[PATCH 0/2 v5] add ioctl/sysfs to donate file-backed pages

[PATCH 0/2 v5] add ioctl/sysfs to donate file-backed pages

[Jaegeuk Kim]

If users clearly know which file-backed pages to reclaim in system view, they
can use this ioctl() to register in advance and reclaim all at once later.

Change log from v4:
 - fix range handling

Change log from v3:
 - cover partial range

Change log from v2:
 - add more boundary checks
 - de-register the range, if len is zero

Jaegeuk Kim (1):
  f2fs: add a sysfs entry to request donate file-backed pages

Yi Sun (1):
  f2fs: Optimize f2fs_truncate_data_blocks_range()

 Documentation/ABI/testing/sysfs-fs-f2fs |  7 ++++++
 fs/f2fs/f2fs.h                          |  2 ++
 fs/f2fs/file.c                          | 29 +++++++++++++++++++++----
 fs/f2fs/shrinker.c                      | 27 +++++++++++++++++++++++
 fs/f2fs/sysfs.c                         |  8 +++++++
 5 files changed, 69 insertions(+), 4 deletions(-)

-- 
2.48.0.rc2.279.g1de40edade-goog

[PATCH 1/2] f2fs: add a sysfs entry to request donate file-backed pages

[Jaegeuk Kim]

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 3 > /sys/fs/f2fs/blk/donate_caches

will reclaim 3 page cache ranges, registered by #1, #2, and #3.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 Documentation/ABI/testing/sysfs-fs-f2fs |  7 +++++++
 fs/f2fs/f2fs.h                          |  2 ++
 fs/f2fs/shrinker.c                      | 27 +++++++++++++++++++++++++
 fs/f2fs/sysfs.c                         |  8 ++++++++
 4 files changed, 44 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
index 3e1630c70d8a..6f9d8b8889fd 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" <chao@kernel.org>
 Description:	It controls max read extent count for per-inode, the value of threshold
 		is 10240 by default.
+
+What:		/sys/fs/f2fs/<disk>/donate_caches
+Date:		December 2024
+Contact:	"Jaegeuk Kim" <jaegeuk@kernel.org>
+Description:	It reclaims the certian file-backed pages registered by
+		ioctl(F2FS_IOC_DONATE_RANGE).
+		For example, writing N tries to drop N address spaces in LRU.
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 951fbc3f94c7..399ddd10a94f 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1637,6 +1637,7 @@ struct f2fs_sb_info {
 
 	/* control donate caches */
 	unsigned int donate_files;
+	unsigned int donate_caches;
 
 	/* basic filesystem units */
 	unsigned int log_sectors_per_block;	/* log2 sectors per block */
@@ -4259,6 +4260,7 @@ unsigned long f2fs_shrink_count(struct shrinker *shrink,
 			struct shrink_control *sc);
 unsigned long f2fs_shrink_scan(struct shrinker *shrink,
 			struct shrink_control *sc);
+void f2fs_donate_caches(struct f2fs_sb_info *sbi);
 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..22f62813910b 100644
--- a/fs/f2fs/shrinker.c
+++ b/fs/f2fs/shrinker.c
@@ -130,6 +130,33 @@ unsigned long f2fs_shrink_scan(struct shrinker *shrink,
 	return freed;
 }
 
+void f2fs_donate_caches(struct f2fs_sb_info *sbi)
+{
+	struct inode *inode;
+	struct f2fs_inode_info *fi;
+	int nfiles = sbi->donate_caches;
+
+	while (nfiles--) {
+		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;
+
+		invalidate_inode_pages2_range(inode->i_mapping,
+					fi->donate_start, fi->donate_end);
+		iput(inode);
+	}
+}
+
 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 6b99dc49f776..f81190fabdd3 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -811,6 +811,12 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
 		return count;
 	}
 
+	if (!strcmp(a->attr.name, "donate_caches")) {
+		sbi->donate_caches = min(t, sbi->donate_files);
+		f2fs_donate_caches(sbi);
+		return count;
+	}
+
 	*ui = (unsigned int)t;
 
 	return count;
@@ -1030,6 +1036,7 @@ F2FS_SBI_GENERAL_RW_ATTR(max_victim_search);
 F2FS_SBI_GENERAL_RW_ATTR(migration_granularity);
 F2FS_SBI_GENERAL_RW_ATTR(migration_window_granularity);
 F2FS_SBI_GENERAL_RW_ATTR(dir_level);
+F2FS_SBI_GENERAL_RW_ATTR(donate_caches);
 #ifdef CONFIG_F2FS_IOSTAT
 F2FS_SBI_GENERAL_RW_ATTR(iostat_enable);
 F2FS_SBI_GENERAL_RW_ATTR(iostat_period_ms);
@@ -1178,6 +1185,7 @@ static struct attribute *f2fs_attrs[] = {
 	ATTR_LIST(migration_granularity),
 	ATTR_LIST(migration_window_granularity),
 	ATTR_LIST(dir_level),
+	ATTR_LIST(donate_caches),
 	ATTR_LIST(ram_thresh),
 	ATTR_LIST(ra_nid_pages),
 	ATTR_LIST(dirty_nats_ratio),
-- 
2.48.0.rc2.279.g1de40edade-goog

[PATCH 2/2] f2fs: Optimize f2fs_truncate_data_blocks_range()

[Jaegeuk Kim]

From: Yi Sun <yi.sun@unisoc.com>

Function f2fs_invalidate_blocks() can process consecutive
blocks at a time, so f2fs_truncate_data_blocks_range() is
optimized to use the new functionality of
f2fs_invalidate_blocks().

Add two variables @blkstart and @blklen, @blkstart records
the first address of the consecutive blocks, and @blkstart
records the number of consecutive blocks.

Signed-off-by: Yi Sun <yi.sun@unisoc.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 fs/f2fs/file.c | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 902f8f50cc27..6572970a988a 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -621,8 +621,11 @@ void f2fs_truncate_data_blocks_range(struct dnode_of_data *dn, int count)
 	int cluster_index = 0, valid_blocks = 0;
 	int cluster_size = F2FS_I(dn->inode)->i_cluster_size;
 	bool released = !atomic_read(&F2FS_I(dn->inode)->i_compr_blocks);
+	block_t blkstart;
+	int blklen = 0;
 
 	addr = get_dnode_addr(dn->inode, dn->node_page) + ofs;
+	blkstart = le32_to_cpu(*addr);
 
 	/* Assumption: truncation starts with cluster */
 	for (; count > 0; count--, addr++, dn->ofs_in_node++, cluster_index++) {
@@ -638,26 +641,44 @@ void f2fs_truncate_data_blocks_range(struct dnode_of_data *dn, int count)
 		}
 
 		if (blkaddr == NULL_ADDR)
-			continue;
+			goto next;
 
 		f2fs_set_data_blkaddr(dn, NULL_ADDR);
 
 		if (__is_valid_data_blkaddr(blkaddr)) {
 			if (time_to_inject(sbi, FAULT_BLKADDR_CONSISTENCE))
-				continue;
+				goto next;
 			if (!f2fs_is_valid_blkaddr_raw(sbi, blkaddr,
 						DATA_GENERIC_ENHANCE))
-				continue;
+				goto next;
 			if (compressed_cluster)
 				valid_blocks++;
 		}
 
-		f2fs_invalidate_blocks(sbi, blkaddr, 1);
+		if (blkstart + blklen == blkaddr) {
+			blklen++;
+		} else {
+			f2fs_invalidate_blocks(sbi, blkstart, blklen);
+			blkstart = blkaddr;
+			blklen = 1;
+		}
 
 		if (!released || blkaddr != COMPRESS_ADDR)
 			nr_free++;
+
+		continue;
+
+next:
+		if (blklen)
+			f2fs_invalidate_blocks(sbi, blkstart, blklen);
+
+		blkstart = le32_to_cpu(*(addr + 1));
+		blklen = 0;
 	}
 
+	if (blklen)
+		f2fs_invalidate_blocks(sbi, blkstart, blklen);
+
 	if (compressed_cluster)
 		f2fs_i_compr_blocks_update(dn->inode, valid_blocks, false);
 
-- 
2.48.0.rc2.279.g1de40edade-goog

Re: [PATCH 0/2 v5] add ioctl/sysfs to donate file-backed pages

[Christoph Hellwig]

Still NAC for sneaking in an almost undocumented MM feature into
a file system ioctl.  Especially while a discussion on that is still
ongoin.

And it's still bad that you don't even bother to Cc fsdevel on this,
nor linux-api or in this case the mm list.

On Thu, Jan 16, 2025 at 05:19:42PM +0000, Jaegeuk Kim wrote:
> If users clearly know which file-backed pages to reclaim in system view, they
> can use this ioctl() to register in advance and reclaim all at once later.
> 
> Change log from v4:
>  - fix range handling
> 
> Change log from v3:
>  - cover partial range
> 
> Change log from v2:
>  - add more boundary checks
>  - de-register the range, if len is zero
> 
> Jaegeuk Kim (1):
>   f2fs: add a sysfs entry to request donate file-backed pages
> 
> Yi Sun (1):
>   f2fs: Optimize f2fs_truncate_data_blocks_range()
> 
>  Documentation/ABI/testing/sysfs-fs-f2fs |  7 ++++++
>  fs/f2fs/f2fs.h                          |  2 ++
>  fs/f2fs/file.c                          | 29 +++++++++++++++++++++----
>  fs/f2fs/shrinker.c                      | 27 +++++++++++++++++++++++
>  fs/f2fs/sysfs.c                         |  8 +++++++
>  5 files changed, 69 insertions(+), 4 deletions(-)
> 
> -- 
> 2.48.0.rc2.279.g1de40edade-goog
> 
> 
---end quoted text---

Re: [PATCH 0/2 v5] add ioctl/sysfs to donate file-backed pages

[Jaegeuk Kim]

On 01/16, Christoph Hellwig wrote:
> Still NAC for sneaking in an almost undocumented MM feature into
> a file system ioctl.  Especially while a discussion on that is still
> ongoin.
> 
> And it's still bad that you don't even bother to Cc fsdevel on this,
> nor linux-api or in this case the mm list.

Well, I don't want to bother other groups for random APIs, unless I, myself, am
super confident this is feasible for generic API.
But, let me try to listen to other opinions.

> 
> On Thu, Jan 16, 2025 at 05:19:42PM +0000, Jaegeuk Kim wrote:
> > If users clearly know which file-backed pages to reclaim in system view, they
> > can use this ioctl() to register in advance and reclaim all at once later.
> > 
> > Change log from v4:
> >  - fix range handling
> > 
> > Change log from v3:
> >  - cover partial range
> > 
> > Change log from v2:
> >  - add more boundary checks
> >  - de-register the range, if len is zero
> > 
> > Jaegeuk Kim (1):
> >   f2fs: add a sysfs entry to request donate file-backed pages
> > 
> > Yi Sun (1):
> >   f2fs: Optimize f2fs_truncate_data_blocks_range()
> > 
> >  Documentation/ABI/testing/sysfs-fs-f2fs |  7 ++++++
> >  fs/f2fs/f2fs.h                          |  2 ++
> >  fs/f2fs/file.c                          | 29 +++++++++++++++++++++----
> >  fs/f2fs/shrinker.c                      | 27 +++++++++++++++++++++++
> >  fs/f2fs/sysfs.c                         |  8 +++++++
> >  5 files changed, 69 insertions(+), 4 deletions(-)
> > 
> > -- 
> > 2.48.0.rc2.279.g1de40edade-goog
> > 
> > 
> ---end quoted text---