diff options
Diffstat (limited to 'fs/btrfs/super.c')
| -rw-r--r-- | fs/btrfs/super.c | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 83478deada3b..98fa0f382480 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -28,6 +28,7 @@ #include <linux/btrfs.h> #include <linux/security.h> #include <linux/fs_parser.h> +#include <linux/swap.h> #include "messages.h" #include "delayed-inode.h" #include "ctree.h" @@ -2401,7 +2402,13 @@ static long btrfs_nr_cached_objects(struct super_block *sb, struct shrink_contro trace_btrfs_extent_map_shrinker_count(fs_info, nr); - return nr; + /* + * Only report the real number for DEBUG builds, as there are reports of + * serious performance degradation caused by too frequent shrinks. + */ + if (IS_ENABLED(CONFIG_BTRFS_DEBUG)) + return nr; + return 0; } static long btrfs_free_cached_objects(struct super_block *sb, struct shrink_control *sc) @@ -2409,6 +2416,15 @@ static long btrfs_free_cached_objects(struct super_block *sb, struct shrink_cont const long nr_to_scan = min_t(unsigned long, LONG_MAX, sc->nr_to_scan); struct btrfs_fs_info *fs_info = btrfs_sb(sb); + /* + * We may be called from any task trying to allocate memory and we don't + * want to slow it down with scanning and dropping extent maps. It would + * also cause heavy lock contention if many tasks concurrently enter + * here. Therefore only allow kswapd tasks to scan and drop extent maps. + */ + if (!current_is_kswapd()) + return 0; + return btrfs_free_extent_maps(fs_info, nr_to_scan); } |