zonefs: Always do seq file write open accounting

The explicit_open mount option forces an explicitly open of the zone of
sequential files that are open for writing to ensure that the open file
can be written without the device failing write operations due to open
zone resources limit being exceeded. To implement this, zonefs accounts
all write open seq file when this mount option is used.

This accounting however can be easily performed even when the
explicit_open mount option is not used, thus allowing applications to
control zone resources on their own, without relying on open() system
call failures from zonefs.

To implement this, the helper zonefs_file_use_exp_open() is removed and
replaced with the helper zonefs_seq_file_need_wro() which test if a file
is a sequential file being open with write access. zonefs_open_zone()
and zonefs_close_zone() are renamed respectively to
zonefs_seq_file_write_open() and zonefs_seq_file_write_close() and
modified to update the s_wro_seq_files counter regardless of the
explicit_open mount option use.

If the explicit_open mount option is used, zonefs_seq_file_write_open()
execute an explicit zone open operation for a sequential file open for
writing for the first time, as before.

Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Hans Holmberg <hans.holmberg@wdc.com>

1 files changed, 46 insertions, 34 deletions

diff --git a/fs/zonefs/super.c b/fs/zonefs/super.c
index dafacde65659..02dbdec32b2f 100644
--- a/fs/zonefs/super.c
+++ b/fs/zonefs/super.c
@@ -1009,13 +1009,13 @@ inode_unlock:
 	return ret;
 }
 
-static inline bool zonefs_file_use_exp_open(struct inode *inode, struct file *file)
+/*
+ * Write open accounting is done only for sequential files.
+ */
+static inline bool zonefs_seq_file_need_wro(struct inode *inode,
+					    struct file *file)
 {
 	struct zonefs_inode_info *zi = ZONEFS_I(inode);
-	struct zonefs_sb_info *sbi = ZONEFS_SB(inode->i_sb);
-
-	if (!(sbi->s_mount_opts & ZONEFS_MNTOPT_EXPLICIT_OPEN))
-		return false;
 
 	if (zi->i_ztype != ZONEFS_ZTYPE_SEQ)
 		return false;
@@ -1026,30 +1026,33 @@ static inline bool zonefs_file_use_exp_open(struct inode *inode, struct file *fi
 	return true;
 }
 
-static int zonefs_open_zone(struct inode *inode)
+static int zonefs_seq_file_write_open(struct inode *inode)
 {
 	struct zonefs_inode_info *zi = ZONEFS_I(inode);
-	struct zonefs_sb_info *sbi = ZONEFS_SB(inode->i_sb);
 	int ret = 0;
 
 	mutex_lock(&zi->i_truncate_mutex);
 
 	if (!zi->i_wr_refcnt) {
+		struct zonefs_sb_info *sbi = ZONEFS_SB(inode->i_sb);
 		unsigned int wro = atomic_inc_return(&sbi->s_wro_seq_files);
 
-		if (wro > sbi->s_max_wro_seq_files) {
-			atomic_dec(&sbi->s_wro_seq_files);
-			ret = -EBUSY;
-			goto unlock;
-		}
+		if (sbi->s_mount_opts & ZONEFS_MNTOPT_EXPLICIT_OPEN) {
 
-		if (i_size_read(inode) < zi->i_max_size) {
-			ret = zonefs_zone_mgmt(inode, REQ_OP_ZONE_OPEN);
-			if (ret) {
+			if (wro > sbi->s_max_wro_seq_files) {
 				atomic_dec(&sbi->s_wro_seq_files);
+				ret = -EBUSY;
 				goto unlock;
 			}
-			zi->i_flags |= ZONEFS_ZONE_OPEN;
+
+			if (i_size_read(inode) < zi->i_max_size) {
+				ret = zonefs_zone_mgmt(inode, REQ_OP_ZONE_OPEN);
+				if (ret) {
+					atomic_dec(&sbi->s_wro_seq_files);
+					goto unlock;
+				}
+				zi->i_flags |= ZONEFS_ZONE_OPEN;
+			}
 		}
 	}
 
@@ -1069,30 +1072,31 @@ static int zonefs_file_open(struct inode *inode, struct file *file)
 	if (ret)
 		return ret;
 
-	if (zonefs_file_use_exp_open(inode, file))
-		return zonefs_open_zone(inode);
+	if (zonefs_seq_file_need_wro(inode, file))
+		return zonefs_seq_file_write_open(inode);
 
 	return 0;
 }
 
-static void zonefs_close_zone(struct inode *inode)
+static void zonefs_seq_file_write_close(struct inode *inode)
 {
 	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+	struct super_block *sb = inode->i_sb;
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
 	int ret = 0;
 
 	mutex_lock(&zi->i_truncate_mutex);
-	zi->i_wr_refcnt--;
-	if (!zi->i_wr_refcnt) {
-		struct zonefs_sb_info *sbi = ZONEFS_SB(inode->i_sb);
-		struct super_block *sb = inode->i_sb;
 
-		/*
-		 * If the file zone is full, it is not open anymore and we only
-		 * need to decrement the open count.
-		 */
-		if (!(zi->i_flags & ZONEFS_ZONE_OPEN))
-			goto dec;
+	zi->i_wr_refcnt--;
+	if (zi->i_wr_refcnt)
+		goto unlock;
 
+	/*
+	 * The file zone may not be open anymore (e.g. the file was truncated to
+	 * its maximum size or it was fully written). For this case, we only
+	 * need to decrement the write open count.
+	 */
+	if (zi->i_flags & ZONEFS_ZONE_OPEN) {
 		ret = zonefs_zone_mgmt(inode, REQ_OP_ZONE_CLOSE);
 		if (ret) {
 			__zonefs_io_error(inode, false);
@@ -1104,14 +1108,22 @@ static void zonefs_close_zone(struct inode *inode)
 			 */
 			if (zi->i_flags & ZONEFS_ZONE_OPEN &&
 			    !(sb->s_flags & SB_RDONLY)) {
-				zonefs_warn(sb, "closing zone failed, remounting filesystem read-only\n");
+				zonefs_warn(sb,
+					"closing zone at %llu failed %d\n",
+					zi->i_zsector, ret);
+				zonefs_warn(sb,
+					"remounting filesystem read-only\n");
 				sb->s_flags |= SB_RDONLY;
 			}
+			goto unlock;
 		}
+
 		zi->i_flags &= ~ZONEFS_ZONE_OPEN;
-dec:
-		atomic_dec(&sbi->s_wro_seq_files);
 	}
+
+	atomic_dec(&sbi->s_wro_seq_files);
+
+unlock:
 	mutex_unlock(&zi->i_truncate_mutex);
 }
 
@@ -1123,8 +1135,8 @@ static int zonefs_file_release(struct inode *inode, struct file *file)
 	 * the zone has gone offline or read-only). Make sure we don't fail the
 	 * close(2) for user-space.
 	 */
-	if (zonefs_file_use_exp_open(inode, file))
-		zonefs_close_zone(inode);
+	if (zonefs_seq_file_need_wro(inode, file))
+		zonefs_seq_file_write_close(inode);
 
 	return 0;
 }