linux-ext4 - [PATCH 2/3] ext4: reflect error codes from ext4_multi_mount

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Date:   Thu, 27 Apr 2023 23:16:01 -0400
From:   "Theodore Ts'o" <tytso@....edu>
To:     Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc:     Andreas Dilger <adilger@...ger.ca>,
        Jason Yan <yanaijie@...wei.com>,
        "Theodore Ts'o" <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>
Subject: [PATCH 2/3] ext4: reflect error codes from ext4_multi_mount_protect() to its callers

This will allow more fine-grained errno codes to be returned by the
mount system call.

Cc: Andreas Dilger <adilger.kernel@...ger.ca>
Signed-off-by: Theodore Ts'o <tytso@....edu>
---
 fs/ext4/mmp.c   |  9 ++++++++-
 fs/ext4/super.c | 14 +++++++++-----
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
index 4681fff6665f..4022bc713421 100644
--- a/fs/ext4/mmp.c
+++ b/fs/ext4/mmp.c
@@ -282,6 +282,7 @@ int ext4_multi_mount_protect(struct super_block *sb,
 	if (mmp_block < le32_to_cpu(es->s_first_data_block) ||
 	    mmp_block >= ext4_blocks_count(es)) {
 		ext4_warning(sb, "Invalid MMP block in superblock");
+		retval = -EINVAL;
 		goto failed;
 	}
 
@@ -307,6 +308,7 @@ int ext4_multi_mount_protect(struct super_block *sb,
 
 	if (seq == EXT4_MMP_SEQ_FSCK) {
 		dump_mmp_msg(sb, mmp, "fsck is running on the filesystem");
+		retval = -EBUSY;
 		goto failed;
 	}
 
@@ -320,6 +322,7 @@ int ext4_multi_mount_protect(struct super_block *sb,
 
 	if (schedule_timeout_interruptible(HZ * wait_time) != 0) {
 		ext4_warning(sb, "MMP startup interrupted, failing mount\n");
+		retval = -ETIMEDOUT;
 		goto failed;
 	}
 
@@ -330,6 +333,7 @@ int ext4_multi_mount_protect(struct super_block *sb,
 	if (seq != le32_to_cpu(mmp->mmp_seq)) {
 		dump_mmp_msg(sb, mmp,
 			     "Device is already active on another node.");
+		retval = -EBUSY;
 		goto failed;
 	}
 
@@ -349,6 +353,7 @@ int ext4_multi_mount_protect(struct super_block *sb,
 	 */
 	if (schedule_timeout_interruptible(HZ * wait_time) != 0) {
 		ext4_warning(sb, "MMP startup interrupted, failing mount");
+		retval = -ETIMEDOUT;
 		goto failed;
 	}
 
@@ -359,6 +364,7 @@ int ext4_multi_mount_protect(struct super_block *sb,
 	if (seq != le32_to_cpu(mmp->mmp_seq)) {
 		dump_mmp_msg(sb, mmp,
 			     "Device is already active on another node.");
+		retval = -EBUSY;
 		goto failed;
 	}
 
@@ -378,6 +384,7 @@ int ext4_multi_mount_protect(struct super_block *sb,
 		EXT4_SB(sb)->s_mmp_tsk = NULL;
 		ext4_warning(sb, "Unable to create kmmpd thread for %s.",
 			     sb->s_id);
+		retval = -ENOMEM;
 		goto failed;
 	}
 
@@ -385,5 +392,5 @@ int ext4_multi_mount_protect(struct super_block *sb,
 
 failed:
 	brelse(bh);
-	return 1;
+	return retval;
 }
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index b11907e1fab2..9a8af70815b1 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -5329,9 +5329,11 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
 			  ext4_has_feature_orphan_present(sb) ||
 			  ext4_has_feature_journal_needs_recovery(sb));
 
-	if (ext4_has_feature_mmp(sb) && !sb_rdonly(sb))
-		if (ext4_multi_mount_protect(sb, le64_to_cpu(es->s_mmp_block)))
+	if (ext4_has_feature_mmp(sb) && !sb_rdonly(sb)) {
+		err = ext4_multi_mount_protect(sb, le64_to_cpu(es->s_mmp_block));
+		if (err)
 			goto failed_mount3a;
+	}
 
 	/*
 	 * The first inode we look at is the journal inode.  Don't try
@@ -6566,12 +6568,14 @@ static int __ext4_remount(struct fs_context *fc, struct super_block *sb)
 				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))) {
+			if (ext4_has_feature_mmp(sb)) {
+				err = ext4_multi_mount_protect(sb,
+						le64_to_cpu(es->s_mmp_block));
+				if (err) {
 					err = -EROFS;
 					goto restore_opts;
 				}
+			}
 #ifdef CONFIG_QUOTA
 			enable_quota = 1;
 #endif
-- 
2.31.0