On 2/1/25 06:27, Jaegeuk Kim via Linux-f2fs-devel wrote:
> 1. ioctl(fd1, F2FS_IOC_DONATE_RANGE, {0,3});
> 2. ioctl(fd2, F2FS_IOC_DONATE_RANGE, {1,2});
> 3. ioctl(fd3, F2FS_IOC_DONATE_RANGE, {3,1});
> 4. echo 1024 > /sys/fs/f2fs/tuning/reclaim_caches_kb
>
> This gives a way to reclaim file-backed pages by iterating all f2fs mounts
> until
> reclaiming 1MB page cache ranges, registered by #1, #2, and #3.
>
> 5. cat /sys/fs/f2fs/tuning/reclaim_caches_kb
> -> gives total number of registered file ranges.
>
> Signed-off-by: Jaegeuk Kim <jaeg...@kernel.org>
> ---
> Documentation/ABI/testing/sysfs-fs-f2fs | 7 ++
> fs/f2fs/f2fs.h | 2 +
> fs/f2fs/shrinker.c | 90 +++++++++++++++++++++++++
> fs/f2fs/sysfs.c | 63 +++++++++++++++++
> 4 files changed, 162 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs
> b/Documentation/ABI/testing/sysfs-fs-f2fs
> index 3e1630c70d8a..81deae2af84d 100644
> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
> @@ -828,3 +828,10 @@ Date: November 2024
> Contact: "Chao Yu" <c...@kernel.org>
> Description: It controls max read extent count for per-inode, the value of
> threshold
> is 10240 by default.
> +
> +What: /sys/fs/f2fs/tuning/reclaim_caches_kb
> +Date: February 2025
> +Contact: "Jaegeuk Kim" <jaeg...@kernel.org>
> +Description: It reclaims the given KBs of file-backed pages registered by
> + ioctl(F2FS_IOC_DONATE_RANGE).
> + For example, writing N tries to drop N KBs spaces in LRU.
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 805585a7d2b6..bd0d8138b71d 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -4241,6 +4241,8 @@ unsigned long f2fs_shrink_count(struct shrinker *shrink,
> struct shrink_control *sc);
> unsigned long f2fs_shrink_scan(struct shrinker *shrink,
> struct shrink_control *sc);
> +unsigned int f2fs_donate_files(void);
> +void f2fs_reclaim_caches(unsigned int reclaim_caches_kb);
> void f2fs_join_shrinker(struct f2fs_sb_info *sbi);
> void f2fs_leave_shrinker(struct f2fs_sb_info *sbi);
>
> diff --git a/fs/f2fs/shrinker.c b/fs/f2fs/shrinker.c
> index 83d6fb97dcae..45efff635d8e 100644
> --- a/fs/f2fs/shrinker.c
> +++ b/fs/f2fs/shrinker.c
> @@ -130,6 +130,96 @@ unsigned long f2fs_shrink_scan(struct shrinker *shrink,
> return freed;
> }
>
> +unsigned int f2fs_donate_files(void)
> +{
> + struct f2fs_sb_info *sbi;
> + struct list_head *p;
> + unsigned int donate_files = 0;
> +
> + spin_lock(&f2fs_list_lock);
> + p = f2fs_list.next;
> + while (p != &f2fs_list) {
> + sbi = list_entry(p, struct f2fs_sb_info, s_list);
> +
> + /* stop f2fs_put_super */
> + if (!mutex_trylock(&sbi->umount_mutex)) {
> + p = p->next;
> + continue;
> + }
> + spin_unlock(&f2fs_list_lock);
> +
> + donate_files += sbi->donate_files;
> +
> + spin_lock(&f2fs_list_lock);
> + p = p->next;
> + mutex_unlock(&sbi->umount_mutex);
> + }
> + spin_unlock(&f2fs_list_lock);
> +
> + return donate_files;
> +}
> +
> +static unsigned int do_reclaim_caches(struct f2fs_sb_info *sbi,
> + unsigned int reclaim_caches_kb)
> +{
> + struct inode *inode;
> + struct f2fs_inode_info *fi;
> + unsigned int nfiles = sbi->donate_files;
> + pgoff_t npages = reclaim_caches_kb >> (PAGE_SHIFT - 10);
> +
> + while (npages && nfiles--) {
> + pgoff_t len;
> +
> + spin_lock(&sbi->inode_lock[DONATE_INODE]);
> + if (list_empty(&sbi->inode_list[DONATE_INODE])) {
> + spin_unlock(&sbi->inode_lock[DONATE_INODE]);
> + break;
> + }
> + fi = list_first_entry(&sbi->inode_list[DONATE_INODE],
> + struct f2fs_inode_info, gdonate_list);
> + list_move_tail(&fi->gdonate_list,
> &sbi->inode_list[DONATE_INODE]);
> + inode = igrab(&fi->vfs_inode);
> + spin_unlock(&sbi->inode_lock[DONATE_INODE]);
> +
> + if (!inode)
> + continue;
> +
> + len = fi->donate_end - fi->donate_start + 1;
> + npages = npages < len ? 0 : npages - len;
> + invalidate_inode_pages2_range(inode->i_mapping,
> + fi->donate_start, fi->donate_end);
> + iput(inode);
> + cond_resched();
> + }
> + return npages << (PAGE_SHIFT - 10);
> +}
> +
> +void f2fs_reclaim_caches(unsigned int reclaim_caches_kb)
> +{
> + struct f2fs_sb_info *sbi;
> + struct list_head *p;
> +
> + spin_lock(&f2fs_list_lock);
> + p = f2fs_list.next;
> + while (p != &f2fs_list && reclaim_caches_kb) {
> + sbi = list_entry(p, struct f2fs_sb_info, s_list);
> +
> + /* stop f2fs_put_super */
> + if (!mutex_trylock(&sbi->umount_mutex)) {
> + p = p->next;
> + continue;
> + }
> + spin_unlock(&f2fs_list_lock);
> +
> + reclaim_caches_kb = do_reclaim_caches(sbi, reclaim_caches_kb);
> +
> + spin_lock(&f2fs_list_lock);
> + p = p->next;
> + mutex_unlock(&sbi->umount_mutex);
> + }
> + spin_unlock(&f2fs_list_lock);
> +}
> +
> void f2fs_join_shrinker(struct f2fs_sb_info *sbi)
> {
> spin_lock(&f2fs_list_lock);
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index 4bd7b17a20c8..579226a05a69 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -916,6 +916,39 @@ static struct f2fs_base_attr f2fs_base_attr_##_name = {
> \
> .show = f2fs_feature_show, \
> }
>
> +static ssize_t f2fs_tune_show(struct f2fs_base_attr *a, char *buf)
> +{
> + unsigned int res;
> +
> + if (!strcmp(a->attr.name, "reclaim_caches_kb"))
> + res = f2fs_donate_files();
> +
> + return sysfs_emit(buf, "%u\n", res);
> +}
> +
> +static ssize_t f2fs_tune_store(struct f2fs_base_attr *a,
> + const char *buf, size_t count)
> +{
> + unsigned long t;
> + int ret;
> +
> + ret = kstrtoul(skip_spaces(buf), 0, &t);
> + if (ret)
> + return ret;
> +
> + if (!strcmp(a->attr.name, "reclaim_caches_kb"))
> + f2fs_reclaim_caches(t);
> +
> + return ret ? ret : count;
return count;
Thanks,
> +}
> +
> +#define F2FS_TUNE_RW_ATTR(_name) \
> +static struct f2fs_base_attr f2fs_base_attr_##_name = { \
> + .attr = {.name = __stringify(_name), .mode = 0644 }, \
> + .show = f2fs_tune_show, \
> + .store = f2fs_tune_store, \
> +}
> +
> static ssize_t f2fs_sb_feature_show(struct f2fs_attr *a,
> struct f2fs_sb_info *sbi, char *buf)
> {
> @@ -1368,6 +1401,14 @@ static struct attribute *f2fs_sb_feat_attrs[] = {
> };
> ATTRIBUTE_GROUPS(f2fs_sb_feat);
>
> +F2FS_TUNE_RW_ATTR(reclaim_caches_kb);
> +
> +static struct attribute *f2fs_tune_attrs[] = {
> + BASE_ATTR_LIST(reclaim_caches_kb),
> + NULL,
> +};
> +ATTRIBUTE_GROUPS(f2fs_tune);
> +
> static const struct sysfs_ops f2fs_attr_ops = {
> .show = f2fs_attr_show,
> .store = f2fs_attr_store,
> @@ -1401,6 +1442,20 @@ static struct kobject f2fs_feat = {
> .kset = &f2fs_kset,
> };
>
> +static const struct sysfs_ops f2fs_tune_attr_ops = {
> + .show = f2fs_base_attr_show,
> + .store = f2fs_base_attr_store,
> +};
> +
> +static const struct kobj_type f2fs_tune_ktype = {
> + .default_groups = f2fs_tune_groups,
> + .sysfs_ops = &f2fs_tune_attr_ops,
> +};
> +
> +static struct kobject f2fs_tune = {
> + .kset = &f2fs_kset,
> +};
> +
> static ssize_t f2fs_stat_attr_show(struct kobject *kobj,
> struct attribute *attr, char *buf)
> {
> @@ -1637,6 +1692,11 @@ int __init f2fs_init_sysfs(void)
> if (ret)
> goto unregister_out;
>
> + ret = kobject_init_and_add(&f2fs_tune, &f2fs_tune_ktype,
> + NULL, "tuning");
> + if (ret)
> + goto put_feat;
> +
> f2fs_proc_root = proc_mkdir("fs/f2fs", NULL);
> if (!f2fs_proc_root) {
> ret = -ENOMEM;
> @@ -1645,6 +1705,8 @@ int __init f2fs_init_sysfs(void)
>
> return 0;
> put_kobject:
> + kobject_put(&f2fs_tune);
> +put_feat:
> kobject_put(&f2fs_feat);
> unregister_out:
> kset_unregister(&f2fs_kset);
> @@ -1653,6 +1715,7 @@ int __init f2fs_init_sysfs(void)
>
> void f2fs_exit_sysfs(void)
> {
> + kobject_put(&f2fs_tune);
> kobject_put(&f2fs_feat);
> kset_unregister(&f2fs_kset);
> remove_proc_entry("fs/f2fs", NULL);
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