ext4: handle errors on ext4_commit_super

PATCH In review Jaegeuk Kim 3 participants 7 messages Mar 30, 2018 – May 14, 2018 ext4 file system

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Jaegeuk Kim

author

2018-03-30 01:44 UTC #0 lore raw

PATCH 1/1 ext4: handle errors on ext4_commit_super

From: Jaegeuk Kim <[email protected]>

When remounting ext4 from ro to rw, currently it allows its transition, even if ext4_commit_super() returns EIO. Even worse thing is, after that, fs/buffer complains buffer dirty bits like:

 Call trace:
 [<ffffff9750c259dc>] mark_buffer_dirty+0x184/0x1a4
 [<ffffff9750cb398c>] __ext4_handle_dirty_super+0x4c/0xfc
 [<ffffff9750c7a9fc>] ext4_file_open+0x154/0x1c0
 [<ffffff9750bea51c>] do_dentry_open+0x114/0x2d0
 [<ffffff9750bea75c>] vfs_open+0x5c/0x94
 [<ffffff9750bf879c>] path_openat+0x668/0xfe8
 [<ffffff9750bf8088>] do_filp_open+0x74/0x120
 [<ffffff9750beac98>] do_sys_open+0x148/0x254
 [<ffffff9750beade0>] SyS_openat+0x10/0x18
 [<ffffff9750a83ab0>] el0_svc_naked+0x24/0x28
 EXT4-fs (dm-1): previous I/O error to superblock detected
 Buffer I/O error on dev dm-1, logical block 0, lost sync page write
 EXT4-fs (dm-1): re-mounted. Opts: (null)
 Buffer I/O error on dev dm-1, logical block 80, lost async page write

Cc "Theodore Ts'o" <[email protected]>

Cc Andreas Dilger <[email protected]>

Cc [email protected]

Cc Jaegeuk Kim <[email protected]>

Signed-off-by Jaegeuk Kim <[email protected]>

---
 fs/ext4/super.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

fs/ext4/super.c +13 -8

index 39bf464c35f1..b268bfea879c 100644
@@ -2151,7 +2151,7 @@ static int ext4_setup_super(struct super_block *sb, struct ext4_super_block *es,
 	if (sbi->s_journal)
 		ext4_set_feature_journal_needs_recovery(sb);
 
-	ext4_commit_super(sb, 1);
+	res = ext4_commit_super(sb, 1);
 done:
 	if (test_opt(sb, DEBUG))
 		printk(KERN_INFO "[EXT4 FS bs=%lu, gc=%u, "

@@ -4739,11 +4739,10 @@ static int ext4_commit_super(struct super_block *sb, int sync)
 		unlock_buffer(sbh);
 		error = __sync_dirty_buffer(sbh,
 			REQ_SYNC | (test_opt(sb, BARRIER) ? REQ_FUA : 0));
-		if (error)
+		if (error && !buffer_write_io_error(sbh))
 			return error;
 
-		error = buffer_write_io_error(sbh);
-		if (error) {
+		if (buffer_write_io_error(sbh)) {
 			ext4_msg(sb, KERN_ERR, "I/O error while writing "
 			       "superblock");
 			clear_buffer_write_io_error(sbh);

@@ -5144,8 +5143,12 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 			if (sbi->s_journal)
 				ext4_clear_journal_err(sb, es);
 			sbi->s_mount_state = le16_to_cpu(es->s_state);
-			if (!ext4_setup_super(sb, es, 0))
-				sb->s_flags &= ~SB_RDONLY;
+
+			err = ext4_setup_super(sb, es, 0);
+			if (err)
+				goto restore_opts;
+
+			sb->s_flags &= ~SB_RDONLY;
 			if (ext4_has_feature_mmp(sb))
 				if (ext4_multi_mount_protect(sb,
 						le64_to_cpu(es->s_mmp_block))) {

@@ -5169,8 +5172,10 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 	}
 
 	ext4_setup_system_zone(sb);
-	if (sbi->s_journal == NULL && !(old_sb_flags & SB_RDONLY))
-		ext4_commit_super(sb, 1);
+	if (sbi->s_journal == NULL && !(old_sb_flags & SB_RDONLY)) {
+		err = ext4_commit_super(sb, 1);
+		goto restore_opts;
+	}
 
 #ifdef CONFIG_QUOTA
 	/* Release old quota file names */

Signature · 1 line

2.15.0.531.g2ccb3012c9-goog

Jan Kara

reviewer

2018-04-19 15:18 UTC #1 lore raw

Quoted 22 lines · Jaegeuk Kim

From: Jaegeuk Kim <[email protected]>

When remounting ext4 from ro to rw, currently it allows its transition, even if ext4_commit_super() returns EIO. Even worse thing is, after that, fs/buffer complains buffer dirty bits like:

 Call trace:
 [<ffffff9750c259dc>] mark_buffer_dirty+0x184/0x1a4
 [<ffffff9750cb398c>] __ext4_handle_dirty_super+0x4c/0xfc
 [<ffffff9750c7a9fc>] ext4_file_open+0x154/0x1c0
 [<ffffff9750bea51c>] do_dentry_open+0x114/0x2d0
 [<ffffff9750bea75c>] vfs_open+0x5c/0x94
 [<ffffff9750bf879c>] path_openat+0x668/0xfe8
 [<ffffff9750bf8088>] do_filp_open+0x74/0x120
 [<ffffff9750beac98>] do_sys_open+0x148/0x254
 [<ffffff9750beade0>] SyS_openat+0x10/0x18
 [<ffffff9750a83ab0>] el0_svc_naked+0x24/0x28
 EXT4-fs (dm-1): previous I/O error to superblock detected
 Buffer I/O error on dev dm-1, logical block 0, lost sync page write
 EXT4-fs (dm-1): re-mounted. Opts: (null)
 Buffer I/O error on dev dm-1, logical block 80, lost async page write

Quoted 8 lines

Cc "Theodore Ts'o" <[email protected]>
Cc Andreas Dilger <[email protected]>
Cc [email protected]
Cc Jaegeuk Kim <[email protected]>
Signed-off-by Jaegeuk Kim <[email protected]>
---
 fs/ext4/super.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

Thanks for the patch. Some comments below.

Quoted 6 lines

fs/ext4/super.c +0 -0
index 39bf464c35f1..b268bfea879c 100644

fs/ext4/super.c static int ext4_setup_super(struct super_block *sb, struct ext4_super_block *es, · line 2157

Quoted 8 lines

fs/ext4/super.c +1 -1

@@ -2151,7 +2151,7 @@ static int ext4_setup_super(struct super_block *sb, struct ext4_super_block *es,
 	if (sbi->s_journal)
 		ext4_set_feature_journal_needs_recovery(sb);
 
-	ext4_commit_super(sb, 1);
+	res = ext4_commit_super(sb, 1);
 done:
 	if (test_opt(sb, DEBUG))
 		printk(KERN_INFO "[EXT4 FS bs=%lu, gc=%u, "

So return value of ext4_setup_super() looks a bit strange and it seems it currently returns 0 or SB_RDONLY. So I think you first need to clean this up before making ext4_setup_super() return error code (as your patch could make ext4_fill_super() return SB_RDONLY under some circumstances).

Quoted 4 lines

fs/ext4/super.c +0 -0

@@ -4739,11 +4739,10 @@ static int ext4_commit_super(struct super_block *sb, int sync)
 		unlock_buffer(sbh);
 		error = __sync_dirty_buffer(sbh,
 			REQ_SYNC | (test_opt(sb, BARRIER) ? REQ_FUA : 0));

fs/ext4/super.c static int ext4_commit_super(struct super_block *sb, int sync) · line 4748

Quoted 10 lines

fs/ext4/super.c +2 -3

-		if (error)
+		if (error && !buffer_write_io_error(sbh))
 			return error;
 
-		error = buffer_write_io_error(sbh);
-		if (error) {
+		if (buffer_write_io_error(sbh)) {
 			ext4_msg(sb, KERN_ERR, "I/O error while writing "
 			       "superblock");
 			clear_buffer_write_io_error(sbh);

I'd rather rewrite this as:

		if (buffer_write_io_error(sbh)) {
			do stuff as now
		}
		if (error)
			return error;

								Honza

Signature · 2 lines

Jan Kara <[email protected]>
SUSE Labs, CR

Jaegeuk Kim

author

2018-04-19 15:58 UTC #2 lore raw

Hi Jan,

Thank you for the review.

Quoted 43 lines · Jan Kara

Quoted 22 lines · Jaegeuk Kim
From: Jaegeuk Kim <[email protected]>
When remounting ext4 from ro to rw, currently it allows its transition, even if ext4_commit_super() returns EIO. Even worse thing is, after that, fs/buffer complains buffer dirty bits like:
 Call trace:
 [<ffffff9750c259dc>] mark_buffer_dirty+0x184/0x1a4
 [<ffffff9750cb398c>] __ext4_handle_dirty_super+0x4c/0xfc
 [<ffffff9750c7a9fc>] ext4_file_open+0x154/0x1c0
 [<ffffff9750bea51c>] do_dentry_open+0x114/0x2d0
 [<ffffff9750bea75c>] vfs_open+0x5c/0x94
 [<ffffff9750bf879c>] path_openat+0x668/0xfe8
 [<ffffff9750bf8088>] do_filp_open+0x74/0x120
 [<ffffff9750beac98>] do_sys_open+0x148/0x254
 [<ffffff9750beade0>] SyS_openat+0x10/0x18
 [<ffffff9750a83ab0>] el0_svc_naked+0x24/0x28
 EXT4-fs (dm-1): previous I/O error to superblock detected
 Buffer I/O error on dev dm-1, logical block 0, lost sync page write
 EXT4-fs (dm-1): re-mounted. Opts: (null)
 Buffer I/O error on dev dm-1, logical block 80, lost async page write
Quoted 8 lines
Cc "Theodore Ts'o" <[email protected]>
Cc Andreas Dilger <[email protected]>
Cc [email protected]
Cc Jaegeuk Kim <[email protected]>
Signed-off-by Jaegeuk Kim <[email protected]>
---
 fs/ext4/super.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)
Thanks for the patch. Some comments below.
Quoted 9 lines
fs/ext4/super.c +0 -0
index 39bf464c35f1..b268bfea879c 100644
@@ -2151,7 +2151,7 @@ static int ext4_setup_super(struct super_block *sb, struct ext4_super_block *es,
 	if (sbi->s_journal)
 		ext4_set_feature_journal_needs_recovery(sb);
 

Quoted 8 lines

fs/ext4/super.c static int ext4_setup_super(struct super_block *sb, struct ext4_super_block *es, · line 2157
Quoted 5 lines
fs/ext4/super.c +1 -1
-	ext4_commit_super(sb, 1);
+	res = ext4_commit_super(sb, 1);
 done:
 	if (test_opt(sb, DEBUG))
 		printk(KERN_INFO "[EXT4 FS bs=%lu, gc=%u, "
So return value of ext4_setup_super() looks a bit strange and it seems it currently returns 0 or SB_RDONLY. So I think you first need to clean this

Indeed. I'll update it in v2.

Quoted 2 lines

up before making ext4_setup_super() return error code (as your patch could make ext4_fill_super() return SB_RDONLY under some circumstances).

Interestingly, it only affects ext4_remount() only. :P

Quoted 17 lines

Quoted 5 lines

fs/ext4/super.c +0 -0

@@ -4739,11 +4739,10 @@ static int ext4_commit_super(struct super_block *sb, int sync)
 		unlock_buffer(sbh);
 		error = __sync_dirty_buffer(sbh,
 			REQ_SYNC | (test_opt(sb, BARRIER) ? REQ_FUA : 0));

fs/ext4/super.c static int ext4_commit_super(struct super_block *sb, int sync) · line 4748

Quoted 10 lines

fs/ext4/super.c +2 -3

-		if (error)
+		if (error && !buffer_write_io_error(sbh))
 			return error;
 
-		error = buffer_write_io_error(sbh);
-		if (error) {
+		if (buffer_write_io_error(sbh)) {
 			ext4_msg(sb, KERN_ERR, "I/O error while writing "
 			       "superblock");
 			clear_buffer_write_io_error(sbh);

I'd rather rewrite this as:

Quoted 5 lines

		if (buffer_write_io_error(sbh)) {
			do stuff as now
		}
		if (error)
			return error;

Got it.

Thanks,

Quoted 5 lines

Honza
Signature · 2 lines
Jan Kara <[email protected]>
SUSE Labs, CR

Jaegeuk Kim

author

2018-04-19 15:59 UTC #3 lore raw

In reply to Jaegeuk Kim

When remounting ext4 from ro to rw, currently it allows its transition, even if ext4_commit_super() returns EIO. Even worse thing is, after that, fs/buffer complains buffer dirty bits like:

 Call trace:
 [<ffffff9750c259dc>] mark_buffer_dirty+0x184/0x1a4
 [<ffffff9750cb398c>] __ext4_handle_dirty_super+0x4c/0xfc
 [<ffffff9750c7a9fc>] ext4_file_open+0x154/0x1c0
 [<ffffff9750bea51c>] do_dentry_open+0x114/0x2d0
 [<ffffff9750bea75c>] vfs_open+0x5c/0x94
 [<ffffff9750bf879c>] path_openat+0x668/0xfe8
 [<ffffff9750bf8088>] do_filp_open+0x74/0x120
 [<ffffff9750beac98>] do_sys_open+0x148/0x254
 [<ffffff9750beade0>] SyS_openat+0x10/0x18
 [<ffffff9750a83ab0>] el0_svc_naked+0x24/0x28
 EXT4-fs (dm-1): previous I/O error to superblock detected
 Buffer I/O error on dev dm-1, logical block 0, lost sync page write
 EXT4-fs (dm-1): re-mounted. Opts: (null)
 Buffer I/O error on dev dm-1, logical block 80, lost async page write

Cc "Theodore Ts'o" <[email protected]>

Cc Andreas Dilger <[email protected]>

Cc [email protected]

Cc Jaegeuk Kim <[email protected]>

Signed-off-by Jaegeuk Kim <[email protected]>

---

Change log from v1:
- modify return value of ext4_setup_super
- change the error handling order in ext4_commit_super

 fs/ext4/super.c | 28 +++++++++++++++-------------
 1 file changed, 15 insertions(+), 13 deletions(-)

fs/ext4/super.c +15 ~~-13~~

index 185f7e61f4cf..af4d373aa3ed 100644
@@ -2116,12 +2116,12 @@ static int ext4_setup_super(struct super_block *sb, struct ext4_super_block *es,
 			    int read_only)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
-	int res = 0;
+	int err = 0;
 
 	if (le32_to_cpu(es->s_rev_level) > EXT4_MAX_SUPP_REV) {
 		ext4_msg(sb, KERN_ERR, "revision level too high, "
 			 "forcing read-only mode");
-		res = SB_RDONLY;
+		err = -EROFS;
 	}
 	if (read_only)
 		goto done;

@@ -2154,7 +2154,7 @@ static int ext4_setup_super(struct super_block *sb, struct ext4_super_block *es,
 	if (sbi->s_journal)
 		ext4_set_feature_journal_needs_recovery(sb);
 
-	ext4_commit_super(sb, 1);
+	err = ext4_commit_super(sb, 1);
 done:
 	if (test_opt(sb, DEBUG))
 		printk(KERN_INFO "[EXT4 FS bs=%lu, gc=%u, "

@@ -2166,7 +2166,7 @@ static int ext4_setup_super(struct super_block *sb, struct ext4_super_block *es,
 			sbi->s_mount_opt, sbi->s_mount_opt2);
 
 	cleancache_init_fs(sb);
-	return res;
+	return err;
 }
 
 int ext4_alloc_flex_bg_array(struct super_block *sb, ext4_group_t ngroup)

@@ -4760,11 +4760,7 @@ static int ext4_commit_super(struct super_block *sb, int sync)
 		unlock_buffer(sbh);
 		error = __sync_dirty_buffer(sbh,
 			REQ_SYNC | (test_opt(sb, BARRIER) ? REQ_FUA : 0));
-		if (error)
-			return error;
-
-		error = buffer_write_io_error(sbh);
-		if (error) {
+		if (buffer_write_io_error(sbh)) {
 			ext4_msg(sb, KERN_ERR, "I/O error while writing "
 			       "superblock");
 			clear_buffer_write_io_error(sbh);

@@ -5165,8 +5161,12 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 			if (sbi->s_journal)
 				ext4_clear_journal_err(sb, es);
 			sbi->s_mount_state = le16_to_cpu(es->s_state);
-			if (!ext4_setup_super(sb, es, 0))
-				sb->s_flags &= ~SB_RDONLY;
+
+			err = ext4_setup_super(sb, es, 0);
+			if (err)
+				goto restore_opts;
+
+			sb->s_flags &= ~SB_RDONLY;
 			if (ext4_has_feature_mmp(sb))
 				if (ext4_multi_mount_protect(sb,
 						le64_to_cpu(es->s_mmp_block))) {

@@ -5190,8 +5190,10 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 	}
 
 	ext4_setup_system_zone(sb);
-	if (sbi->s_journal == NULL && !(old_sb_flags & SB_RDONLY))
-		ext4_commit_super(sb, 1);
+	if (sbi->s_journal == NULL && !(old_sb_flags & SB_RDONLY)) {
+		err = ext4_commit_super(sb, 1);
+		goto restore_opts;
+	}
 
 #ifdef CONFIG_QUOTA
 	/* Release old quota file names */

Signature · 1 line

2.17.0.484.g0c8726318c-goog

Jan Kara

reviewer

2018-04-21 13:12 UTC #4 lore raw

Quoted 20 lines · Jaegeuk Kim

When remounting ext4 from ro to rw, currently it allows its transition, even if ext4_commit_super() returns EIO. Even worse thing is, after that, fs/buffer complains buffer dirty bits like:

 Call trace:
 [<ffffff9750c259dc>] mark_buffer_dirty+0x184/0x1a4
 [<ffffff9750cb398c>] __ext4_handle_dirty_super+0x4c/0xfc
 [<ffffff9750c7a9fc>] ext4_file_open+0x154/0x1c0
 [<ffffff9750bea51c>] do_dentry_open+0x114/0x2d0
 [<ffffff9750bea75c>] vfs_open+0x5c/0x94
 [<ffffff9750bf879c>] path_openat+0x668/0xfe8
 [<ffffff9750bf8088>] do_filp_open+0x74/0x120
 [<ffffff9750beac98>] do_sys_open+0x148/0x254
 [<ffffff9750beade0>] SyS_openat+0x10/0x18
 [<ffffff9750a83ab0>] el0_svc_naked+0x24/0x28
 EXT4-fs (dm-1): previous I/O error to superblock detected
 Buffer I/O error on dev dm-1, logical block 0, lost sync page write
 EXT4-fs (dm-1): re-mounted. Opts: (null)
 Buffer I/O error on dev dm-1, logical block 80, lost async page write

Quoted 5 lines

Cc "Theodore Ts'o" <[email protected]>
Cc Andreas Dilger <[email protected]>
Cc [email protected]
Cc Jaegeuk Kim <[email protected]>
Signed-off-by Jaegeuk Kim <[email protected]>

Looks mostly good. Just:

fs/ext4/super.c static int ext4_remount(struct super_block *sb, int *flags, char *data) · line 5196

Quoted 10 lines

fs/ext4/super.c +4 -2

@@ -5190,8 +5190,10 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 	}
 
 	ext4_setup_system_zone(sb);
-	if (sbi->s_journal == NULL && !(old_sb_flags & SB_RDONLY))
-		ext4_commit_super(sb, 1);
+	if (sbi->s_journal == NULL && !(old_sb_flags & SB_RDONLY)) {
+		err = ext4_commit_super(sb, 1);
+		goto restore_opts;
+	}

Why is goto restore_opts unconditional here?

Honza

Signature · 2 lines

Jan Kara <[email protected]>
SUSE Labs, CR

Jaegeuk Kim

author

2018-04-23 14:46 UTC #5 lore raw

In reply to Jaegeuk Kim

When remounting ext4 from ro to rw, currently it allows its transition, even if ext4_commit_super() returns EIO. Even worse thing is, after that, fs/buffer complains buffer dirty bits like:

 Call trace:
 [<ffffff9750c259dc>] mark_buffer_dirty+0x184/0x1a4
 [<ffffff9750cb398c>] __ext4_handle_dirty_super+0x4c/0xfc
 [<ffffff9750c7a9fc>] ext4_file_open+0x154/0x1c0
 [<ffffff9750bea51c>] do_dentry_open+0x114/0x2d0
 [<ffffff9750bea75c>] vfs_open+0x5c/0x94
 [<ffffff9750bf879c>] path_openat+0x668/0xfe8
 [<ffffff9750bf8088>] do_filp_open+0x74/0x120
 [<ffffff9750beac98>] do_sys_open+0x148/0x254
 [<ffffff9750beade0>] SyS_openat+0x10/0x18
 [<ffffff9750a83ab0>] el0_svc_naked+0x24/0x28
 EXT4-fs (dm-1): previous I/O error to superblock detected
 Buffer I/O error on dev dm-1, logical block 0, lost sync page write
 EXT4-fs (dm-1): re-mounted. Opts: (null)
 Buffer I/O error on dev dm-1, logical block 80, lost async page write

Cc "Theodore Ts'o" <[email protected]>

Cc Andreas Dilger <[email protected]>

Cc [email protected]

Cc Jaegeuk Kim <[email protected]>

Signed-off-by Jaegeuk Kim <[email protected]>

---

Change log from v2:
- fix missing goto condition

 fs/ext4/super.c | 29 ++++++++++++++++-------------
 1 file changed, 16 insertions(+), 13 deletions(-)

fs/ext4/super.c +16 ~~-13~~

index 185f7e61f4cf..32cf16c33cba 100644
@@ -2116,12 +2116,12 @@ static int ext4_setup_super(struct super_block *sb, struct ext4_super_block *es,
 			    int read_only)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
-	int res = 0;
+	int err = 0;
 
 	if (le32_to_cpu(es->s_rev_level) > EXT4_MAX_SUPP_REV) {
 		ext4_msg(sb, KERN_ERR, "revision level too high, "
 			 "forcing read-only mode");
-		res = SB_RDONLY;
+		err = -EROFS;
 	}
 	if (read_only)
 		goto done;

@@ -2154,7 +2154,7 @@ static int ext4_setup_super(struct super_block *sb, struct ext4_super_block *es,
 	if (sbi->s_journal)
 		ext4_set_feature_journal_needs_recovery(sb);
 
-	ext4_commit_super(sb, 1);
+	err = ext4_commit_super(sb, 1);
 done:
 	if (test_opt(sb, DEBUG))
 		printk(KERN_INFO "[EXT4 FS bs=%lu, gc=%u, "

@@ -2166,7 +2166,7 @@ static int ext4_setup_super(struct super_block *sb, struct ext4_super_block *es,
 			sbi->s_mount_opt, sbi->s_mount_opt2);
 
 	cleancache_init_fs(sb);
-	return res;
+	return err;
 }
 
 int ext4_alloc_flex_bg_array(struct super_block *sb, ext4_group_t ngroup)

@@ -4760,11 +4760,7 @@ static int ext4_commit_super(struct super_block *sb, int sync)
 		unlock_buffer(sbh);
 		error = __sync_dirty_buffer(sbh,
 			REQ_SYNC | (test_opt(sb, BARRIER) ? REQ_FUA : 0));
-		if (error)
-			return error;
-
-		error = buffer_write_io_error(sbh);
-		if (error) {
+		if (buffer_write_io_error(sbh)) {
 			ext4_msg(sb, KERN_ERR, "I/O error while writing "
 			       "superblock");
 			clear_buffer_write_io_error(sbh);

@@ -5165,8 +5161,12 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 			if (sbi->s_journal)
 				ext4_clear_journal_err(sb, es);
 			sbi->s_mount_state = le16_to_cpu(es->s_state);
-			if (!ext4_setup_super(sb, es, 0))
-				sb->s_flags &= ~SB_RDONLY;
+
+			err = ext4_setup_super(sb, es, 0);
+			if (err)
+				goto restore_opts;
+
+			sb->s_flags &= ~SB_RDONLY;
 			if (ext4_has_feature_mmp(sb))
 				if (ext4_multi_mount_protect(sb,
 						le64_to_cpu(es->s_mmp_block))) {

@@ -5190,8 +5190,11 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 	}
 
 	ext4_setup_system_zone(sb);
-	if (sbi->s_journal == NULL && !(old_sb_flags & SB_RDONLY))
-		ext4_commit_super(sb, 1);
+	if (sbi->s_journal == NULL && !(old_sb_flags & SB_RDONLY)) {
+		err = ext4_commit_super(sb, 1);
+		if (err)
+			goto restore_opts;
+	}
 
 #ifdef CONFIG_QUOTA
 	/* Release old quota file names */

Signature · 1 line

2.17.0.484.g0c8726318c-goog

Theodore Y. Ts'o

maintainer

2018-05-14 03:46 UTC #6 lore raw

Quoted 20 lines · Jaegeuk Kim

When remounting ext4 from ro to rw, currently it allows its transition, even if ext4_commit_super() returns EIO. Even worse thing is, after that, fs/buffer complains buffer dirty bits like:

 Call trace:
 [<ffffff9750c259dc>] mark_buffer_dirty+0x184/0x1a4
 [<ffffff9750cb398c>] __ext4_handle_dirty_super+0x4c/0xfc
 [<ffffff9750c7a9fc>] ext4_file_open+0x154/0x1c0
 [<ffffff9750bea51c>] do_dentry_open+0x114/0x2d0
 [<ffffff9750bea75c>] vfs_open+0x5c/0x94
 [<ffffff9750bf879c>] path_openat+0x668/0xfe8
 [<ffffff9750bf8088>] do_filp_open+0x74/0x120
 [<ffffff9750beac98>] do_sys_open+0x148/0x254
 [<ffffff9750beade0>] SyS_openat+0x10/0x18
 [<ffffff9750a83ab0>] el0_svc_naked+0x24/0x28
 EXT4-fs (dm-1): previous I/O error to superblock detected
 Buffer I/O error on dev dm-1, logical block 0, lost sync page write
 EXT4-fs (dm-1): re-mounted. Opts: (null)
 Buffer I/O error on dev dm-1, logical block 80, lost async page write

Quoted 5 lines

Cc "Theodore Ts'o" <[email protected]>
Cc Andreas Dilger <[email protected]>
Cc [email protected]
Cc Jaegeuk Kim <[email protected]>
Signed-off-by Jaegeuk Kim <[email protected]>

Applied with a fix up to ext4_fill_super() when it calls ext4_setup_super() with the changed error return semantics.

- Ted

fs/ext4/super.c +5 -1

index aac33c155363..1388e56bb3f5 100644
@@ -4254,8 +4254,12 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 		goto failed_mount4;
 	}
 
-	if (ext4_setup_super(sb, es, sb_rdonly(sb)))
+	ret = ext4_setup_super(sb, es, sb_rdonly(sb));
+	if (ret == -EROFS) {
 		sb->s_flags |= SB_RDONLY;
+		ret = 0;
+	} else if (ret)
+		goto failed_mount4a;
 
 	/* determine the minimum size of new large inodes, if present */
 	if (sbi->s_inode_size > EXT4_GOOD_OLD_INODE_SIZE &&