[PATCH v2 22/34] zonefs: use the generic emergency read-only state

[Christian Brauner <brauner@kernel.org>]

Set SB_STATE_EMERGENCY_RO instead of a private bit and drop the checks
the VFS does now. /proc/mounts and statfs() report the filesystem as
read-only again. zonefs_set_emergency_ro() still prints the warning
once. The check in zonefs_seq_file_write_close() stays so a failed zone
close doesn't make the filesystem read-only a second time. And so does
the one in zonefs_file_write_iter() because the loop driver, nfs localio
and others call ->write_iter() without rw_verify_area().

Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
---
 fs/zonefs/file.c   | 10 ++++------
 fs/zonefs/super.c  | 11 +----------
 fs/zonefs/zonefs.h | 15 ---------------
 3 files changed, 5 insertions(+), 31 deletions(-)

diff --git a/fs/zonefs/file.c b/fs/zonefs/file.c
index 8959b6b36a83..e5f8c9bca662 100644
--- a/fs/zonefs/file.c
+++ b/fs/zonefs/file.c
@@ -299,7 +299,7 @@ static vm_fault_t zonefs_filemap_page_mkwrite(struct vm_fault *vmf)
 	struct inode *inode = file_inode(vmf->vma->vm_file);
 	vm_fault_t ret;
 
-	if (unlikely(IS_IMMUTABLE(inode) || zonefs_emergency_ro(inode->i_sb)))
+	if (unlikely(IS_IMMUTABLE(inode)))
 		return VM_FAULT_SIGBUS;
 
 	/*
@@ -601,7 +601,8 @@ static ssize_t zonefs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	if (unlikely(IS_IMMUTABLE(inode)))
 		return -EPERM;
 
-	if (sb_rdonly(inode->i_sb) || zonefs_emergency_ro(inode->i_sb))
+	/* loop and others call ->write_iter() without rw_verify_area() */
+	if (sb_rdonly(inode->i_sb) || sb_emergency_ro(inode->i_sb))
 		return -EROFS;
 
 	/* Write operations beyond the zone capacity are not allowed */
@@ -788,9 +789,6 @@ static int zonefs_file_open(struct inode *inode, struct file *file)
 {
 	int ret;
 
-	if ((file->f_mode & FMODE_WRITE) && zonefs_emergency_ro(inode->i_sb))
-		return -EROFS;
-
 	file->f_mode |= FMODE_CAN_ODIRECT;
 	ret = generic_file_open(inode, file);
 	if (ret)
@@ -832,7 +830,7 @@ static void zonefs_seq_file_write_close(struct inode *inode)
 			 * file system read-only.
 			 */
 			if (z->z_flags & ZONEFS_ZONE_OPEN &&
-			    !sb_rdonly(sb) && !zonefs_emergency_ro(sb)) {
+			    !sb_rdonly(sb) && !sb_emergency_ro(sb)) {
 				zonefs_warn(sb,
 					"closing zone at %llu failed %d\n",
 					z->z_sector, ret);
diff --git a/fs/zonefs/super.c b/fs/zonefs/super.c
index e7c97b75c601..342dcc261906 100644
--- a/fs/zonefs/super.c
+++ b/fs/zonefs/super.c
@@ -253,8 +253,7 @@ static void zonefs_inode_update_mode(struct inode *inode)
  */
 void zonefs_set_emergency_ro(struct super_block *sb)
 {
-	if (sb_rdonly(sb) ||
-	    test_and_set_bit(ZONEFS_SB_EMERGENCY_RO, &ZONEFS_SB(sb)->s_state))
+	if (sb_rdonly(sb) || !sb_set_emergency_ro(sb))
 		return;
 
 	zonefs_warn(sb, "remounting filesystem read-only\n");
@@ -549,9 +548,6 @@ static int zonefs_inode_setattr(const struct mnt_idmap *idmap,
 	struct inode *inode = d_inode(dentry);
 	int ret;
 
-	if (unlikely(zonefs_emergency_ro(inode->i_sb)))
-		return -EROFS;
-
 	if (unlikely(IS_IMMUTABLE(inode)))
 		return -EPERM;
 
@@ -1382,11 +1378,6 @@ static int zonefs_reconfigure(struct fs_context *fc)
 	struct super_block *sb = fc->root->d_sb;
 	struct zonefs_sb_info *sbi = sb->s_fs_info;
 
-	/* An error made the file system read-only until it is unmounted. */
-	if (sb_rdonly(sb) && !(fc->sb_flags & SB_RDONLY) &&
-	    zonefs_emergency_ro(sb))
-		return -EROFS;
-
 	sync_filesystem(fc->root->d_sb);
 	/* Copy new options from ctx into sbi. */
 	sbi->s_mount_opts = ctx->s_mount_opts;
diff --git a/fs/zonefs/zonefs.h b/fs/zonefs/zonefs.h
index b14822cb9c02..24029c0e23db 100644
--- a/fs/zonefs/zonefs.h
+++ b/fs/zonefs/zonefs.h
@@ -241,16 +241,6 @@ struct zonefs_sb_info {
 	bool			s_sysfs_registered;
 	struct kobject		s_kobj;
 	struct completion	s_kobj_unregister;
-
-	unsigned long		s_state;
-};
-
-/*
- * Super block state bits (s_state).
- */
-enum {
-	/* An error made the file system read-only until it is unmounted */
-	ZONEFS_SB_EMERGENCY_RO,
 };
 
 static inline struct zonefs_sb_info *ZONEFS_SB(struct super_block *sb)
@@ -258,11 +248,6 @@ static inline struct zonefs_sb_info *ZONEFS_SB(struct super_block *sb)
 	return sb->s_fs_info;
 }
 
-static inline bool zonefs_emergency_ro(struct super_block *sb)
-{
-	return test_bit(ZONEFS_SB_EMERGENCY_RO, &ZONEFS_SB(sb)->s_state);
-}
-
 #define zonefs_info(sb, format, args...)	\
 	pr_info("zonefs (%s): " format, sb->s_id, ## args)
 #define zonefs_err(sb, format, args...)		\

-- 
2.53.0