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![Johannes Thumshirn](/assets/img/avatar_default.png)
NVMe Zoned Namespace introduced the concept of active zones, which are zones in the implicit open, explicit open or closed condition. Drives may have a limit on the number of zones that can be simultaneously active. This potential limitation translate into a risk for applications to see write IO errors due to this limit if the zone of a file being written to is not already active when a write request is issued. To avoid these potential errors, the zone of a file can explicitly be made active using an open zone command when the file is open for the first time. If the zone open command succeeds, the application is then guaranteed that write requests can be processed. This indirect management of active zones relies on the maximum number of open zones of a drive, which is always lower or equal to the maximum number of active zones. On the first open of a sequential zone file, send a REQ_OP_ZONE_OPEN command to the block device. Conversely, on the last release of a zone file and send a REQ_OP_ZONE_CLOSE to the device if the zone is not full or empty. As truncating a zone file to 0 or max can deactivate a zone as well, we need to serialize against truncates and also be careful not to close a zone as the file may still be open for writing, e.g. the user called ftruncate(). If the zone file is not open and a process does a truncate(), then no close operation is needed. Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
202 lines
5 KiB
C
202 lines
5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Simple zone file system for zoned block devices.
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*
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* Copyright (C) 2019 Western Digital Corporation or its affiliates.
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*/
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#ifndef __ZONEFS_H__
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#define __ZONEFS_H__
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#include <linux/fs.h>
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#include <linux/magic.h>
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#include <linux/uuid.h>
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#include <linux/mutex.h>
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#include <linux/rwsem.h>
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/*
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* Maximum length of file names: this only needs to be large enough to fit
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* the zone group directory names and a decimal zone number for file names.
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* 16 characters is plenty.
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*/
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#define ZONEFS_NAME_MAX 16
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/*
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* Zone types: ZONEFS_ZTYPE_SEQ is used for all sequential zone types
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* defined in linux/blkzoned.h, that is, BLK_ZONE_TYPE_SEQWRITE_REQ and
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* BLK_ZONE_TYPE_SEQWRITE_PREF.
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*/
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enum zonefs_ztype {
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ZONEFS_ZTYPE_CNV,
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ZONEFS_ZTYPE_SEQ,
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ZONEFS_ZTYPE_MAX,
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};
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static inline enum zonefs_ztype zonefs_zone_type(struct blk_zone *zone)
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{
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if (zone->type == BLK_ZONE_TYPE_CONVENTIONAL)
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return ZONEFS_ZTYPE_CNV;
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return ZONEFS_ZTYPE_SEQ;
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}
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#define ZONEFS_ZONE_OPEN (1 << 0)
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/*
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* In-memory inode data.
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*/
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struct zonefs_inode_info {
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struct inode i_vnode;
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/* File zone type */
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enum zonefs_ztype i_ztype;
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/* File zone start sector (512B unit) */
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sector_t i_zsector;
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/* File zone write pointer position (sequential zones only) */
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loff_t i_wpoffset;
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/* File maximum size */
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loff_t i_max_size;
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/* File zone size */
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loff_t i_zone_size;
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/*
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* To serialise fully against both syscall and mmap based IO and
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* sequential file truncation, two locks are used. For serializing
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* zonefs_seq_file_truncate() against zonefs_iomap_begin(), that is,
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* file truncate operations against block mapping, i_truncate_mutex is
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* used. i_truncate_mutex also protects against concurrent accesses
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* and changes to the inode private data, and in particular changes to
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* a sequential file size on completion of direct IO writes.
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* Serialization of mmap read IOs with truncate and syscall IO
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* operations is done with i_mmap_sem in addition to i_truncate_mutex.
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* Only zonefs_seq_file_truncate() takes both lock (i_mmap_sem first,
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* i_truncate_mutex second).
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*/
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struct mutex i_truncate_mutex;
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struct rw_semaphore i_mmap_sem;
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/* guarded by i_truncate_mutex */
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unsigned int i_wr_refcnt;
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unsigned int i_flags;
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};
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static inline struct zonefs_inode_info *ZONEFS_I(struct inode *inode)
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{
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return container_of(inode, struct zonefs_inode_info, i_vnode);
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}
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/*
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* On-disk super block (block 0).
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*/
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#define ZONEFS_LABEL_LEN 64
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#define ZONEFS_UUID_SIZE 16
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#define ZONEFS_SUPER_SIZE 4096
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struct zonefs_super {
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/* Magic number */
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__le32 s_magic;
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/* Checksum */
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__le32 s_crc;
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/* Volume label */
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char s_label[ZONEFS_LABEL_LEN];
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/* 128-bit uuid */
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__u8 s_uuid[ZONEFS_UUID_SIZE];
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/* Features */
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__le64 s_features;
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/* UID/GID to use for files */
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__le32 s_uid;
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__le32 s_gid;
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/* File permissions */
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__le32 s_perm;
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/* Padding to ZONEFS_SUPER_SIZE bytes */
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__u8 s_reserved[3988];
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} __packed;
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/*
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* Feature flags: specified in the s_features field of the on-disk super
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* block struct zonefs_super and in-memory in the s_feartures field of
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* struct zonefs_sb_info.
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*/
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enum zonefs_features {
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/*
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* Aggregate contiguous conventional zones into a single file.
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*/
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ZONEFS_F_AGGRCNV = 1ULL << 0,
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/*
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* Use super block specified UID for files instead of default 0.
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*/
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ZONEFS_F_UID = 1ULL << 1,
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/*
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* Use super block specified GID for files instead of default 0.
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*/
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ZONEFS_F_GID = 1ULL << 2,
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/*
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* Use super block specified file permissions instead of default 640.
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*/
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ZONEFS_F_PERM = 1ULL << 3,
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};
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#define ZONEFS_F_DEFINED_FEATURES \
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(ZONEFS_F_AGGRCNV | ZONEFS_F_UID | ZONEFS_F_GID | ZONEFS_F_PERM)
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/*
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* Mount options for zone write pointer error handling.
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*/
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#define ZONEFS_MNTOPT_ERRORS_RO (1 << 0) /* Make zone file readonly */
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#define ZONEFS_MNTOPT_ERRORS_ZRO (1 << 1) /* Make zone file offline */
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#define ZONEFS_MNTOPT_ERRORS_ZOL (1 << 2) /* Make zone file offline */
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#define ZONEFS_MNTOPT_ERRORS_REPAIR (1 << 3) /* Remount read-only */
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#define ZONEFS_MNTOPT_ERRORS_MASK \
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(ZONEFS_MNTOPT_ERRORS_RO | ZONEFS_MNTOPT_ERRORS_ZRO | \
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ZONEFS_MNTOPT_ERRORS_ZOL | ZONEFS_MNTOPT_ERRORS_REPAIR)
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#define ZONEFS_MNTOPT_EXPLICIT_OPEN (1 << 4) /* Explicit open/close of zones on open/close */
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/*
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* In-memory Super block information.
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*/
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struct zonefs_sb_info {
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unsigned long s_mount_opts;
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spinlock_t s_lock;
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unsigned long long s_features;
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kuid_t s_uid;
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kgid_t s_gid;
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umode_t s_perm;
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uuid_t s_uuid;
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unsigned int s_zone_sectors_shift;
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unsigned int s_nr_files[ZONEFS_ZTYPE_MAX];
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loff_t s_blocks;
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loff_t s_used_blocks;
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unsigned int s_max_open_zones;
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atomic_t s_open_zones;
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};
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static inline struct zonefs_sb_info *ZONEFS_SB(struct super_block *sb)
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{
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return sb->s_fs_info;
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}
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#define zonefs_info(sb, format, args...) \
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pr_info("zonefs (%s): " format, sb->s_id, ## args)
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#define zonefs_err(sb, format, args...) \
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pr_err("zonefs (%s) ERROR: " format, sb->s_id, ## args)
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#define zonefs_warn(sb, format, args...) \
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pr_warn("zonefs (%s) WARNING: " format, sb->s_id, ## args)
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#endif
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