f2fs: prevent checkpoint once any IO failure is detected

This patch enhances the checkpoint routine to cope with IO errors.

Basically f2fs detects IO errors from end_io_write, and the errors are able to
be occurred during one of data, node, and meta page writes.

In the previous code, when an IO error is occurred during writes, f2fs sets a
flag, CP_ERROR_FLAG, in the raw ckeckpoint buffer which will be written to disk.
Afterwards, write_checkpoint() will check the flag and remount f2fs as a
read-only (ro) mode.

However, even once f2fs is remounted as a ro mode, dirty checkpoint pages are
freely able to be written to disk by flusher or kswapd in background.
In such a case, after cold reboot, f2fs would restore the checkpoint data having
CP_ERROR_FLAG, resulting in disabling write_checkpoint and remounting f2fs as
a ro mode again.

Therefore, let's prevent any checkpoint page (meta) writes once an IO error is
occurred, and remount f2fs as a ro mode right away at that moment.

Reported-by: Oliver Winker <oliver@oli1170.net>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>

1 files changed, 9 insertions, 3 deletions

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 37fad04c8669..117ca2a46e39 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -387,10 +387,11 @@ static int sanity_check_raw_super(struct super_block *sb,
         return 0;
 }
 
-static int sanity_check_ckpt(struct f2fs_super_block *raw_super,
-                                struct f2fs_checkpoint *ckpt)
+static int sanity_check_ckpt(struct f2fs_sb_info *sbi)
 {
         unsigned int total, fsmeta;
+        struct f2fs_super_block *raw_super = F2FS_RAW_SUPER(sbi);
+        struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
 
         total = le32_to_cpu(raw_super->segment_count);
         fsmeta = le32_to_cpu(raw_super->segment_count_ckpt);
@@ -401,6 +402,11 @@ static int sanity_check_ckpt(struct f2fs_super_block *raw_super,
 
         if (fsmeta >= total)
                 return 1;
+
+        if (is_set_ckpt_flags(ckpt, CP_ERROR_FLAG)) {
+                f2fs_msg(sbi->sb, KERN_ERR, "A bug case: need to run fsck");
+                return 1;
+        }
         return 0;
 }
 
@@ -525,7 +531,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 
         /* sanity checking of checkpoint */
         err = -EINVAL;
-        if (sanity_check_ckpt(raw_super, sbi->ckpt)) {
+        if (sanity_check_ckpt(sbi)) {
                 f2fs_msg(sb, KERN_ERR, "Invalid F2FS checkpoint");
                 goto free_cp;
         }