[PATCH v2 1/2] ocfs2: Add ocfs2_emergency_state helper and apply to setattr

[Ahmet Eray Karadag <eraykrdg1@gmail.com>]

To centralize error checking, follow the pattern of other filesystems
like ext4 (which uses `ext4_emergency_state()`), and prepare for
future enhancements, this patch introduces a new helper function:
`ocfs2_emergency_state()`.

The purpose of this helper is to provide a single, unified location
for checking all filesystem-level emergency conditions. In this
initial implementation, the function only checks for the existing
hard and soft read-only modes, returning -EROFS if either is set.

This provides a foundation where future checks (e.g., for fatal error
states returning -EIO, or shutdown states) can be easily added in
one place.

This patch also adds this new check to the beginning of
`ocfs2_setattr()`. This ensures that operations like `ftruncate`
(which triggered the original BUG) fail-fast with -EROFS when the
filesystem is already in a read-only state.

Suggested-by: Heming Zhao <heming.zhao@suse.com>
Co-developed-by: Albin Babu Varghese <albinbabuvarghese20@gmail.com>
Signed-off-by: Albin Babu Varghese <albinbabuvarghese20@gmail.com>
Signed-off-by: Ahmet Eray Karadag <eraykrdg1@gmail.com>
---
v2:
 - Introducing new function `ocfs2_is_readonly` to lower the cost
 - Using unlikely for status check
---
 fs/ocfs2/file.c  |  6 ++++++
 fs/ocfs2/ocfs2.h | 18 ++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 21d797ccccd0..253b4f300127 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1137,6 +1137,12 @@ int ocfs2_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 					from_kgid(&init_user_ns, attr->ia_gid) : 0);
 
 	/* ensuring we don't even attempt to truncate a symlink */
+	status = ocfs2_emergency_state(osb);
+	if (unlikely(status)) {
+		mlog_errno(status);
+		goto bail;
+	}
+
 	if (S_ISLNK(inode->i_mode))
 		attr->ia_valid &= ~ATTR_SIZE;
 
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index 6aaa94c554c1..b018c535226e 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -680,6 +680,24 @@ static inline int ocfs2_is_soft_readonly(struct ocfs2_super *osb)
 	return ret;
 }
 
+static inline int ocfs2_is_readonly(struct ocfs2_super *osb)
+{
+	int ret;
+	spin_lock(&osb->osb_lock);
+	ret = osb->osb_flags & (OCFS2_OSB_SOFT_RO | OCFS2_OSB_HARD_RO);
+	spin_unlock(&osb->osb_lock);
+
+	return ret
+}
+
+static inline int ocfs2_emergency_state(struct ocfs2_super *osb)
+{
+	if (ocfs2_is_readonly(osb)) {
+		return -EROFS;
+	}
+	return 0;
+}
+
 static inline int ocfs2_clusterinfo_valid(struct ocfs2_super *osb)
 {
 	return (osb->s_feature_incompat &
-- 
2.43.0