linux-kernel - [RFC 1/6] fs: add frozen sb state helpers

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Message-ID: <20250326112220.1988619-2-mcgrof@kernel.org>
Date: Wed, 26 Mar 2025 04:22:15 -0700
From: Luis Chamberlain <mcgrof@...nel.org>
To: jack@...e.cz,
	hch@...radead.org,
	James.Bottomley@...senPartnership.com,
	david@...morbit.com,
	rafael@...nel.org,
	djwong@...nel.org,
	pavel@...nel.org,
	song@...nel.org
Cc: linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	gost.dev@...sung.com,
	Luis Chamberlain <mcgrof@...nel.org>
Subject: [RFC 1/6] fs: add frozen sb state helpers

Provide helpers so that we can check a superblock frozen state.
This will make subsequent changes easier to read. This makes
no functional changes.

Reviewed-by: Jan Kara <jack@...e.cz>
Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
---
 fs/ext4/ext4_jbd2.c |  2 +-
 fs/gfs2/sys.c       |  2 +-
 fs/quota/quota.c    |  3 ++-
 fs/super.c          |  8 ++++----
 fs/xfs/xfs_trans.c  |  3 +--
 include/linux/fs.h  | 22 ++++++++++++++++++++++
 6 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/fs/ext4/ext4_jbd2.c b/fs/ext4/ext4_jbd2.c
index 135e278c832e..5f5c2121d2ad 100644
--- a/fs/ext4/ext4_jbd2.c
+++ b/fs/ext4/ext4_jbd2.c
@@ -75,7 +75,7 @@ static int ext4_journal_check_start(struct super_block *sb)
 	if (WARN_ON_ONCE(sb_rdonly(sb)))
 		return -EROFS;
 
-	WARN_ON(sb->s_writers.frozen == SB_FREEZE_COMPLETE);
+	WARN_ON(sb_is_frozen(sb));
 	journal = EXT4_SB(sb)->s_journal;
 	/*
 	 * Special case here: if the journal has aborted behind our
diff --git a/fs/gfs2/sys.c b/fs/gfs2/sys.c
index ecc699f8d9fc..08ec5904a208 100644
--- a/fs/gfs2/sys.c
+++ b/fs/gfs2/sys.c
@@ -156,7 +156,7 @@ static ssize_t uuid_show(struct gfs2_sbd *sdp, char *buf)
 static ssize_t freeze_show(struct gfs2_sbd *sdp, char *buf)
 {
 	struct super_block *sb = sdp->sd_vfs;
-	int frozen = (sb->s_writers.frozen == SB_UNFROZEN) ? 0 : 1;
+	int frozen = sb_is_unfrozen(sb) ? 0 : 1;
 
 	return snprintf(buf, PAGE_SIZE, "%d\n", frozen);
 }
diff --git a/fs/quota/quota.c b/fs/quota/quota.c
index 7c2b75a44485..9b4e0a80f386 100644
--- a/fs/quota/quota.c
+++ b/fs/quota/quota.c
@@ -890,11 +890,12 @@ static struct super_block *quotactl_block(const char __user *special, int cmd)
 	sb = user_get_super(dev, excl);
 	if (!sb)
 		return ERR_PTR(-ENODEV);
-	if (thawed && sb->s_writers.frozen != SB_UNFROZEN) {
+	if (thawed && !sb_is_unfrozen(sb)) {
 		if (excl)
 			up_write(&sb->s_umount);
 		else
 			up_read(&sb->s_umount);
+
 		/* Wait for sb to unfreeze */
 		sb_start_write(sb);
 		sb_end_write(sb);
diff --git a/fs/super.c b/fs/super.c
index 97a17f9d9023..117bd1bfe09f 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -1029,7 +1029,7 @@ int reconfigure_super(struct fs_context *fc)
 
 	if (fc->sb_flags_mask & ~MS_RMT_MASK)
 		return -EINVAL;
-	if (sb->s_writers.frozen != SB_UNFROZEN)
+	if (!(sb_is_unfrozen(sb)))
 		return -EBUSY;
 
 	retval = security_sb_remount(sb, fc->security);
@@ -1053,7 +1053,7 @@ int reconfigure_super(struct fs_context *fc)
 			__super_lock_excl(sb);
 			if (!sb->s_root)
 				return 0;
-			if (sb->s_writers.frozen != SB_UNFROZEN)
+			if (!sb_is_unfrozen(sb))
 				return -EBUSY;
 			remount_ro = !sb_rdonly(sb);
 		}
@@ -2009,7 +2009,7 @@ int freeze_super(struct super_block *sb, enum freeze_holder who)
 	atomic_inc(&sb->s_active);
 
 retry:
-	if (sb->s_writers.frozen == SB_FREEZE_COMPLETE) {
+	if (sb_is_frozen(sb)) {
 		if (may_freeze(sb, who))
 			ret = !!WARN_ON_ONCE(freeze_inc(sb, who) == 1);
 		else
@@ -2019,7 +2019,7 @@ int freeze_super(struct super_block *sb, enum freeze_holder who)
 		return ret;
 	}
 
-	if (sb->s_writers.frozen != SB_UNFROZEN) {
+	if (sb_is_unfrozen(sb)) {
 		ret = wait_for_partially_frozen(sb);
 		if (ret) {
 			deactivate_locked_super(sb);
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index c6657072361a..3a5088865064 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -269,8 +269,7 @@ xfs_trans_alloc(
 	 * Zero-reservation ("empty") transactions can't modify anything, so
 	 * they're allowed to run while we're frozen.
 	 */
-	WARN_ON(resp->tr_logres > 0 &&
-		mp->m_super->s_writers.frozen == SB_FREEZE_COMPLETE);
+	WARN_ON(resp->tr_logres > 0 && sb_is_frozen(mp->m_super));
 	ASSERT(!(flags & XFS_TRANS_RES_FDBLKS) ||
 	       xfs_has_lazysbcount(mp));
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 016b0fe1536e..1d9a9c557e1a 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1971,6 +1971,28 @@ static inline bool sb_start_intwrite_trylock(struct super_block *sb)
 	return __sb_start_write_trylock(sb, SB_FREEZE_FS);
 }
 
+/**
+ * sb_is_frozen - is superblock frozen
+ * @sb: the super to check
+ *
+ * Returns true if the super is frozen.
+ */
+static inline bool sb_is_frozen(struct super_block *sb)
+{
+	return sb->s_writers.frozen == SB_FREEZE_COMPLETE;
+}
+
+/**
+ * sb_is_unfrozen - is superblock unfrozen
+ * @sb: the super to check
+ *
+ * Returns true if the super is unfrozen.
+ */
+static inline bool sb_is_unfrozen(struct super_block *sb)
+{
+	return sb->s_writers.frozen == SB_UNFROZEN;
+}
+
 bool inode_owner_or_capable(struct mnt_idmap *idmap,
 			    const struct inode *inode);
 
-- 
2.47.2