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>
 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".
 
        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)
 
 #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
 };
 
 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)
 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)
        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);
 }
 
 
 #include <linux/seq_file.h>
 #include <linux/unicode.h>
 #include <linux/ioprio.h>
+#include <linux/sysfs.h>
 
 #include "f2fs.h"
 #include "segment.h"
                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);
                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;
 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)
        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,
 };