zonefs changes for 5.9-rc1

A single change for this cycle adding support for zone capacities
 smaller than the zone size, from Johannes.
 
 Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
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Merge tag 'zonefs-5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/zonefs

Pull zonefs update from Damien Le Moal:
 "A single change for this cycle adding support for zone capacities
  smaller than the zone size, from Johannes"

* tag 'zonefs-5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/zonefs:
  zonefs: update documentation to reflect zone size vs capacity
  zonefs: add zone-capacity support

Documentation/filesystems/zonefs.rst

@@ -110,14 +110,14 @@ contain files named "0", "1", "2", ... The file numbers also represent
 increasing zone start sector on the device.
 
 All read and write operations to zone files are not allowed beyond the file
-maximum size, that is, beyond the zone size. Any access exceeding the zone
-size is failed with the -EFBIG error.
+maximum size, that is, beyond the zone capacity. Any access exceeding the zone
+capacity is failed with the -EFBIG error.
 
 Creating, deleting, renaming or modifying any attribute of files and
 sub-directories is not allowed.
 
 The number of blocks of a file as reported by stat() and fstat() indicates the
-size of the file zone, or in other words, the maximum file size.
+capacity of the zone file, or in other words, the maximum file size.
 
 Conventional zone files
 -----------------------
@@ -156,8 +156,8 @@ all accepted.
 
 Truncating sequential zone files is allowed only down to 0, in which case, the
 zone is reset to rewind the file zone write pointer position to the start of
-the zone, or up to the zone size, in which case the file's zone is transitioned
-to the FULL state (finish zone operation).
+the zone, or up to the zone capacity, in which case the file's zone is
+transitioned to the FULL state (finish zone operation).
 
 Format options
 --------------
@@ -324,7 +324,7 @@ file size set to 0. This is necessary as the write pointer of read-only zones
 is defined as invalib by the ZBC and ZAC standards, making it impossible to
 discover the amount of data that has been written to the zone. In the case of a
 read-only zone discovered at run-time, as indicated in the previous section.
-the size of the zone file is left unchanged from its last updated value.
+The size of the zone file is left unchanged from its last updated value.
 
 Zonefs User Space Tools
 =======================
@@ -401,8 +401,9 @@ append-writes to the file::
     # ls -l /mnt/seq/0
     -rw-r----- 1 root root 0 Nov 25 13:49 /mnt/seq/0
 
-Since files are statically mapped to zones on the disk, the number of blocks of
-a file as reported by stat() and fstat() indicates the size of the file zone::
+Since files are statically mapped to zones on the disk, the number of blocks
+of a file as reported by stat() and fstat() indicates the capacity of the file
+zone::
 
     # stat /mnt/seq/0
     File: /mnt/seq/0
@@ -416,5 +417,6 @@ a file as reported by stat() and fstat() indicates the size of the file zone::
 
 The number of blocks of the file ("Blocks") in units of 512B blocks gives the
 maximum file size of 524288 * 512 B = 256 MB, corresponding to the device zone
-size in this example. Of note is that the "IO block" field always indicates the
-minimum I/O size for writes and corresponds to the device physical sector size.
+capacity in this example. Of note is that the "IO block" field always
+indicates the minimum I/O size for writes and corresponds to the device
+physical sector size.

fs/zonefs/super.c

@@ -335,7 +335,7 @@ static void zonefs_io_error(struct inode *inode, bool write)
 	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
 	unsigned int noio_flag;
 	unsigned int nr_zones =
-		zi->i_max_size >> (sbi->s_zone_sectors_shift + SECTOR_SHIFT);
+		zi->i_zone_size >> (sbi->s_zone_sectors_shift + SECTOR_SHIFT);
 	struct zonefs_ioerr_data err = {
 		.inode = inode,
 		.write = write,
@@ -398,7 +398,7 @@ static int zonefs_file_truncate(struct inode *inode, loff_t isize)
 		goto unlock;
 
 	ret = blkdev_zone_mgmt(inode->i_sb->s_bdev, op, zi->i_zsector,
-			       zi->i_max_size >> SECTOR_SHIFT, GFP_NOFS);
+			       zi->i_zone_size >> SECTOR_SHIFT, GFP_NOFS);
 	if (ret) {
 		zonefs_err(inode->i_sb,
 			   "Zone management operation at %llu failed %d",
@@ -1053,14 +1053,16 @@ static void zonefs_init_file_inode(struct inode *inode, struct blk_zone *zone,
 
 	zi->i_ztype = type;
 	zi->i_zsector = zone->start;
+	zi->i_zone_size = zone->len << SECTOR_SHIFT;
+
 	zi->i_max_size = min_t(loff_t, MAX_LFS_FILESIZE,
-			       zone->len << SECTOR_SHIFT);
+			       zone->capacity << SECTOR_SHIFT);
 	zi->i_wpoffset = zonefs_check_zone_condition(inode, zone, true, true);
 
 	inode->i_uid = sbi->s_uid;
 	inode->i_gid = sbi->s_gid;
 	inode->i_size = zi->i_wpoffset;
-	inode->i_blocks = zone->len;
+	inode->i_blocks = zi->i_max_size >> SECTOR_SHIFT;
 
 	inode->i_op = &zonefs_file_inode_operations;
 	inode->i_fop = &zonefs_file_operations;
@@ -1167,12 +1169,18 @@ static int zonefs_create_zgroup(struct zonefs_zone_data *zd,
 				if (zonefs_zone_type(next) != type)
 					break;
 				zone->len += next->len;
+				zone->capacity += next->capacity;
 				if (next->cond == BLK_ZONE_COND_READONLY &&
 				    zone->cond != BLK_ZONE_COND_OFFLINE)
 					zone->cond = BLK_ZONE_COND_READONLY;
 				else if (next->cond == BLK_ZONE_COND_OFFLINE)
 					zone->cond = BLK_ZONE_COND_OFFLINE;
 			}
+			if (zone->capacity != zone->len) {
+				zonefs_err(sb, "Invalid conventional zone capacity\n");
+				ret = -EINVAL;
+				goto free;
+			}
 		}
 
 		/*

fs/zonefs/zonefs.h

@@ -56,6 +56,9 @@ struct zonefs_inode_info {
 	/* File maximum size */
 	loff_t			i_max_size;
 
+	/* File zone size */
+	loff_t			i_zone_size;
+
 	/*
 	 * To serialise fully against both syscall and mmap based IO and
 	 * sequential file truncation, two locks are used. For serializing