f2fs: add sysfs nodes to get runtime compression stat

I've added new sysfs nodes to show runtime compression stat since mount.
compr_written_block - show the block count written after compression
compr_saved_block - show the saved block count with compression
compr_new_inode - show the count of inode newly enabled for compression

Signed-off-by: Daeho Jeong <daehojeong@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Documentation/ABI/testing/sysfs-fs-f2fs

@@ -414,3 +414,27 @@ What:		/sys/fs/f2fs/<disk>/ovp_segments
 Date:		March 2021
 Contact:	"Jaegeuk Kim" <jaegeuk@kernel.org>
 Description:	Shows the number of overprovision segments.
+
+What:		/sys/fs/f2fs/<disk>/compr_written_block
+Date:		March 2021
+Contact:	"Daeho Jeong" <daehojeong@google.com>
+Description:	Show the block count written after compression since mount. Note
+		that when the compressed blocks are deleted, this count doesn't
+		decrease. If you write "0" here, you can initialize
+		compr_written_block and compr_saved_block to "0".
+
+What:		/sys/fs/f2fs/<disk>/compr_saved_block
+Date:		March 2021
+Contact:	"Daeho Jeong" <daehojeong@google.com>
+Description:	Show the saved block count with compression since mount. Note
+		that when the compressed blocks are deleted, this count doesn't
+		decrease. If you write "0" here, you can initialize
+		compr_written_block and compr_saved_block to "0".
+
+What:		/sys/fs/f2fs/<disk>/compr_new_inode
+Date:		March 2021
+Contact:	"Daeho Jeong" <daehojeong@google.com>
+Description:	Show the count of inode newly enabled for compression since mount.
+		Note that when the compression is disabled for the files, this count
+		doesn't decrease. If you write "0" here, you can initialize
+		compr_new_inode to "0".

fs/f2fs/compress.c

@@ -1353,6 +1353,7 @@ unlock_continue:
 	if (fio.compr_blocks)
 		f2fs_i_compr_blocks_update(inode, fio.compr_blocks - 1, false);
 	f2fs_i_compr_blocks_update(inode, cc->nr_cpages, true);
+	add_compr_block_stat(inode, cc->nr_cpages);
 
 	set_inode_flag(cc->inode, FI_APPEND_WRITE);
 	if (cc->cluster_idx == 0)

fs/f2fs/f2fs.h

@@ -1628,6 +1628,11 @@ struct f2fs_sb_info {
 #ifdef CONFIG_F2FS_FS_COMPRESSION
 	struct kmem_cache *page_array_slab;	/* page array entry */
 	unsigned int page_array_slab_size;	/* default page array slab size */
+
+	/* For runtime compression statistics */
+	u64 compr_written_block;
+	u64 compr_saved_block;
+	u32 compr_new_inode;
 #endif
 };
 
@@ -3961,6 +3966,18 @@ int f2fs_init_page_array_cache(struct f2fs_sb_info *sbi);
 void f2fs_destroy_page_array_cache(struct f2fs_sb_info *sbi);
 int __init f2fs_init_compress_cache(void);
 void f2fs_destroy_compress_cache(void);
+#define inc_compr_inode_stat(inode)					\
+	do {								\
+		struct f2fs_sb_info *sbi = F2FS_I_SB(inode);		\
+		sbi->compr_new_inode++;					\
+	} while (0)
+#define add_compr_block_stat(inode, blocks)				\
+	do {								\
+		struct f2fs_sb_info *sbi = F2FS_I_SB(inode);		\
+		int diff = F2FS_I(inode)->i_cluster_size - blocks;	\
+		sbi->compr_written_block += blocks;			\
+		sbi->compr_saved_block += diff;				\
+	} while (0)
 #else
 static inline bool f2fs_is_compressed_page(struct page *page) { return false; }
 static inline bool f2fs_is_compress_backend_ready(struct inode *inode)
@@ -3989,6 +4006,7 @@ static inline int f2fs_init_page_array_cache(struct f2fs_sb_info *sbi) { return
 static inline void f2fs_destroy_page_array_cache(struct f2fs_sb_info *sbi) { }
 static inline int __init f2fs_init_compress_cache(void) { return 0; }
 static inline void f2fs_destroy_compress_cache(void) { }
+#define inc_compr_inode_stat(inode)		do { } while (0)
 #endif
 
 static inline void set_compress_context(struct inode *inode)
@@ -4012,6 +4030,7 @@ static inline void set_compress_context(struct inode *inode)
 	F2FS_I(inode)->i_flags |= F2FS_COMPR_FL;
 	set_inode_flag(inode, FI_COMPRESSED_FILE);
 	stat_inc_compr_inode(inode);
+	inc_compr_inode_stat(inode);
 	f2fs_mark_inode_dirty_sync(inode, true);
 }
 

fs/f2fs/sysfs.c

@@ -12,6 +12,7 @@
 #include <linux/seq_file.h>
 #include <linux/unicode.h>
 #include <linux/ioprio.h>
+#include <linux/sysfs.h>
 
 #include "f2fs.h"
 #include "segment.h"
@@ -289,6 +290,17 @@ static ssize_t f2fs_sbi_show(struct f2fs_attr *a,
 		return len;
 	}
 
+#ifdef CONFIG_F2FS_FS_COMPRESSION
+	if (!strcmp(a->attr.name, "compr_written_block"))
+		return sysfs_emit(buf, "%llu\n", sbi->compr_written_block);
+
+	if (!strcmp(a->attr.name, "compr_saved_block"))
+		return sysfs_emit(buf, "%llu\n", sbi->compr_saved_block);
+
+	if (!strcmp(a->attr.name, "compr_new_inode"))
+		return sysfs_emit(buf, "%u\n", sbi->compr_new_inode);
+#endif
+
 	ui = (unsigned int *)(ptr + a->offset);
 
 	return sprintf(buf, "%u\n", *ui);
@@ -465,6 +477,24 @@ out:
 		return count;
 	}
 
+#ifdef CONFIG_F2FS_FS_COMPRESSION
+	if (!strcmp(a->attr.name, "compr_written_block") ||
+		!strcmp(a->attr.name, "compr_saved_block")) {
+		if (t != 0)
+			return -EINVAL;
+		sbi->compr_written_block = 0;
+		sbi->compr_saved_block = 0;
+		return count;
+	}
+
+	if (!strcmp(a->attr.name, "compr_new_inode")) {
+		if (t != 0)
+			return -EINVAL;
+		sbi->compr_new_inode = 0;
+		return count;
+	}
+#endif
+
 	*ui = (unsigned int)t;
 
 	return count;
@@ -676,6 +706,9 @@ F2FS_FEATURE_RO_ATTR(sb_checksum, FEAT_SB_CHECKSUM);
 F2FS_FEATURE_RO_ATTR(casefold, FEAT_CASEFOLD);
 #ifdef CONFIG_F2FS_FS_COMPRESSION
 F2FS_FEATURE_RO_ATTR(compression, FEAT_COMPRESSION);
+F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, compr_written_block, compr_written_block);
+F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, compr_saved_block, compr_saved_block);
+F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, compr_new_inode, compr_new_inode);
 #endif
 
 #define ATTR_LIST(name) (&f2fs_attr_##name.attr)
@@ -739,6 +772,11 @@ static struct attribute *f2fs_attrs[] = {
 	ATTR_LIST(moved_blocks_foreground),
 	ATTR_LIST(moved_blocks_background),
 	ATTR_LIST(avg_vblocks),
+#endif
+#ifdef CONFIG_F2FS_FS_COMPRESSION
+	ATTR_LIST(compr_written_block),
+	ATTR_LIST(compr_saved_block),
+	ATTR_LIST(compr_new_inode),
 #endif
 	NULL,
 };