Previously, we used cp_version only to detect recoverable dnodes.
In order to avoid same garbage cp_version, we needed to truncate the next
dnode during checkpoint, resulting in additional discard or data write.
If we can distinguish this by using crc in addition to cp_version, we can
remove this overhead.

There is backward compatibility concern where it changes node_footer layout.
But, it only affects the direct nodes written after the last checkpoint.
We simply expect that user would change kernel versions back and forth after
stable checkpoint.

Signed-off-by: Jaegeuk Kim <jaeg...@kernel.org>
---
 fs/f2fs/checkpoint.c | 18 -------------
 fs/f2fs/f2fs.h       |  1 -
 fs/f2fs/node.h       | 73 ++++++++++++++++++++++++++++++++--------------------
 fs/f2fs/recovery.c   | 36 +++++---------------------
 fs/f2fs/segment.c    | 22 ----------------
 fs/f2fs/super.c      |  5 +++-
 6 files changed, 55 insertions(+), 100 deletions(-)

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index df56a43..6ecc5b8 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -992,7 +992,6 @@ static void wait_on_all_pages_writeback(struct f2fs_sb_info 
*sbi)
 static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 {
        struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
-       struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_WARM_NODE);
        struct f2fs_nm_info *nm_i = NM_I(sbi);
        unsigned long orphan_num = sbi->im[ORPHAN_INO].ino_num;
        nid_t last_nid = nm_i->next_scan_nid;
@@ -1001,19 +1000,10 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, 
struct cp_control *cpc)
        __u32 crc32 = 0;
        int i;
        int cp_payload_blks = __cp_payload(sbi);
-       block_t discard_blk = NEXT_FREE_BLKADDR(sbi, curseg);
-       bool invalidate = false;
        struct super_block *sb = sbi->sb;
        struct curseg_info *seg_i = CURSEG_I(sbi, CURSEG_HOT_NODE);
        u64 kbytes_written;
 
-       /*
-        * This avoids to conduct wrong roll-forward operations and uses
-        * metapages, so should be called prior to sync_meta_pages below.
-        */
-       if (!test_opt(sbi, LFS) && discard_next_dnode(sbi, discard_blk))
-               invalidate = true;
-
        /* Flush all the NAT/SIT pages */
        while (get_pages(sbi, F2FS_DIRTY_META)) {
                sync_meta_pages(sbi, META, LONG_MAX);
@@ -1154,14 +1144,6 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, 
struct cp_control *cpc)
        /* wait for previous submitted meta pages writeback */
        wait_on_all_pages_writeback(sbi);
 
-       /*
-        * invalidate meta page which is used temporarily for zeroing out
-        * block at the end of warm node chain.
-        */
-       if (invalidate)
-               invalidate_mapping_pages(META_MAPPING(sbi), discard_blk,
-                                                               discard_blk);
-
        release_ino_entry(sbi, false);
 
        if (unlikely(f2fs_cp_error(sbi)))
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 132756c..a472191 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -2065,7 +2065,6 @@ void refresh_sit_entry(struct f2fs_sb_info *, block_t, 
block_t);
 void f2fs_wait_all_discard_bio(struct f2fs_sb_info *);
 void clear_prefree_segments(struct f2fs_sb_info *, struct cp_control *);
 void release_discard_addrs(struct f2fs_sb_info *);
-bool discard_next_dnode(struct f2fs_sb_info *, block_t);
 int npages_for_summary_flush(struct f2fs_sb_info *, bool);
 void allocate_new_segments(struct f2fs_sb_info *);
 int f2fs_trim_fs(struct f2fs_sb_info *, struct fstrim_range *);
diff --git a/fs/f2fs/node.h b/fs/f2fs/node.h
index fc76845..e8114f9 100644
--- a/fs/f2fs/node.h
+++ b/fs/f2fs/node.h
@@ -229,6 +229,37 @@ static inline void set_to_next_nat(struct f2fs_nm_info 
*nm_i, nid_t start_nid)
        f2fs_change_bit(block_off, nm_i->nat_bitmap);
 }
 
+static inline nid_t ino_of_node(struct page *node_page)
+{
+       struct f2fs_node *rn = F2FS_NODE(node_page);
+       return le32_to_cpu(rn->footer.ino);
+}
+
+static inline nid_t nid_of_node(struct page *node_page)
+{
+       struct f2fs_node *rn = F2FS_NODE(node_page);
+       return le32_to_cpu(rn->footer.nid);
+}
+
+static inline unsigned int ofs_of_node(struct page *node_page)
+{
+       struct f2fs_node *rn = F2FS_NODE(node_page);
+       unsigned flag = le32_to_cpu(rn->footer.flag);
+       return flag >> OFFSET_BIT_SHIFT;
+}
+
+static inline __u64 cpver_of_node(struct page *node_page)
+{
+       struct f2fs_node *rn = F2FS_NODE(node_page);
+       return le64_to_cpu(rn->footer.cp_ver);
+}
+
+static inline block_t next_blkaddr_of_node(struct page *node_page)
+{
+       struct f2fs_node *rn = F2FS_NODE(node_page);
+       return le32_to_cpu(rn->footer.next_blkaddr);
+}
+
 static inline void fill_node_footer(struct page *page, nid_t nid,
                                nid_t ino, unsigned int ofs, bool reset)
 {
@@ -259,40 +290,26 @@ static inline void fill_node_footer_blkaddr(struct page 
*page, block_t blkaddr)
 {
        struct f2fs_checkpoint *ckpt = F2FS_CKPT(F2FS_P_SB(page));
        struct f2fs_node *rn = F2FS_NODE(page);
+       size_t crc_offset = le32_to_cpu(ckpt->checksum_offset);
+       __u64 cp_ver = le64_to_cpu(ckpt->checkpoint_ver);
+       __u64 crc;
 
-       rn->footer.cp_ver = ckpt->checkpoint_ver;
+       crc = le32_to_cpu(*((__le32 *)((unsigned char *)ckpt + crc_offset)));
+       cp_ver |= (crc << 32);
+       rn->footer.cp_ver = cpu_to_le64(cp_ver);
        rn->footer.next_blkaddr = cpu_to_le32(blkaddr);
 }
 
-static inline nid_t ino_of_node(struct page *node_page)
-{
-       struct f2fs_node *rn = F2FS_NODE(node_page);
-       return le32_to_cpu(rn->footer.ino);
-}
-
-static inline nid_t nid_of_node(struct page *node_page)
-{
-       struct f2fs_node *rn = F2FS_NODE(node_page);
-       return le32_to_cpu(rn->footer.nid);
-}
-
-static inline unsigned int ofs_of_node(struct page *node_page)
-{
-       struct f2fs_node *rn = F2FS_NODE(node_page);
-       unsigned flag = le32_to_cpu(rn->footer.flag);
-       return flag >> OFFSET_BIT_SHIFT;
-}
-
-static inline unsigned long long cpver_of_node(struct page *node_page)
+static inline bool is_recoverable_dnode(struct page *page)
 {
-       struct f2fs_node *rn = F2FS_NODE(node_page);
-       return le64_to_cpu(rn->footer.cp_ver);
-}
+       struct f2fs_checkpoint *ckpt = F2FS_CKPT(F2FS_P_SB(page));
+       size_t crc_offset = le32_to_cpu(ckpt->checksum_offset);
+       __u64 cp_ver = cur_cp_version(ckpt);
+       __u64 crc;
 
-static inline block_t next_blkaddr_of_node(struct page *node_page)
-{
-       struct f2fs_node *rn = F2FS_NODE(node_page);
-       return le32_to_cpu(rn->footer.next_blkaddr);
+       crc = le32_to_cpu(*((__le32 *)((unsigned char *)ckpt + crc_offset)));
+       cp_ver |= (crc << 32);
+       return cpu_to_le64(cp_ver) == cpver_of_node(page);
 }
 
 /*
diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
index ad748e5..2b8a56d 100644
--- a/fs/f2fs/recovery.c
+++ b/fs/f2fs/recovery.c
@@ -224,7 +224,6 @@ static bool is_same_inode(struct inode *inode, struct page 
*ipage)
 
 static int find_fsync_dnodes(struct f2fs_sb_info *sbi, struct list_head *head)
 {
-       unsigned long long cp_ver = cur_cp_version(F2FS_CKPT(sbi));
        struct curseg_info *curseg;
        struct page *page = NULL;
        block_t blkaddr;
@@ -242,7 +241,7 @@ static int find_fsync_dnodes(struct f2fs_sb_info *sbi, 
struct list_head *head)
 
                page = get_tmp_page(sbi, blkaddr);
 
-               if (cp_ver != cpver_of_node(page))
+               if (!is_recoverable_dnode(page))
                        break;
 
                if (!is_fsync_dnode(page))
@@ -516,7 +515,6 @@ out:
 static int recover_data(struct f2fs_sb_info *sbi, struct list_head *inode_list,
                                                struct list_head *dir_list)
 {
-       unsigned long long cp_ver = cur_cp_version(F2FS_CKPT(sbi));
        struct curseg_info *curseg;
        struct page *page = NULL;
        int err = 0;
@@ -536,7 +534,7 @@ static int recover_data(struct f2fs_sb_info *sbi, struct 
list_head *inode_list,
 
                page = get_tmp_page(sbi, blkaddr);
 
-               if (cp_ver != cpver_of_node(page)) {
+               if (!is_recoverable_dnode(page)) {
                        f2fs_put_page(page, 1);
                        break;
                }
@@ -628,37 +626,15 @@ out:
        }
 
        clear_sbi_flag(sbi, SBI_POR_DOING);
-       if (err) {
-               bool invalidate = false;
-
-               if (test_opt(sbi, LFS)) {
-                       update_meta_page(sbi, NULL, blkaddr);
-                       invalidate = true;
-               } else if (discard_next_dnode(sbi, blkaddr)) {
-                       invalidate = true;
-               }
-
-               f2fs_wait_all_discard_bio(sbi);
-
-               /* Flush all the NAT/SIT pages */
-               while (get_pages(sbi, F2FS_DIRTY_META))
-                       sync_meta_pages(sbi, META, LONG_MAX);
-
-               /* invalidate temporary meta page */
-               if (invalidate)
-                       invalidate_mapping_pages(META_MAPPING(sbi),
-                                                       blkaddr, blkaddr);
-
+       if (err)
                set_ckpt_flags(sbi->ckpt, CP_ERROR_FLAG);
-               mutex_unlock(&sbi->cp_mutex);
-       } else if (need_writecp) {
+       mutex_unlock(&sbi->cp_mutex);
+
+       if (!err && need_writecp) {
                struct cp_control cpc = {
                        .reason = CP_RECOVERY,
                };
-               mutex_unlock(&sbi->cp_mutex);
                err = write_checkpoint(sbi, &cpc);
-       } else {
-               mutex_unlock(&sbi->cp_mutex);
        }
 
        destroy_fsync_dnodes(&dir_list);
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 101b58f..4376326 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -669,28 +669,6 @@ static int f2fs_issue_discard(struct f2fs_sb_info *sbi,
        return __f2fs_issue_discard_async(sbi, start, len, GFP_NOFS, 0);
 }
 
-bool discard_next_dnode(struct f2fs_sb_info *sbi, block_t blkaddr)
-{
-       int err = -EOPNOTSUPP;
-
-       if (test_opt(sbi, DISCARD)) {
-               struct seg_entry *se = get_seg_entry(sbi,
-                               GET_SEGNO(sbi, blkaddr));
-               unsigned int offset = GET_BLKOFF_FROM_SEG0(sbi, blkaddr);
-
-               if (f2fs_test_bit(offset, se->discard_map))
-                       return false;
-
-               err = f2fs_issue_discard(sbi, blkaddr, 1);
-       }
-
-       if (err) {
-               update_meta_page(sbi, NULL, blkaddr);
-               return true;
-       }
-       return false;
-}
-
 static void __add_discard_entry(struct f2fs_sb_info *sbi,
                struct cp_control *cpc, struct seg_entry *se,
                unsigned int start, unsigned int end)
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 29e3cf4..7fda940 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1812,6 +1812,9 @@ try_onemore:
        if (err)
                goto free_proc;
 
+       if (!retry)
+               goto skip_recovery;
+
        /* recover fsynced data */
        if (!test_opt(sbi, DISABLE_ROLL_FORWARD)) {
                /*
@@ -1844,7 +1847,7 @@ try_onemore:
                        goto free_kobj;
                }
        }
-
+skip_recovery:
        /* recover_fsync_data() cleared this already */
        clear_sbi_flag(sbi, SBI_POR_DOING);
 
-- 
2.8.3


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