offset, end - 1, false);
 			write_lock(&em_tree->lock);
 			ret = add_extent_mapping(em_tree, hole_em, 1);
 			write_unlock(&em_tree->lock);