1 From 1da6da1563df986dd35080d7edcf59b739696c40 Mon Sep 17 00:00:00 2001
2 From: Jan Kara <jack@suse.cz>
3 Date: Tue, 25 Nov 2014 11:55:24 -0500
4 Subject: [PATCH 7/7] ext4: introduce aging to extent status tree
6 Introduce a simple aging to extent status tree. Each extent has a
7 REFERENCED bit which gets set when the extent is used. Shrinker then
8 skips entries with referenced bit set and clears the bit. Thus
9 frequently used extents have higher chances of staying in memory.
11 Signed-off-by: Jan Kara <jack@suse.cz>
12 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
14 fs/ext4/extents_status.c | 22 +++++++++++++++++-----
15 fs/ext4/extents_status.h | 35 +++++++++++++++++++++++++++++++----
16 2 files changed, 48 insertions(+), 9 deletions(-)
18 diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
19 index a29708c0..0305f308 100644
20 --- a/fs/ext4/extents_status.c
21 +++ b/fs/ext4/extents_status.c
22 @@ -382,7 +382,7 @@ static void ext4_es_free_extent(struct inode *inode, struct extent_status *es)
23 static int ext4_es_can_be_merged(struct extent_status *es1,
24 struct extent_status *es2)
26 - if (ext4_es_status(es1) != ext4_es_status(es2))
27 + if (ext4_es_type(es1) != ext4_es_type(es2))
30 if (((__u64) es1->es_len) + es2->es_len > EXT_MAX_BLOCKS) {
31 @@ -425,6 +425,8 @@ ext4_es_try_to_merge_left(struct inode *inode, struct extent_status *es)
32 es1 = rb_entry(node, struct extent_status, rb_node);
33 if (ext4_es_can_be_merged(es1, es)) {
34 es1->es_len += es->es_len;
35 + if (ext4_es_is_referenced(es))
36 + ext4_es_set_referenced(es1);
37 rb_erase(&es->rb_node, &tree->root);
38 ext4_es_free_extent(inode, es);
40 @@ -447,6 +449,8 @@ ext4_es_try_to_merge_right(struct inode *inode, struct extent_status *es)
41 es1 = rb_entry(node, struct extent_status, rb_node);
42 if (ext4_es_can_be_merged(es, es1)) {
43 es->es_len += es1->es_len;
44 + if (ext4_es_is_referenced(es1))
45 + ext4_es_set_referenced(es);
46 rb_erase(node, &tree->root);
47 ext4_es_free_extent(inode, es1);
49 @@ -823,6 +827,8 @@ out:
50 es->es_lblk = es1->es_lblk;
51 es->es_len = es1->es_len;
52 es->es_pblk = es1->es_pblk;
53 + if (!ext4_es_is_referenced(es))
54 + ext4_es_set_referenced(es);
55 stats->es_stats_cache_hits++;
57 stats->es_stats_cache_misses++;
58 @@ -1243,11 +1249,17 @@ static int es_do_reclaim_extents(struct ext4_inode_info *ei, ext4_lblk_t end,
59 * We can't reclaim delayed extent from status tree because
60 * fiemap, bigallic, and seek_data/hole need to use it.
62 - if (!ext4_es_is_delayed(es)) {
63 - rb_erase(&es->rb_node, &tree->root);
64 - ext4_es_free_extent(inode, es);
66 + if (ext4_es_is_delayed(es))
68 + if (ext4_es_is_referenced(es)) {
69 + ext4_es_clear_referenced(es);
73 + rb_erase(&es->rb_node, &tree->root);
74 + ext4_es_free_extent(inode, es);
79 es = rb_entry(node, struct extent_status, rb_node);
80 diff --git a/fs/ext4/extents_status.h b/fs/ext4/extents_status.h
81 index e86b1f34..691b5261 100644
82 --- a/fs/ext4/extents_status.h
83 +++ b/fs/ext4/extents_status.h
84 @@ -34,6 +34,7 @@ enum {
92 @@ -44,6 +45,12 @@ enum {
93 #define EXTENT_STATUS_UNWRITTEN (1 << ES_UNWRITTEN_B)
94 #define EXTENT_STATUS_DELAYED (1 << ES_DELAYED_B)
95 #define EXTENT_STATUS_HOLE (1 << ES_HOLE_B)
96 +#define EXTENT_STATUS_REFERENCED (1 << ES_REFERENCED_B)
98 +#define ES_TYPE_MASK ((ext4_fsblk_t)(EXTENT_STATUS_WRITTEN | \
99 + EXTENT_STATUS_UNWRITTEN | \
100 + EXTENT_STATUS_DELAYED | \
101 + EXTENT_STATUS_HOLE) << ES_SHIFT)
105 @@ -93,24 +100,44 @@ static inline unsigned int ext4_es_status(struct extent_status *es)
106 return es->es_pblk >> ES_SHIFT;
109 +static inline unsigned int ext4_es_type(struct extent_status *es)
111 + return (es->es_pblk & ES_TYPE_MASK) >> ES_SHIFT;
114 static inline int ext4_es_is_written(struct extent_status *es)
116 - return (ext4_es_status(es) & EXTENT_STATUS_WRITTEN) != 0;
117 + return (ext4_es_type(es) & EXTENT_STATUS_WRITTEN) != 0;
120 static inline int ext4_es_is_unwritten(struct extent_status *es)
122 - return (ext4_es_status(es) & EXTENT_STATUS_UNWRITTEN) != 0;
123 + return (ext4_es_type(es) & EXTENT_STATUS_UNWRITTEN) != 0;
126 static inline int ext4_es_is_delayed(struct extent_status *es)
128 - return (ext4_es_status(es) & EXTENT_STATUS_DELAYED) != 0;
129 + return (ext4_es_type(es) & EXTENT_STATUS_DELAYED) != 0;
132 static inline int ext4_es_is_hole(struct extent_status *es)
134 - return (ext4_es_status(es) & EXTENT_STATUS_HOLE) != 0;
135 + return (ext4_es_type(es) & EXTENT_STATUS_HOLE) != 0;
138 +static inline void ext4_es_set_referenced(struct extent_status *es)
140 + es->es_pblk |= ((ext4_fsblk_t)EXTENT_STATUS_REFERENCED) << ES_SHIFT;
143 +static inline void ext4_es_clear_referenced(struct extent_status *es)
145 + es->es_pblk &= ~(((ext4_fsblk_t)EXTENT_STATUS_REFERENCED) << ES_SHIFT);
148 +static inline int ext4_es_is_referenced(struct extent_status *es)
150 + return (ext4_es_status(es) & EXTENT_STATUS_REFERENCED) != 0;
153 static inline ext4_fsblk_t ext4_es_pblock(struct extent_status *es)