On Wed, Aug 21, 2019 at 04:03:08PM +0900, Damien Le Moal wrote:
> zonefs is a very simple file system exposing each zone of a zoned
> block device as a file. zonefs is in fact closer to a raw block device
> access interface than to a full feature POSIX file system.
<skipping to the good part>
> +/*
> + * Read super block information from the device.
> + */
> +static int zonefs_read_super(struct super_block *sb)
> +{
> + const void *zero_page = (const void *) __va(page_to_phys(ZERO_PAGE(0)));
> + struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
> + struct zonefs_super *super;
> + struct bio bio;
> + struct bio_vec bio_vec;
> + struct page *page;
> + u32 crc, stored_crc;
> + int ret;
> +
> + page = alloc_page(GFP_KERNEL);
> + if (!page)
> + return -ENOMEM;
> +
> + bio_init(&bio, &bio_vec, 1);
> + bio.bi_iter.bi_sector = 0;
> + bio_set_dev(&bio, sb->s_bdev);
> + bio_set_op_attrs(&bio, REQ_OP_READ, 0);
> + bio_add_page(&bio, page, PAGE_SIZE, 0);
> +
> + ret = submit_bio_wait(&bio);
> + if (ret)
> + goto out;
> +
> + super = page_address(page);
> +
> + stored_crc = super->s_crc;
> + super->s_crc = 0;
> + crc = crc32_le(ZONEFS_MAGIC, (unsigned char *)super,
> + sizeof(struct zonefs_super));
> + if (crc != stored_crc) {
> + zonefs_err(sb, "Invalid checksum (Expected 0x%08x, got 0x%08x)",
> + crc, stored_crc);
> + ret = -EIO;
> + goto out;
> + }
> +
> + ret = -EINVAL;
> + if (le32_to_cpu(super->s_magic) != ZONEFS_MAGIC)
> + goto out;
> +
> + sbi->s_features = le64_to_cpu(super->s_features);
> + if (sbi->s_features & ~((1ULL << ZONEFS_F_NUM) - 1)) {
Most other filesystems would do:
#define ZONEFS_F_ALL_FEATURES (ZONEFS_F_UID | ZONEFS_F_GID ...)
and then this becomes:
if (sbi->s_features & ~ZONEFS_F_ALL_FEATURES)
> + zonefs_err(sb, "Unknown features set\n");
Also it might help to print out the invalid s_features values so that
when you get help questions you can distinguish between a corrupted
superblock and a new fs on an old kernel.
> + goto out;
> + }
> +
> +
> + if (zonefs_has_feature(sbi, ZONEFS_F_UID)) {
> + sbi->s_uid = make_kuid(current_user_ns(),
> + le32_to_cpu(super->s_uid));
> + if (!uid_valid(sbi->s_uid)) {
> + zonefs_err(sb, "Invalid UID feature\n");
> + goto out;
> + }
> + }
> + if (zonefs_has_feature(sbi, ZONEFS_F_GID)) {
> + sbi->s_gid = make_kgid(current_user_ns(),
> + le32_to_cpu(super->s_gid));
> + if (!gid_valid(sbi->s_gid)) {
> + zonefs_err(sb, "Invalid GID feature\n");
> + goto out;
> + }
> + }
> +
> + if (zonefs_has_feature(sbi, ZONEFS_F_PERM))
> + sbi->s_perm = le32_to_cpu(super->s_perm);
> +
> + if (memcmp(super->s_reserved, zero_page, sizeof(super->s_reserved))) {
Er... memchr_inv?
Otherwise looks reasonable enough. How do you test zonedfs?
--D
> + zonefs_err(sb, "Reserved area is being used\n");
> + goto out;
> + }
> +
> + uuid_copy(&sbi->s_uuid, &super->s_uuid);
> + ret = 0;
> +
> +out:
> + __free_page(page);
> +
> + return ret;
> +}
> +
> +/*
> + * Check that the device is zoned. If it is, get the list of zones and create
> + * sub-directories and files according to the device zone configuration.
> + */
> +static int zonefs_fill_super(struct super_block *sb, void *data, int silent)
> +{
> + struct zonefs_sb_info *sbi;
> + struct blk_zone *zones;
> + struct inode *inode;
> + enum zonefs_ztype t;
> + int ret;
> +
> + /* Check device type */
> + if (!bdev_is_zoned(sb->s_bdev)) {
> + zonefs_err(sb, "Not a zoned block device\n");
> + return -EINVAL;
> + }
> +
> + /* Initialize super block information */
> + sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
> + if (!sbi)
> + return -ENOMEM;
> +
> + sb->s_fs_info = sbi;
> + sb->s_magic = ZONEFS_MAGIC;
> + sb->s_maxbytes = MAX_LFS_FILESIZE;
> + sb->s_op = &zonefs_sops;
> + sb->s_time_gran = 1;
> +
> + /*
> + * The block size is always equal to the device physical sector size to
> + * ensure that writes on 512e disks (512B logical block and 4KB
> + * physical block) are always aligned.
> + */
> + sb_set_blocksize(sb, bdev_physical_block_size(sb->s_bdev));
> + sbi->s_blocksize_mask = sb->s_blocksize - 1;
> +
> + sbi->s_uid = GLOBAL_ROOT_UID;
> + sbi->s_gid = GLOBAL_ROOT_GID;
> + sbi->s_perm = 0640; /* S_IRUSR | S_IWUSR | S_IRGRP */
> +
> + ret = zonefs_read_super(sb);
> + if (ret)
> + return ret;
> +
> + zones = zonefs_get_zone_info(sb);
> + if (IS_ERR(zones))
> + return PTR_ERR(zones);
> +
> + pr_info("zonefs: Mounting %s, %u zones",
> + sb->s_id, blkdev_nr_zones(sb->s_bdev));
> +
> + /* Create root directory inode */
> + ret = -ENOMEM;
> + inode = new_inode(sb);
> + if (!inode)
> + goto out;
> +
> + inode->i_ino = get_next_ino();
> + inode->i_mode = S_IFDIR | 0755;
> + inode->i_ctime = inode->i_mtime = inode->i_atime = current_time(inode);
> + inode->i_op = &simple_dir_inode_operations;
> + inode->i_fop = &simple_dir_operations;
> + inode->i_size = sizeof(struct dentry) * 2;
> + set_nlink(inode, 2);
> +
> + sb->s_root = d_make_root(inode);
> + if (!sb->s_root)
> + goto out;
> +
> + /* Create and populate zone groups */
> + for (t = ZONEFS_ZTYPE_CNV; t < ZONEFS_ZTYPE_MAX; t++) {
> + ret = zonefs_create_zgroup(sb, zones, t);
> + if (ret)
> + break;
> + }
> +
> +out:
> + kvfree(zones);
> +
> + return ret;
> +}
> +
> +static struct dentry *zonefs_mount(struct file_system_type *fs_type,
> + int flags, const char *dev_name, void *data)
> +{
> + return mount_bdev(fs_type, flags, dev_name, data, zonefs_fill_super);
> +}
> +
> +static void zonefs_kill_super(struct super_block *sb)
> +{
> + struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
> +
> + kfree(sbi);
> + if (sb->s_root)
> + d_genocide(sb->s_root);
> + kill_block_super(sb);
> +}
> +
> +/*
> + * File system definition and registration.
> + */
> +static struct file_system_type zonefs_type = {
> + .owner = THIS_MODULE,
> + .name = "zonefs",
> + .mount = zonefs_mount,
> + .kill_sb = zonefs_kill_super,
> + .fs_flags = FS_REQUIRES_DEV,
> +};
> +
> +static int __init zonefs_init_inodecache(void)
> +{
> + zonefs_inode_cachep = kmem_cache_create("zonefs_inode_cache",
> + sizeof(struct zonefs_inode_info), 0,
> + (SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD | SLAB_ACCOUNT),
> + NULL);
> + if (zonefs_inode_cachep == NULL)
> + return -ENOMEM;
> + return 0;
> +}
> +
> +static void zonefs_destroy_inodecache(void)
> +{
> + /*
> + * Make sure all delayed rcu free inodes are flushed before we
> + * destroy the inode cache.
> + */
> + rcu_barrier();
> + kmem_cache_destroy(zonefs_inode_cachep);
> +}
> +
> +static int __init zonefs_init(void)
> +{
> + int ret;
> +
> + BUILD_BUG_ON(sizeof(struct zonefs_super) != ZONEFS_SUPER_SIZE);
> +
> + ret = zonefs_init_inodecache();
> + if (ret)
> + return ret;
> +
> + ret = register_filesystem(&zonefs_type);
> + if (ret) {
> + zonefs_destroy_inodecache();
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static void __exit zonefs_exit(void)
> +{
> + zonefs_destroy_inodecache();
> + unregister_filesystem(&zonefs_type);
> +}
> +
> +MODULE_AUTHOR("Damien Le Moal");
> +MODULE_DESCRIPTION("Zone file system for zoned block devices");
> +MODULE_LICENSE("GPL");
> +module_init(zonefs_init);
> +module_exit(zonefs_exit);
> diff --git a/fs/zonefs/zonefs.h b/fs/zonefs/zonefs.h
> new file mode 100644
> index 000000000000..aae59f797ee2
> --- /dev/null
> +++ b/fs/zonefs/zonefs.h
> @@ -0,0 +1,177 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Simple zone file system for zoned block devices.
> + *
> + * Copyright (C) 2019 Western Digital Corporation or its affiliates.
> + */
> +#ifndef __ZONEFS_H__
> +#define __ZONEFS_H__
> +
> +#include <linux/fs.h>
> +#include <linux/magic.h>
> +#include <linux/uuid.h>
> +#include <linux/mutex.h>
> +#include <linux/rwsem.h>
> +
> +/*
> + * Maximum length of file names: this only needs to be large enough to fit
> + * the zone group directory names and a decimal value of the start sector of
> + * the zones for file names. 16 characters is plenty.
> + */
> +#define ZONEFS_NAME_MAX 16
> +
> +/*
> + * Zone types: ZONEFS_ZTYPE_SEQ is used for all sequential zone types
> + * defined in linux/blkzoned.h, that is, BLK_ZONE_TYPE_SEQWRITE_REQ and
> + * BLK_ZONE_TYPE_SEQWRITE_PREF.
> + */
> +enum zonefs_ztype {
> + ZONEFS_ZTYPE_CNV,
> + ZONEFS_ZTYPE_SEQ,
> + ZONEFS_ZTYPE_MAX,
> +};
> +
> +static inline enum zonefs_ztype zonefs_zone_type(struct blk_zone *zone)
> +{
> + if (zone->type == BLK_ZONE_TYPE_CONVENTIONAL)
> + return ZONEFS_ZTYPE_CNV;
> + return ZONEFS_ZTYPE_SEQ;
> +}
> +
> +/*
> + * Inode private data.
> + */
> +struct zonefs_inode_info {
> + struct inode i_vnode;
> + enum zonefs_ztype i_ztype;
> + sector_t i_zsector;
> + loff_t i_wpoffset;
> + loff_t i_max_size;
> + struct mutex i_truncate_mutex;
> + struct rw_semaphore i_mmap_sem;
> +};
> +
> +static inline struct zonefs_inode_info *ZONEFS_I(struct inode *inode)
> +{
> + return container_of(inode, struct zonefs_inode_info, i_vnode);
> +}
> +
> +static inline bool zonefs_file_is_conv(struct inode *inode)
> +{
> + return ZONEFS_I(inode)->i_ztype == ZONEFS_ZTYPE_CNV;
> +}
> +
> +static inline bool zonefs_file_is_seq(struct inode *inode)
> +{
> + return ZONEFS_I(inode)->i_ztype == ZONEFS_ZTYPE_SEQ;
> +}
> +
> +/*
> + * Start sector on disk of a file zone.
> + */
> +static inline loff_t zonefs_file_start_sector(struct inode *inode)
> +{
> + return ZONEFS_I(inode)->i_zsector;
> +}
> +
> +/*
> + * Maximum possible size of a file (i.e. the zone size).
> + */
> +static inline loff_t zonefs_file_max_size(struct inode *inode)
> +{
> + return ZONEFS_I(inode)->i_max_size;
> +}
> +
> +/*
> + * On-disk super block (block 0).
> + */
> +#define ZONEFS_SUPER_SIZE 4096
> +struct zonefs_super {
> +
> + /* Magic number */
> + __le32 s_magic;
> +
> + /* Checksum */
> + __le32 s_crc;
> +
> + /* Features */
> + __le64 s_features;
> +
> + /* 128-bit uuid */
> + uuid_t s_uuid;
> +
> + /* UID/GID to use for files */
> + __le32 s_uid;
> + __le32 s_gid;
> +
> + /* File permissions */
> + __le32 s_perm;
> +
> + /* Padding to ZONEFS_SUPER_SIZE bytes */
> + __u8 s_reserved[4052];
> +
> +} __packed;
> +
> +/*
> + * Feature flags: used on disk in the s_features field of struct zonefs_super
> + * and in-memory in the s_feartures field of struct zonefs_sb_info.
> + */
> +enum zonefs_features {
> + /*
> + * Use a zone start sector value as file name.
> + */
> + ZONEFS_F_STARTSECT_NAME,
> + /*
> + * Aggregate contiguous conventional zones into a single file.
> + */
> + ZONEFS_F_AGRCNV,
> + /*
> + * Use super block specified UID for files instead of default.
> + */
> + ZONEFS_F_UID,
> + /*
> + * Use super block specified GID for files instead of default.
> + */
> + ZONEFS_F_GID,
> + /*
> + * Use super block specified file permissions instead of default 640.
> + */
> + ZONEFS_F_PERM,
> +
> + ZONEFS_F_NUM,
> +};
> +
> +/*
> + * In-memory Super block information.
> + */
> +struct zonefs_sb_info {
> +
> + unsigned long long s_features;
> + kuid_t s_uid; /* File owner UID */
> + kgid_t s_gid; /* File owner GID */
> + umode_t s_perm; /* File permissions */
> + uuid_t s_uuid;
> +
> + loff_t s_blocksize_mask;
> + unsigned int s_nr_zones[ZONEFS_ZTYPE_MAX];
> +};
> +
> +static inline struct zonefs_sb_info *ZONEFS_SB(struct super_block *sb)
> +{
> + return sb->s_fs_info;
> +}
> +
> +static inline bool zonefs_has_feature(struct zonefs_sb_info *sbi,
> + enum zonefs_features f)
> +{
> + return sbi->s_features & (1ULL << f);
> +}
> +
> +#define zonefs_info(sb, format, args...) \
> + pr_info("zonefs (%s): " format, sb->s_id, ## args)
> +#define zonefs_err(sb, format, args...) \
> + pr_err("zonefs (%s) ERROR: " format, sb->s_id, ## args)
> +#define zonefs_warn(sb, format, args...) \
> + pr_warn("zonefs (%s) WARN: " format, sb->s_id, ## args)
> +
> +#endif
> diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h
> index 1274c692e59c..3be20c774142 100644
> --- a/include/uapi/linux/magic.h
> +++ b/include/uapi/linux/magic.h
> @@ -86,6 +86,7 @@
> #define NSFS_MAGIC 0x6e736673
> #define BPF_FS_MAGIC 0xcafe4a11
> #define AAFS_MAGIC 0x5a3c69f0
> +#define ZONEFS_MAGIC 0x5a4f4653
>
> /* Since UDF 2.01 is ISO 13346 based... */
> #define UDF_SUPER_MAGIC 0x15013346
> --
> 2.21.0
>
