ext4: move handling of list of shrinkable inodes into extent status code

Currently callers adding extents to extent status tree were responsible
for adding the inode to the list of inodes with freeable extents. This
is error prone and puts list handling in unnecessarily many places.

Just add inode to the list automatically when the first non-delay extent
is added to the tree and remove inode from the list when the last
non-delay extent is removed.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/extents.c

@@ -4632,7 +4632,6 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
 
 	trace_ext4_ext_map_blocks_exit(inode, flags, map,
 				       err ? err : allocated);
-	ext4_es_list_add(inode);
 	return err ? err : allocated;
 }
 
@@ -5191,7 +5190,6 @@ int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		error = ext4_fill_fiemap_extents(inode, start_blk,
 						 len_blks, fieinfo);
 	}
-	ext4_es_list_add(inode);
 	return error;
 }
 

fs/ext4/extents_status.c

@@ -298,7 +298,7 @@ void ext4_es_find_delayed_extent_range(struct inode *inode,
 	trace_ext4_es_find_delayed_extent_range_exit(inode, es);
 }
 
-void ext4_es_list_add(struct inode *inode)
+static void ext4_es_list_add(struct inode *inode)
 {
 	struct ext4_inode_info *ei = EXT4_I(inode);
 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
@@ -314,7 +314,7 @@ void ext4_es_list_add(struct inode *inode)
 	spin_unlock(&sbi->s_es_lock);
 }
 
-void ext4_es_list_del(struct inode *inode)
+static void ext4_es_list_del(struct inode *inode)
 {
 	struct ext4_inode_info *ei = EXT4_I(inode);
 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
@@ -344,7 +344,8 @@ ext4_es_alloc_extent(struct inode *inode, ext4_lblk_t lblk, ext4_lblk_t len,
 	 * We don't count delayed extent because we never try to reclaim them
 	 */
 	if (!ext4_es_is_delayed(es)) {
-		EXT4_I(inode)->i_es_shk_nr++;
+		if (!EXT4_I(inode)->i_es_shk_nr++)
+			ext4_es_list_add(inode);
 		percpu_counter_inc(&EXT4_SB(inode->i_sb)->
 					s_es_stats.es_stats_shk_cnt);
 	}
@@ -363,7 +364,8 @@ static void ext4_es_free_extent(struct inode *inode, struct extent_status *es)
 	/* Decrease the shrink counter when this es is not delayed */
 	if (!ext4_es_is_delayed(es)) {
 		BUG_ON(EXT4_I(inode)->i_es_shk_nr == 0);
-		EXT4_I(inode)->i_es_shk_nr--;
+		if (!--EXT4_I(inode)->i_es_shk_nr)
+			ext4_es_list_del(inode);
 		percpu_counter_dec(&EXT4_SB(inode->i_sb)->
 					s_es_stats.es_stats_shk_cnt);
 	}

fs/ext4/extents_status.h

@@ -150,7 +150,5 @@ static inline void ext4_es_store_pblock_status(struct extent_status *es,
 
 extern int ext4_es_register_shrinker(struct ext4_sb_info *sbi);
 extern void ext4_es_unregister_shrinker(struct ext4_sb_info *sbi);
-extern void ext4_es_list_add(struct inode *inode);
-extern void ext4_es_list_del(struct inode *inode);
 
 #endif /* _EXT4_EXTENTS_STATUS_H */

fs/ext4/inode.c

@@ -486,7 +486,6 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
 
 	/* Lookup extent status tree firstly */
 	if (ext4_es_lookup_extent(inode, map->m_lblk, &es)) {
-		ext4_es_list_add(inode);
 		if (ext4_es_is_written(&es) || ext4_es_is_unwritten(&es)) {
 			map->m_pblk = ext4_es_pblock(&es) +
 					map->m_lblk - es.es_lblk;
@@ -1388,7 +1387,6 @@ static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
 
 	/* Lookup extent status tree firstly */
 	if (ext4_es_lookup_extent(inode, iblock, &es)) {
-		ext4_es_list_add(inode);
 		if (ext4_es_is_hole(&es)) {
 			retval = 0;
 			down_read(&EXT4_I(inode)->i_data_sem);

fs/ext4/ioctl.c

@@ -78,8 +78,6 @@ static void swap_inode_data(struct inode *inode1, struct inode *inode2)
 	memswap(&ei1->i_disksize, &ei2->i_disksize, sizeof(ei1->i_disksize));
 	ext4_es_remove_extent(inode1, 0, EXT_MAX_BLOCKS);
 	ext4_es_remove_extent(inode2, 0, EXT_MAX_BLOCKS);
-	ext4_es_list_del(inode1);
-	ext4_es_list_del(inode2);
 
 	isize = i_size_read(inode1);
 	i_size_write(inode1, i_size_read(inode2));

fs/ext4/super.c

@@ -962,7 +962,6 @@ void ext4_clear_inode(struct inode *inode)
 	dquot_drop(inode);
 	ext4_discard_preallocations(inode);
 	ext4_es_remove_extent(inode, 0, EXT_MAX_BLOCKS);
-	ext4_es_list_del(inode);
 	if (EXT4_I(inode)->jinode) {
 		jbd2_journal_release_jbd_inode(EXT4_JOURNAL(inode),
 					       EXT4_I(inode)->jinode);