[PATCH AUTOSEL 6.12 15/15] f2fs: add a sysfs node to limit max read extent count per-inode

Sasha Levin
2024-12-04T17:11:55Z

From: Chao Yu <chao@kernel.org>

[ Upstream commit 009a8241a8e5a14ea2dd0b8db42dbf283527dd44 ]

Quoted:
"at this time, there are still 1086911 extent nodes in this zombie
extent tree that need to be cleaned up.

crash_arm64_sprd_v8.0.3++> extent_tree.node_cnt ffffff80896cc500
node_cnt = {
counter = 1086911
},
"

As reported by Xiuhong, there will be a huge number of extent nodes
in extent tree, it may potentially cause:
- slab memory fragments
- extreme long time shrink on extent tree
- low mapping efficiency

Let's add a sysfs node to limit max read extent count for each inode,
by default, value of this threshold is 10240, it can be updated
according to user's requirement.

Reported-by: Xiuhong Wang <xiuhong.wang@unisoc.com>
Closes: https://lore.kernel.org/linux-f2fs-devel/20241112110627.1314632-1-xiuhong.wang@unisoc.com/
Signed-off-by: Xiuhong Wang <xiuhong.wang@unisoc.com>
Signed-off-by: Zhiguo Niu <zhiguo.niu@unisoc.com>
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
Documentation/ABI/testing/sysfs-fs-f2fs | 6 ++++++
fs/f2fs/extent_cache.c | 5 ++++-
fs/f2fs/f2fs.h | 4 ++++
fs/f2fs/sysfs.c | 10 ++++++++++
4 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
index fdedf1ea944ba..ccee0fd74dd66 100644
--- a/Documentation/ABI/testing/sysfs-fs-f2fs
+++ b/Documentation/ABI/testing/sysfs-fs-f2fs
@@ -819,3 +819,9 @@ Description: It controls the valid block ratio threshold not to trigger excessiv
for zoned deivces. The initial value of it is 95(%). F2FS will stop the
background GC thread from intiating GC for sections having valid blocks
exceeding the ratio.
+
+What: /sys/fs/f2fs/<disk>/max_read_extent_count
+Date: November 2024
+Contact: "Chao Yu" <chao@kernel.org>
+Description: It controls max read extent count for per-inode, the value of threshold
+ is 10240 by default.
diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
index 368d9cbdea743..fb09c8e9bc573 100644
--- a/fs/f2fs/extent_cache.c
+++ b/fs/f2fs/extent_cache.c
@@ -674,7 +674,9 @@ static void __update_extent_tree_range(struct inode *inode,
}

if (end < org_end && (type != EX_READ ||
- org_end - end >= F2FS_MIN_EXTENT_LEN)) {
+ (org_end - end >= F2FS_MIN_EXTENT_LEN &&
+ atomic_read(&et->node_cnt) <
+ sbi->max_read_extent_count))) {
if (parts) {
__set_extent_info(&ei,
end, org_end - end,
@@ -1169,6 +1171,7 @@ void f2fs_init_extent_cache_info(struct f2fs_sb_info *sbi)
sbi->hot_data_age_threshold = DEF_HOT_DATA_AGE_THRESHOLD;
sbi->warm_data_age_threshold = DEF_WARM_DATA_AGE_THRESHOLD;
sbi->last_age_weight = LAST_AGE_WEIGHT;
+ sbi->max_read_extent_count = DEF_MAX_READ_EXTENT_COUNT;
}

int __init f2fs_create_extent_cache(void)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 33f5449dc22d5..928c10dc7ad58 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -634,6 +634,9 @@ enum {
#define DEF_HOT_DATA_AGE_THRESHOLD 262144
#define DEF_WARM_DATA_AGE_THRESHOLD 2621440

+/* default max read extent count per inode */
+#define DEF_MAX_READ_EXTENT_COUNT 10240
+
/* extent cache type */
enum extent_type {
EX_READ,
@@ -1619,6 +1622,7 @@ struct f2fs_sb_info {
/* for extent tree cache */
struct extent_tree_info extent_tree[NR_EXTENT_CACHES];
atomic64_t allocated_data_blocks; /* for block age extent_cache */
+ unsigned int max_read_extent_count; /* max read extent count per inode */

/* The threshold used for hot and warm data seperation*/
unsigned int hot_data_age_threshold;
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index c56e8c8739352..d9a44f03e558b 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -789,6 +789,13 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
return count;
}

+ if (!strcmp(a->attr.name, "max_read_extent_count")) {
+ if (t > UINT_MAX)
+ return -EINVAL;
+ *ui = (unsigned int)t;
+ return count;
+ }
+
if (!strcmp(a->attr.name, "ipu_policy")) {
if (t >= BIT(F2FS_IPU_MAX))
return -EINVAL;
@@ -1054,6 +1061,8 @@ F2FS_SBI_GENERAL_RW_ATTR(revoked_atomic_block);
F2FS_SBI_GENERAL_RW_ATTR(hot_data_age_threshold);
F2FS_SBI_GENERAL_RW_ATTR(warm_data_age_threshold);
F2FS_SBI_GENERAL_RW_ATTR(last_age_weight);
+/* read extent cache */
+F2FS_SBI_GENERAL_RW_ATTR(max_read_extent_count);
#ifdef CONFIG_BLK_DEV_ZONED
F2FS_SBI_GENERAL_RO_ATTR(unusable_blocks_per_sec);
F2FS_SBI_GENERAL_RW_ATTR(blkzone_alloc_policy);
@@ -1244,6 +1253,7 @@ static struct attribute *f2fs_attrs[] = {
ATTR_LIST(hot_data_age_threshold),
ATTR_LIST(warm_data_age_threshold),
ATTR_LIST(last_age_weight),
+ ATTR_LIST(max_read_extent_count),
NULL,
};
ATTRIBUTE_GROUPS(f2fs);
--
2.43.0