Merge tag 'for-5.14-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave...

[linux-2.6-microblaze.git] / fs / zonefs / super.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Simple file system for zoned block devices exposing zones as files.
 *
 * Copyright (C) 2019 Western Digital Corporation or its affiliates.
 */
#include <linux/module.h>
#include <linux/pagemap.h>
#include <linux/magic.h>
#include <linux/iomap.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/statfs.h>
#include <linux/writeback.h>
#include <linux/quotaops.h>
#include <linux/seq_file.h>
#include <linux/parser.h>
#include <linux/uio.h>
#include <linux/mman.h>
#include <linux/sched/mm.h>
#include <linux/crc32.h>
#include <linux/task_io_accounting_ops.h>

#include "zonefs.h"

#define CREATE_TRACE_POINTS
#include "trace.h"

static inline int zonefs_zone_mgmt(struct inode *inode,
                                   enum req_opf op)
{
        struct zonefs_inode_info *zi = ZONEFS_I(inode);
        int ret;

        lockdep_assert_held(&zi->i_truncate_mutex);

        trace_zonefs_zone_mgmt(inode, op);
        ret = blkdev_zone_mgmt(inode->i_sb->s_bdev, op, zi->i_zsector,
                               zi->i_zone_size >> SECTOR_SHIFT, GFP_NOFS);
        if (ret) {
                zonefs_err(inode->i_sb,
                           "Zone management operation %s at %llu failed %d\n",
                           blk_op_str(op), zi->i_zsector, ret);
                return ret;
        }

        return 0;
}

static inline void zonefs_i_size_write(struct inode *inode, loff_t isize)
{
        struct zonefs_inode_info *zi = ZONEFS_I(inode);

        i_size_write(inode, isize);
        /*
         * A full zone is no longer open/active and does not need
         * explicit closing.
         */
        if (isize >= zi->i_max_size)
                zi->i_flags &= ~ZONEFS_ZONE_OPEN;
}

static int zonefs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
                              unsigned int flags, struct iomap *iomap,
                              struct iomap *srcmap)
{
        struct zonefs_inode_info *zi = ZONEFS_I(inode);
        struct super_block *sb = inode->i_sb;
        loff_t isize;

        /* All I/Os should always be within the file maximum size */
        if (WARN_ON_ONCE(offset + length > zi->i_max_size))
                return -EIO;

        /*
         * Sequential zones can only accept direct writes. This is already
         * checked when writes are issued, so warn if we see a page writeback
         * operation.
         */
        if (WARN_ON_ONCE(zi->i_ztype == ZONEFS_ZTYPE_SEQ &&
                         (flags & IOMAP_WRITE) && !(flags & IOMAP_DIRECT)))
                return -EIO;

        /*
         * For conventional zones, all blocks are always mapped. For sequential
         * zones, all blocks after always mapped below the inode size (zone
         * write pointer) and unwriten beyond.
         */
        mutex_lock(&zi->i_truncate_mutex);
        isize = i_size_read(inode);
        if (offset >= isize)
                iomap->type = IOMAP_UNWRITTEN;
        else
                iomap->type = IOMAP_MAPPED;
        if (flags & IOMAP_WRITE)
                length = zi->i_max_size - offset;
        else
                length = min(length, isize - offset);
        mutex_unlock(&zi->i_truncate_mutex);

        iomap->offset = ALIGN_DOWN(offset, sb->s_blocksize);
        iomap->length = ALIGN(offset + length, sb->s_blocksize) - iomap->offset;
        iomap->bdev = inode->i_sb->s_bdev;
        iomap->addr = (zi->i_zsector << SECTOR_SHIFT) + iomap->offset;

        trace_zonefs_iomap_begin(inode, iomap);

        return 0;
}

static const struct iomap_ops zonefs_iomap_ops = {
        .iomap_begin    = zonefs_iomap_begin,
};

static int zonefs_readpage(struct file *unused, struct page *page)
{
        return iomap_readpage(page, &zonefs_iomap_ops);
}

static void zonefs_readahead(struct readahead_control *rac)
{
        iomap_readahead(rac, &zonefs_iomap_ops);
}

/*
 * Map blocks for page writeback. This is used only on conventional zone files,
 * which implies that the page range can only be within the fixed inode size.
 */
static int zonefs_map_blocks(struct iomap_writepage_ctx *wpc,
                             struct inode *inode, loff_t offset)
{
        struct zonefs_inode_info *zi = ZONEFS_I(inode);

        if (WARN_ON_ONCE(zi->i_ztype != ZONEFS_ZTYPE_CNV))
                return -EIO;
        if (WARN_ON_ONCE(offset >= i_size_read(inode)))
                return -EIO;

        /* If the mapping is already OK, nothing needs to be done */
        if (offset >= wpc->iomap.offset &&
            offset < wpc->iomap.offset + wpc->iomap.length)
                return 0;

        return zonefs_iomap_begin(inode, offset, zi->i_max_size - offset,
                                  IOMAP_WRITE, &wpc->iomap, NULL);
}

static const struct iomap_writeback_ops zonefs_writeback_ops = {
        .map_blocks             = zonefs_map_blocks,
};

static int zonefs_writepage(struct page *page, struct writeback_control *wbc)
{
        struct iomap_writepage_ctx wpc = { };

        return iomap_writepage(page, wbc, &wpc, &zonefs_writeback_ops);
}

static int zonefs_writepages(struct address_space *mapping,
                             struct writeback_control *wbc)
{
        struct iomap_writepage_ctx wpc = { };

        return iomap_writepages(mapping, wbc, &wpc, &zonefs_writeback_ops);
}

static int zonefs_swap_activate(struct swap_info_struct *sis,
                                struct file *swap_file, sector_t *span)
{
        struct inode *inode = file_inode(swap_file);
        struct zonefs_inode_info *zi = ZONEFS_I(inode);

        if (zi->i_ztype != ZONEFS_ZTYPE_CNV) {
                zonefs_err(inode->i_sb,
                           "swap file: not a conventional zone file\n");
                return -EINVAL;
        }

        return iomap_swapfile_activate(sis, swap_file, span, &zonefs_iomap_ops);
}

static const struct address_space_operations zonefs_file_aops = {
        .readpage               = zonefs_readpage,
        .readahead              = zonefs_readahead,
        .writepage              = zonefs_writepage,
        .writepages             = zonefs_writepages,
        .set_page_dirty         = __set_page_dirty_nobuffers,
        .releasepage            = iomap_releasepage,
        .invalidatepage         = iomap_invalidatepage,
        .migratepage            = iomap_migrate_page,
        .is_partially_uptodate  = iomap_is_partially_uptodate,
        .error_remove_page      = generic_error_remove_page,
        .direct_IO              = noop_direct_IO,
        .swap_activate          = zonefs_swap_activate,
};

static void zonefs_update_stats(struct inode *inode, loff_t new_isize)
{
        struct super_block *sb = inode->i_sb;
        struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
        loff_t old_isize = i_size_read(inode);
        loff_t nr_blocks;

        if (new_isize == old_isize)
                return;

        spin_lock(&sbi->s_lock);

        /*
         * This may be called for an update after an IO error.
         * So beware of the values seen.
         */
        if (new_isize < old_isize) {
                nr_blocks = (old_isize - new_isize) >> sb->s_blocksize_bits;
                if (sbi->s_used_blocks > nr_blocks)
                        sbi->s_used_blocks -= nr_blocks;
                else
                        sbi->s_used_blocks = 0;
        } else {
                sbi->s_used_blocks +=
                        (new_isize - old_isize) >> sb->s_blocksize_bits;
                if (sbi->s_used_blocks > sbi->s_blocks)
                        sbi->s_used_blocks = sbi->s_blocks;
        }

        spin_unlock(&sbi->s_lock);
}

/*
 * Check a zone condition and adjust its file inode access permissions for
 * offline and readonly zones. Return the inode size corresponding to the
 * amount of readable data in the zone.
 */
static loff_t zonefs_check_zone_condition(struct inode *inode,
                                          struct blk_zone *zone, bool warn,
                                          bool mount)
{
        struct zonefs_inode_info *zi = ZONEFS_I(inode);

        switch (zone->cond) {
        case BLK_ZONE_COND_OFFLINE:
                /*
                 * Dead zone: make the inode immutable, disable all accesses
                 * and set the file size to 0 (zone wp set to zone start).
                 */
                if (warn)
                        zonefs_warn(inode->i_sb, "inode %lu: offline zone\n",
                                    inode->i_ino);
                inode->i_flags |= S_IMMUTABLE;
                inode->i_mode &= ~0777;
                zone->wp = zone->start;
                return 0;
        case BLK_ZONE_COND_READONLY:
                /*
                 * The write pointer of read-only zones is invalid. If such a
                 * zone is found during mount, the file size cannot be retrieved
                 * so we treat the zone as offline (mount == true case).
                 * Otherwise, keep the file size as it was when last updated
                 * so that the user can recover data. In both cases, writes are
                 * always disabled for the zone.
                 */
                if (warn)
                        zonefs_warn(inode->i_sb, "inode %lu: read-only zone\n",
                                    inode->i_ino);
                inode->i_flags |= S_IMMUTABLE;
                if (mount) {
                        zone->cond = BLK_ZONE_COND_OFFLINE;
                        inode->i_mode &= ~0777;
                        zone->wp = zone->start;
                        return 0;
                }
                inode->i_mode &= ~0222;
                return i_size_read(inode);
        case BLK_ZONE_COND_FULL:
                /* The write pointer of full zones is invalid. */
                return zi->i_max_size;
        default:
                if (zi->i_ztype == ZONEFS_ZTYPE_CNV)
                        return zi->i_max_size;
                return (zone->wp - zone->start) << SECTOR_SHIFT;
        }
}

struct zonefs_ioerr_data {
        struct inode    *inode;
        bool            write;
};

static int zonefs_io_error_cb(struct blk_zone *zone, unsigned int idx,
                              void *data)
{
        struct zonefs_ioerr_data *err = data;
        struct inode *inode = err->inode;
        struct zonefs_inode_info *zi = ZONEFS_I(inode);
        struct super_block *sb = inode->i_sb;
        struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
        loff_t isize, data_size;

        /*
         * Check the zone condition: if the zone is not "bad" (offline or
         * read-only), read errors are simply signaled to the IO issuer as long
         * as there is no inconsistency between the inode size and the amount of
         * data writen in the zone (data_size).
         */
        data_size = zonefs_check_zone_condition(inode, zone, true, false);
        isize = i_size_read(inode);
        if (zone->cond != BLK_ZONE_COND_OFFLINE &&
            zone->cond != BLK_ZONE_COND_READONLY &&
            !err->write && isize == data_size)
                return 0;

        /*
         * At this point, we detected either a bad zone or an inconsistency
         * between the inode size and the amount of data written in the zone.
         * For the latter case, the cause may be a write IO error or an external
         * action on the device. Two error patterns exist:
         * 1) The inode size is lower than the amount of data in the zone:
         *    a write operation partially failed and data was writen at the end
         *    of the file. This can happen in the case of a large direct IO
         *    needing several BIOs and/or write requests to be processed.
         * 2) The inode size is larger than the amount of data in the zone:
         *    this can happen with a deferred write error with the use of the
         *    device side write cache after getting successful write IO
         *    completions. Other possibilities are (a) an external corruption,
         *    e.g. an application reset the zone directly, or (b) the device
         *    has a serious problem (e.g. firmware bug).
         *
         * In all cases, warn about inode size inconsistency and handle the
         * IO error according to the zone condition and to the mount options.
         */
        if (zi->i_ztype == ZONEFS_ZTYPE_SEQ && isize != data_size)
                zonefs_warn(sb, "inode %lu: invalid size %lld (should be %lld)\n",
                            inode->i_ino, isize, data_size);

        /*
         * First handle bad zones signaled by hardware. The mount options
         * errors=zone-ro and errors=zone-offline result in changing the
         * zone condition to read-only and offline respectively, as if the
         * condition was signaled by the hardware.
         */
        if (zone->cond == BLK_ZONE_COND_OFFLINE ||
            sbi->s_mount_opts & ZONEFS_MNTOPT_ERRORS_ZOL) {
                zonefs_warn(sb, "inode %lu: read/write access disabled\n",
                            inode->i_ino);
                if (zone->cond != BLK_ZONE_COND_OFFLINE) {
                        zone->cond = BLK_ZONE_COND_OFFLINE;
                        data_size = zonefs_check_zone_condition(inode, zone,
                                                                false, false);
                }
        } else if (zone->cond == BLK_ZONE_COND_READONLY ||
                   sbi->s_mount_opts & ZONEFS_MNTOPT_ERRORS_ZRO) {
                zonefs_warn(sb, "inode %lu: write access disabled\n",
                            inode->i_ino);
                if (zone->cond != BLK_ZONE_COND_READONLY) {
                        zone->cond = BLK_ZONE_COND_READONLY;
                        data_size = zonefs_check_zone_condition(inode, zone,
                                                                false, false);
                }
        }

        /*
         * If the filesystem is mounted with the explicit-open mount option, we
         * need to clear the ZONEFS_ZONE_OPEN flag if the zone transitioned to
         * the read-only or offline condition, to avoid attempting an explicit
         * close of the zone when the inode file is closed.
         */
        if ((sbi->s_mount_opts & ZONEFS_MNTOPT_EXPLICIT_OPEN) &&
            (zone->cond == BLK_ZONE_COND_OFFLINE ||
             zone->cond == BLK_ZONE_COND_READONLY))
                zi->i_flags &= ~ZONEFS_ZONE_OPEN;

        /*
         * If error=remount-ro was specified, any error result in remounting
         * the volume as read-only.
         */
        if ((sbi->s_mount_opts & ZONEFS_MNTOPT_ERRORS_RO) && !sb_rdonly(sb)) {
                zonefs_warn(sb, "remounting filesystem read-only\n");
                sb->s_flags |= SB_RDONLY;
        }

        /*
         * Update block usage stats and the inode size  to prevent access to
         * invalid data.
         */
        zonefs_update_stats(inode, data_size);
        zonefs_i_size_write(inode, data_size);
        zi->i_wpoffset = data_size;

        return 0;
}

/*
 * When an file IO error occurs, check the file zone to see if there is a change
 * in the zone condition (e.g. offline or read-only). For a failed write to a
 * sequential zone, the zone write pointer position must also be checked to
 * eventually correct the file size and zonefs inode write pointer offset
 * (which can be out of sync with the drive due to partial write failures).
 */
static void __zonefs_io_error(struct inode *inode, bool write)
{
        struct zonefs_inode_info *zi = ZONEFS_I(inode);
        struct super_block *sb = inode->i_sb;
        struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
        unsigned int noio_flag;
        unsigned int nr_zones =
                zi->i_zone_size >> (sbi->s_zone_sectors_shift + SECTOR_SHIFT);
        struct zonefs_ioerr_data err = {
                .inode = inode,
                .write = write,
        };
        int ret;

        /*
         * Memory allocations in blkdev_report_zones() can trigger a memory
         * reclaim which may in turn cause a recursion into zonefs as well as
         * struct request allocations for the same device. The former case may
         * end up in a deadlock on the inode truncate mutex, while the latter
         * may prevent IO forward progress. Executing the report zones under
         * the GFP_NOIO context avoids both problems.
         */
        noio_flag = memalloc_noio_save();
        ret = blkdev_report_zones(sb->s_bdev, zi->i_zsector, nr_zones,
                                  zonefs_io_error_cb, &err);
        if (ret != nr_zones)
                zonefs_err(sb, "Get inode %lu zone information failed %d\n",
                           inode->i_ino, ret);
        memalloc_noio_restore(noio_flag);
}

static void zonefs_io_error(struct inode *inode, bool write)
{
        struct zonefs_inode_info *zi = ZONEFS_I(inode);

        mutex_lock(&zi->i_truncate_mutex);
        __zonefs_io_error(inode, write);
        mutex_unlock(&zi->i_truncate_mutex);
}

static int zonefs_file_truncate(struct inode *inode, loff_t isize)
{
        struct zonefs_inode_info *zi = ZONEFS_I(inode);
        loff_t old_isize;
        enum req_opf op;
        int ret = 0;

        /*
         * Only sequential zone files can be truncated and truncation is allowed
         * only down to a 0 size, which is equivalent to a zone reset, and to
         * the maximum file size, which is equivalent to a zone finish.
         */
        if (zi->i_ztype != ZONEFS_ZTYPE_SEQ)
                return -EPERM;

        if (!isize)
                op = REQ_OP_ZONE_RESET;
        else if (isize == zi->i_max_size)
                op = REQ_OP_ZONE_FINISH;
        else
                return -EPERM;

        inode_dio_wait(inode);

        /* Serialize against page faults */
        down_write(&zi->i_mmap_sem);

        /* Serialize against zonefs_iomap_begin() */
        mutex_lock(&zi->i_truncate_mutex);

        old_isize = i_size_read(inode);
        if (isize == old_isize)
                goto unlock;

        ret = zonefs_zone_mgmt(inode, op);
        if (ret)
                goto unlock;

        /*
         * If the mount option ZONEFS_MNTOPT_EXPLICIT_OPEN is set,
         * take care of open zones.
         */
        if (zi->i_flags & ZONEFS_ZONE_OPEN) {
                /*
                 * Truncating a zone to EMPTY or FULL is the equivalent of
                 * closing the zone. For a truncation to 0, we need to
                 * re-open the zone to ensure new writes can be processed.
                 * For a truncation to the maximum file size, the zone is
                 * closed and writes cannot be accepted anymore, so clear
                 * the open flag.
                 */
                if (!isize)
                        ret = zonefs_zone_mgmt(inode, REQ_OP_ZONE_OPEN);
                else
                        zi->i_flags &= ~ZONEFS_ZONE_OPEN;
        }

        zonefs_update_stats(inode, isize);
        truncate_setsize(inode, isize);
        zi->i_wpoffset = isize;

unlock:
        mutex_unlock(&zi->i_truncate_mutex);
        up_write(&zi->i_mmap_sem);

        return ret;
}

static int zonefs_inode_setattr(struct user_namespace *mnt_userns,
                                struct dentry *dentry, struct iattr *iattr)
{
        struct inode *inode = d_inode(dentry);
        int ret;

        if (unlikely(IS_IMMUTABLE(inode)))
                return -EPERM;

        ret = setattr_prepare(&init_user_ns, dentry, iattr);
        if (ret)
                return ret;

        /*
         * Since files and directories cannot be created nor deleted, do not
         * allow setting any write attributes on the sub-directories grouping
         * files by zone type.
         */
        if ((iattr->ia_valid & ATTR_MODE) && S_ISDIR(inode->i_mode) &&
            (iattr->ia_mode & 0222))
                return -EPERM;

        if (((iattr->ia_valid & ATTR_UID) &&
             !uid_eq(iattr->ia_uid, inode->i_uid)) ||
            ((iattr->ia_valid & ATTR_GID) &&
             !gid_eq(iattr->ia_gid, inode->i_gid))) {
                ret = dquot_transfer(inode, iattr);
                if (ret)
                        return ret;
        }

        if (iattr->ia_valid & ATTR_SIZE) {
                ret = zonefs_file_truncate(inode, iattr->ia_size);
                if (ret)
                        return ret;
        }

        setattr_copy(&init_user_ns, inode, iattr);

        return 0;
}

static const struct inode_operations zonefs_file_inode_operations = {
        .setattr        = zonefs_inode_setattr,
};

static int zonefs_file_fsync(struct file *file, loff_t start, loff_t end,
                             int datasync)
{
        struct inode *inode = file_inode(file);
        int ret = 0;

        if (unlikely(IS_IMMUTABLE(inode)))
                return -EPERM;

        /*
         * Since only direct writes are allowed in sequential files, page cache
         * flush is needed only for conventional zone files.
         */
        if (ZONEFS_I(inode)->i_ztype == ZONEFS_ZTYPE_CNV)
                ret = file_write_and_wait_range(file, start, end);
        if (!ret)
                ret = blkdev_issue_flush(inode->i_sb->s_bdev);

        if (ret)
                zonefs_io_error(inode, true);

        return ret;
}

static vm_fault_t zonefs_filemap_fault(struct vm_fault *vmf)
{
        struct zonefs_inode_info *zi = ZONEFS_I(file_inode(vmf->vma->vm_file));
        vm_fault_t ret;

        down_read(&zi->i_mmap_sem);
        ret = filemap_fault(vmf);
        up_read(&zi->i_mmap_sem);

        return ret;
}

static vm_fault_t zonefs_filemap_page_mkwrite(struct vm_fault *vmf)
{
        struct inode *inode = file_inode(vmf->vma->vm_file);
        struct zonefs_inode_info *zi = ZONEFS_I(inode);
        vm_fault_t ret;

        if (unlikely(IS_IMMUTABLE(inode)))
                return VM_FAULT_SIGBUS;

        /*
         * Sanity check: only conventional zone files can have shared
         * writeable mappings.
         */
        if (WARN_ON_ONCE(zi->i_ztype != ZONEFS_ZTYPE_CNV))
                return VM_FAULT_NOPAGE;

        sb_start_pagefault(inode->i_sb);
        file_update_time(vmf->vma->vm_file);

        /* Serialize against truncates */
        down_read(&zi->i_mmap_sem);
        ret = iomap_page_mkwrite(vmf, &zonefs_iomap_ops);
        up_read(&zi->i_mmap_sem);

        sb_end_pagefault(inode->i_sb);
        return ret;
}

static const struct vm_operations_struct zonefs_file_vm_ops = {
        .fault          = zonefs_filemap_fault,
        .map_pages      = filemap_map_pages,
        .page_mkwrite   = zonefs_filemap_page_mkwrite,
};

static int zonefs_file_mmap(struct file *file, struct vm_area_struct *vma)
{
        /*
         * Conventional zones accept random writes, so their files can support
         * shared writable mappings. For sequential zone files, only read
         * mappings are possible since there are no guarantees for write
         * ordering between msync() and page cache writeback.
         */
        if (ZONEFS_I(file_inode(file))->i_ztype == ZONEFS_ZTYPE_SEQ &&
            (vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
                return -EINVAL;

        file_accessed(file);
        vma->vm_ops = &zonefs_file_vm_ops;

        return 0;
}

static loff_t zonefs_file_llseek(struct file *file, loff_t offset, int whence)
{
        loff_t isize = i_size_read(file_inode(file));

        /*
         * Seeks are limited to below the zone size for conventional zones
         * and below the zone write pointer for sequential zones. In both
         * cases, this limit is the inode size.
         */
        return generic_file_llseek_size(file, offset, whence, isize, isize);
}

static int zonefs_file_write_dio_end_io(struct kiocb *iocb, ssize_t size,
                                        int error, unsigned int flags)
{
        struct inode *inode = file_inode(iocb->ki_filp);
        struct zonefs_inode_info *zi = ZONEFS_I(inode);

        if (error) {
                zonefs_io_error(inode, true);
                return error;
        }

        if (size && zi->i_ztype != ZONEFS_ZTYPE_CNV) {
                /*
                 * Note that we may be seeing completions out of order,
                 * but that is not a problem since a write completed
                 * successfully necessarily means that all preceding writes
                 * were also successful. So we can safely increase the inode
                 * size to the write end location.
                 */
                mutex_lock(&zi->i_truncate_mutex);
                if (i_size_read(inode) < iocb->ki_pos + size) {
                        zonefs_update_stats(inode, iocb->ki_pos + size);
                        zonefs_i_size_write(inode, iocb->ki_pos + size);
                }
                mutex_unlock(&zi->i_truncate_mutex);
        }

        return 0;
}

static const struct iomap_dio_ops zonefs_write_dio_ops = {
        .end_io                 = zonefs_file_write_dio_end_io,
};

static ssize_t zonefs_file_dio_append(struct kiocb *iocb, struct iov_iter *from)
{
        struct inode *inode = file_inode(iocb->ki_filp);
        struct zonefs_inode_info *zi = ZONEFS_I(inode);
        struct block_device *bdev = inode->i_sb->s_bdev;
        unsigned int max;
        struct bio *bio;
        ssize_t size;
        int nr_pages;
        ssize_t ret;

        max = queue_max_zone_append_sectors(bdev_get_queue(bdev));
        max = ALIGN_DOWN(max << SECTOR_SHIFT, inode->i_sb->s_blocksize);
        iov_iter_truncate(from, max);

        nr_pages = iov_iter_npages(from, BIO_MAX_VECS);
        if (!nr_pages)
                return 0;

        bio = bio_alloc(GFP_NOFS, nr_pages);
        bio_set_dev(bio, bdev);
        bio->bi_iter.bi_sector = zi->i_zsector;
        bio->bi_write_hint = iocb->ki_hint;
        bio->bi_ioprio = iocb->ki_ioprio;
        bio->bi_opf = REQ_OP_ZONE_APPEND | REQ_SYNC | REQ_IDLE;
        if (iocb->ki_flags & IOCB_DSYNC)
                bio->bi_opf |= REQ_FUA;

        ret = bio_iov_iter_get_pages(bio, from);
        if (unlikely(ret))
                goto out_release;

        size = bio->bi_iter.bi_size;
        task_io_account_write(size);

        if (iocb->ki_flags & IOCB_HIPRI)
                bio_set_polled(bio, iocb);

        ret = submit_bio_wait(bio);

        zonefs_file_write_dio_end_io(iocb, size, ret, 0);
        trace_zonefs_file_dio_append(inode, size, ret);

out_release:
        bio_release_pages(bio, false);
        bio_put(bio);

        if (ret >= 0) {
                iocb->ki_pos += size;
                return size;
        }

        return ret;
}

/*
 * Do not exceed the LFS limits nor the file zone size. If pos is under the
 * limit it becomes a short access. If it exceeds the limit, return -EFBIG.
 */
static loff_t zonefs_write_check_limits(struct file *file, loff_t pos,
                                        loff_t count)
{
        struct inode *inode = file_inode(file);
        struct zonefs_inode_info *zi = ZONEFS_I(inode);
        loff_t limit = rlimit(RLIMIT_FSIZE);
        loff_t max_size = zi->i_max_size;

        if (limit != RLIM_INFINITY) {
                if (pos >= limit) {
                        send_sig(SIGXFSZ, current, 0);
                        return -EFBIG;
                }
                count = min(count, limit - pos);
        }

        if (!(file->f_flags & O_LARGEFILE))
                max_size = min_t(loff_t, MAX_NON_LFS, max_size);

        if (unlikely(pos >= max_size))
                return -EFBIG;

        return min(count, max_size - pos);
}

static ssize_t zonefs_write_checks(struct kiocb *iocb, struct iov_iter *from)
{
        struct file *file = iocb->ki_filp;
        struct inode *inode = file_inode(file);
        struct zonefs_inode_info *zi = ZONEFS_I(inode);
        loff_t count;

        if (IS_SWAPFILE(inode))
                return -ETXTBSY;

        if (!iov_iter_count(from))
                return 0;

        if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT))
                return -EINVAL;

        if (iocb->ki_flags & IOCB_APPEND) {
                if (zi->i_ztype != ZONEFS_ZTYPE_SEQ)
                        return -EINVAL;
                mutex_lock(&zi->i_truncate_mutex);
                iocb->ki_pos = zi->i_wpoffset;
                mutex_unlock(&zi->i_truncate_mutex);
        }

        count = zonefs_write_check_limits(file, iocb->ki_pos,
                                          iov_iter_count(from));
        if (count < 0)
                return count;

        iov_iter_truncate(from, count);
        return iov_iter_count(from);
}

/*
 * Handle direct writes. For sequential zone files, this is the only possible
 * write path. For these files, check that the user is issuing writes
 * sequentially from the end of the file. This code assumes that the block layer
 * delivers write requests to the device in sequential order. This is always the
 * case if a block IO scheduler implementing the ELEVATOR_F_ZBD_SEQ_WRITE
 * elevator feature is being used (e.g. mq-deadline). The block layer always
 * automatically select such an elevator for zoned block devices during the
 * device initialization.
 */
static ssize_t zonefs_file_dio_write(struct kiocb *iocb, struct iov_iter *from)
{
        struct inode *inode = file_inode(iocb->ki_filp);
        struct zonefs_inode_info *zi = ZONEFS_I(inode);
        struct super_block *sb = inode->i_sb;
        bool sync = is_sync_kiocb(iocb);
        bool append = false;
        ssize_t ret, count;

        /*
         * For async direct IOs to sequential zone files, refuse IOCB_NOWAIT
         * as this can cause write reordering (e.g. the first aio gets EAGAIN
         * on the inode lock but the second goes through but is now unaligned).
         */
        if (zi->i_ztype == ZONEFS_ZTYPE_SEQ && !sync &&
            (iocb->ki_flags & IOCB_NOWAIT))
                return -EOPNOTSUPP;

        if (iocb->ki_flags & IOCB_NOWAIT) {
                if (!inode_trylock(inode))
                        return -EAGAIN;
        } else {
                inode_lock(inode);
        }

        count = zonefs_write_checks(iocb, from);
        if (count <= 0) {
                ret = count;
                goto inode_unlock;
        }

        if ((iocb->ki_pos | count) & (sb->s_blocksize - 1)) {
                ret = -EINVAL;
                goto inode_unlock;
        }

        /* Enforce sequential writes (append only) in sequential zones */
        if (zi->i_ztype == ZONEFS_ZTYPE_SEQ) {
                mutex_lock(&zi->i_truncate_mutex);
                if (iocb->ki_pos != zi->i_wpoffset) {
                        mutex_unlock(&zi->i_truncate_mutex);
                        ret = -EINVAL;
                        goto inode_unlock;
                }
                mutex_unlock(&zi->i_truncate_mutex);
                append = sync;
        }

        if (append)
                ret = zonefs_file_dio_append(iocb, from);
        else
                ret = iomap_dio_rw(iocb, from, &zonefs_iomap_ops,
                                   &zonefs_write_dio_ops, 0);
        if (zi->i_ztype == ZONEFS_ZTYPE_SEQ &&
            (ret > 0 || ret == -EIOCBQUEUED)) {
                if (ret > 0)
                        count = ret;
                mutex_lock(&zi->i_truncate_mutex);
                zi->i_wpoffset += count;
                mutex_unlock(&zi->i_truncate_mutex);
        }

inode_unlock:
        inode_unlock(inode);

        return ret;
}

static ssize_t zonefs_file_buffered_write(struct kiocb *iocb,
                                          struct iov_iter *from)
{
        struct inode *inode = file_inode(iocb->ki_filp);
        struct zonefs_inode_info *zi = ZONEFS_I(inode);
        ssize_t ret;

        /*
         * Direct IO writes are mandatory for sequential zone files so that the
         * write IO issuing order is preserved.
         */
        if (zi->i_ztype != ZONEFS_ZTYPE_CNV)
                return -EIO;

        if (iocb->ki_flags & IOCB_NOWAIT) {
                if (!inode_trylock(inode))
                        return -EAGAIN;
        } else {
                inode_lock(inode);
        }

        ret = zonefs_write_checks(iocb, from);
        if (ret <= 0)
                goto inode_unlock;

        ret = iomap_file_buffered_write(iocb, from, &zonefs_iomap_ops);
        if (ret > 0)
                iocb->ki_pos += ret;
        else if (ret == -EIO)
                zonefs_io_error(inode, true);

inode_unlock:
        inode_unlock(inode);
        if (ret > 0)
                ret = generic_write_sync(iocb, ret);

        return ret;
}

static ssize_t zonefs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
        struct inode *inode = file_inode(iocb->ki_filp);

        if (unlikely(IS_IMMUTABLE(inode)))
                return -EPERM;

        if (sb_rdonly(inode->i_sb))
                return -EROFS;

        /* Write operations beyond the zone size are not allowed */
        if (iocb->ki_pos >= ZONEFS_I(inode)->i_max_size)
                return -EFBIG;

        if (iocb->ki_flags & IOCB_DIRECT) {
                ssize_t ret = zonefs_file_dio_write(iocb, from);
                if (ret != -ENOTBLK)
                        return ret;
        }

        return zonefs_file_buffered_write(iocb, from);
}

static int zonefs_file_read_dio_end_io(struct kiocb *iocb, ssize_t size,
                                       int error, unsigned int flags)
{
        if (error) {
                zonefs_io_error(file_inode(iocb->ki_filp), false);
                return error;
        }

        return 0;
}

static const struct iomap_dio_ops zonefs_read_dio_ops = {
        .end_io                 = zonefs_file_read_dio_end_io,
};

static ssize_t zonefs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
        struct inode *inode = file_inode(iocb->ki_filp);
        struct zonefs_inode_info *zi = ZONEFS_I(inode);
        struct super_block *sb = inode->i_sb;
        loff_t isize;
        ssize_t ret;

        /* Offline zones cannot be read */
        if (unlikely(IS_IMMUTABLE(inode) && !(inode->i_mode & 0777)))
                return -EPERM;

        if (iocb->ki_pos >= zi->i_max_size)
                return 0;

        if (iocb->ki_flags & IOCB_NOWAIT) {
                if (!inode_trylock_shared(inode))
                        return -EAGAIN;
        } else {
                inode_lock_shared(inode);
        }

        /* Limit read operations to written data */
        mutex_lock(&zi->i_truncate_mutex);
        isize = i_size_read(inode);
        if (iocb->ki_pos >= isize) {
                mutex_unlock(&zi->i_truncate_mutex);
                ret = 0;
                goto inode_unlock;
        }
        iov_iter_truncate(to, isize - iocb->ki_pos);
        mutex_unlock(&zi->i_truncate_mutex);

        if (iocb->ki_flags & IOCB_DIRECT) {
                size_t count = iov_iter_count(to);

                if ((iocb->ki_pos | count) & (sb->s_blocksize - 1)) {
                        ret = -EINVAL;
                        goto inode_unlock;
                }
                file_accessed(iocb->ki_filp);
                ret = iomap_dio_rw(iocb, to, &zonefs_iomap_ops,
                                   &zonefs_read_dio_ops, 0);
        } else {
                ret = generic_file_read_iter(iocb, to);
                if (ret == -EIO)
                        zonefs_io_error(inode, false);
        }

inode_unlock:
        inode_unlock_shared(inode);

        return ret;
}

static inline bool zonefs_file_use_exp_open(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;

        if (!(file->f_mode & FMODE_WRITE))
                return false;

        return true;
}

static int zonefs_open_zone(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) {
                if (atomic_inc_return(&sbi->s_open_zones) > sbi->s_max_open_zones) {
                        atomic_dec(&sbi->s_open_zones);
                        ret = -EBUSY;
                        goto unlock;
                }

                if (i_size_read(inode) < zi->i_max_size) {
                        ret = zonefs_zone_mgmt(inode, REQ_OP_ZONE_OPEN);
                        if (ret) {
                                atomic_dec(&sbi->s_open_zones);
                                goto unlock;
                        }
                        zi->i_flags |= ZONEFS_ZONE_OPEN;
                }
        }

        zi->i_wr_refcnt++;

unlock:
        mutex_unlock(&zi->i_truncate_mutex);

        return ret;
}

static int zonefs_file_open(struct inode *inode, struct file *file)
{
        int ret;

        ret = generic_file_open(inode, file);
        if (ret)
                return ret;

        if (zonefs_file_use_exp_open(inode, file))
                return zonefs_open_zone(inode);

        return 0;
}

static void zonefs_close_zone(struct inode *inode)
{
        struct zonefs_inode_info *zi = ZONEFS_I(inode);
        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;

                ret = zonefs_zone_mgmt(inode, REQ_OP_ZONE_CLOSE);
                if (ret) {
                        __zonefs_io_error(inode, false);
                        /*
                         * Leaving zones explicitly open may lead to a state
                         * where most zones cannot be written (zone resources
                         * exhausted). So take preventive action by remounting
                         * read-only.
                         */
                        if (zi->i_flags & ZONEFS_ZONE_OPEN &&
                            !(sb->s_flags & SB_RDONLY)) {
                                zonefs_warn(sb, "closing zone failed, remounting filesystem read-only\n");
                                sb->s_flags |= SB_RDONLY;
                        }
                }
                zi->i_flags &= ~ZONEFS_ZONE_OPEN;
dec:
                atomic_dec(&sbi->s_open_zones);
        }
        mutex_unlock(&zi->i_truncate_mutex);
}

static int zonefs_file_release(struct inode *inode, struct file *file)
{
        /*
         * If we explicitly open a zone we must close it again as well, but the
         * zone management operation can fail (either due to an IO error or as
         * 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);

        return 0;
}

static const struct file_operations zonefs_file_operations = {
        .open           = zonefs_file_open,
        .release        = zonefs_file_release,
        .fsync          = zonefs_file_fsync,
        .mmap           = zonefs_file_mmap,
        .llseek         = zonefs_file_llseek,
        .read_iter      = zonefs_file_read_iter,
        .write_iter     = zonefs_file_write_iter,
        .splice_read    = generic_file_splice_read,
        .splice_write   = iter_file_splice_write,
        .iopoll         = iomap_dio_iopoll,
};

static struct kmem_cache *zonefs_inode_cachep;

static struct inode *zonefs_alloc_inode(struct super_block *sb)
{
        struct zonefs_inode_info *zi;

        zi = kmem_cache_alloc(zonefs_inode_cachep, GFP_KERNEL);
        if (!zi)
                return NULL;

        inode_init_once(&zi->i_vnode);
        mutex_init(&zi->i_truncate_mutex);
        init_rwsem(&zi->i_mmap_sem);
        zi->i_wr_refcnt = 0;

        return &zi->i_vnode;
}

static void zonefs_free_inode(struct inode *inode)
{
        kmem_cache_free(zonefs_inode_cachep, ZONEFS_I(inode));
}

/*
 * File system stat.
 */
static int zonefs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
        struct super_block *sb = dentry->d_sb;
        struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
        enum zonefs_ztype t;

        buf->f_type = ZONEFS_MAGIC;
        buf->f_bsize = sb->s_blocksize;
        buf->f_namelen = ZONEFS_NAME_MAX;

        spin_lock(&sbi->s_lock);

        buf->f_blocks = sbi->s_blocks;
        if (WARN_ON(sbi->s_used_blocks > sbi->s_blocks))
                buf->f_bfree = 0;
        else
                buf->f_bfree = buf->f_blocks - sbi->s_used_blocks;
        buf->f_bavail = buf->f_bfree;

        for (t = 0; t < ZONEFS_ZTYPE_MAX; t++) {
                if (sbi->s_nr_files[t])
                        buf->f_files += sbi->s_nr_files[t] + 1;
        }
        buf->f_ffree = 0;

        spin_unlock(&sbi->s_lock);

        buf->f_fsid = uuid_to_fsid(sbi->s_uuid.b);

        return 0;
}

enum {
        Opt_errors_ro, Opt_errors_zro, Opt_errors_zol, Opt_errors_repair,
        Opt_explicit_open, Opt_err,
};

static const match_table_t tokens = {
        { Opt_errors_ro,        "errors=remount-ro"},
        { Opt_errors_zro,       "errors=zone-ro"},
        { Opt_errors_zol,       "errors=zone-offline"},
        { Opt_errors_repair,    "errors=repair"},
        { Opt_explicit_open,    "explicit-open" },
        { Opt_err,              NULL}
};

static int zonefs_parse_options(struct super_block *sb, char *options)
{
        struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
        substring_t args[MAX_OPT_ARGS];
        char *p;

        if (!options)
                return 0;

        while ((p = strsep(&options, ",")) != NULL) {
                int token;

                if (!*p)
                        continue;

                token = match_token(p, tokens, args);
                switch (token) {
                case Opt_errors_ro:
                        sbi->s_mount_opts &= ~ZONEFS_MNTOPT_ERRORS_MASK;
                        sbi->s_mount_opts |= ZONEFS_MNTOPT_ERRORS_RO;
                        break;
                case Opt_errors_zro:
                        sbi->s_mount_opts &= ~ZONEFS_MNTOPT_ERRORS_MASK;
                        sbi->s_mount_opts |= ZONEFS_MNTOPT_ERRORS_ZRO;
                        break;
                case Opt_errors_zol:
                        sbi->s_mount_opts &= ~ZONEFS_MNTOPT_ERRORS_MASK;
                        sbi->s_mount_opts |= ZONEFS_MNTOPT_ERRORS_ZOL;
                        break;
                case Opt_errors_repair:
                        sbi->s_mount_opts &= ~ZONEFS_MNTOPT_ERRORS_MASK;
                        sbi->s_mount_opts |= ZONEFS_MNTOPT_ERRORS_REPAIR;
                        break;
                case Opt_explicit_open:
                        sbi->s_mount_opts |= ZONEFS_MNTOPT_EXPLICIT_OPEN;
                        break;
                default:
                        return -EINVAL;
                }
        }

        return 0;
}

static int zonefs_show_options(struct seq_file *seq, struct dentry *root)
{
        struct zonefs_sb_info *sbi = ZONEFS_SB(root->d_sb);

        if (sbi->s_mount_opts & ZONEFS_MNTOPT_ERRORS_RO)
                seq_puts(seq, ",errors=remount-ro");
        if (sbi->s_mount_opts & ZONEFS_MNTOPT_ERRORS_ZRO)
                seq_puts(seq, ",errors=zone-ro");
        if (sbi->s_mount_opts & ZONEFS_MNTOPT_ERRORS_ZOL)
                seq_puts(seq, ",errors=zone-offline");
        if (sbi->s_mount_opts & ZONEFS_MNTOPT_ERRORS_REPAIR)
                seq_puts(seq, ",errors=repair");

        return 0;
}

static int zonefs_remount(struct super_block *sb, int *flags, char *data)
{
        sync_filesystem(sb);

        return zonefs_parse_options(sb, data);
}

static const struct super_operations zonefs_sops = {
        .alloc_inode    = zonefs_alloc_inode,
        .free_inode     = zonefs_free_inode,
        .statfs         = zonefs_statfs,
        .remount_fs     = zonefs_remount,
        .show_options   = zonefs_show_options,
};

static const struct inode_operations zonefs_dir_inode_operations = {
        .lookup         = simple_lookup,
        .setattr        = zonefs_inode_setattr,
};

static void zonefs_init_dir_inode(struct inode *parent, struct inode *inode,
                                  enum zonefs_ztype type)
{
        struct super_block *sb = parent->i_sb;

        inode->i_ino = blkdev_nr_zones(sb->s_bdev->bd_disk) + type + 1;
        inode_init_owner(&init_user_ns, inode, parent, S_IFDIR | 0555);
        inode->i_op = &zonefs_dir_inode_operations;
        inode->i_fop = &simple_dir_operations;
        set_nlink(inode, 2);
        inc_nlink(parent);
}

static void zonefs_init_file_inode(struct inode *inode, struct blk_zone *zone,
                                   enum zonefs_ztype type)
{
        struct super_block *sb = inode->i_sb;
        struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
        struct zonefs_inode_info *zi = ZONEFS_I(inode);

        inode->i_ino = zone->start >> sbi->s_zone_sectors_shift;
        inode->i_mode = S_IFREG | sbi->s_perm;

        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->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 = zi->i_max_size >> SECTOR_SHIFT;

        inode->i_op = &zonefs_file_inode_operations;
        inode->i_fop = &zonefs_file_operations;
        inode->i_mapping->a_ops = &zonefs_file_aops;

        sb->s_maxbytes = max(zi->i_max_size, sb->s_maxbytes);
        sbi->s_blocks += zi->i_max_size >> sb->s_blocksize_bits;
        sbi->s_used_blocks += zi->i_wpoffset >> sb->s_blocksize_bits;
}

static struct dentry *zonefs_create_inode(struct dentry *parent,
                                        const char *name, struct blk_zone *zone,
                                        enum zonefs_ztype type)
{
        struct inode *dir = d_inode(parent);
        struct dentry *dentry;
        struct inode *inode;

        dentry = d_alloc_name(parent, name);
        if (!dentry)
                return NULL;

        inode = new_inode(parent->d_sb);
        if (!inode)
                goto dput;

        inode->i_ctime = inode->i_mtime = inode->i_atime = dir->i_ctime;
        if (zone)
                zonefs_init_file_inode(inode, zone, type);
        else
                zonefs_init_dir_inode(dir, inode, type);
        d_add(dentry, inode);
        dir->i_size++;

        return dentry;

dput:
        dput(dentry);

        return NULL;
}

struct zonefs_zone_data {
        struct super_block      *sb;
        unsigned int            nr_zones[ZONEFS_ZTYPE_MAX];
        struct blk_zone         *zones;
};

/*
 * Create a zone group and populate it with zone files.
 */
static int zonefs_create_zgroup(struct zonefs_zone_data *zd,
                                enum zonefs_ztype type)
{
        struct super_block *sb = zd->sb;
        struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
        struct blk_zone *zone, *next, *end;
        const char *zgroup_name;
        char *file_name;
        struct dentry *dir;
        unsigned int n = 0;
        int ret;

        /* If the group is empty, there is nothing to do */
        if (!zd->nr_zones[type])
                return 0;

        file_name = kmalloc(ZONEFS_NAME_MAX, GFP_KERNEL);
        if (!file_name)
                return -ENOMEM;

        if (type == ZONEFS_ZTYPE_CNV)
                zgroup_name = "cnv";
        else
                zgroup_name = "seq";

        dir = zonefs_create_inode(sb->s_root, zgroup_name, NULL, type);
        if (!dir) {
                ret = -ENOMEM;
                goto free;
        }

        /*
         * The first zone contains the super block: skip it.
         */
        end = zd->zones + blkdev_nr_zones(sb->s_bdev->bd_disk);
        for (zone = &zd->zones[1]; zone < end; zone = next) {

                next = zone + 1;
                if (zonefs_zone_type(zone) != type)
                        continue;

                /*
                 * For conventional zones, contiguous zones can be aggregated
                 * together to form larger files. Note that this overwrites the
                 * length of the first zone of the set of contiguous zones
                 * aggregated together. If one offline or read-only zone is
                 * found, assume that all zones aggregated have the same
                 * condition.
                 */
                if (type == ZONEFS_ZTYPE_CNV &&
                    (sbi->s_features & ZONEFS_F_AGGRCNV)) {
                        for (; next < end; next++) {
                                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;
                        }
                }

                /*
                 * Use the file number within its group as file name.
                 */
                snprintf(file_name, ZONEFS_NAME_MAX - 1, "%u", n);
                if (!zonefs_create_inode(dir, file_name, zone, type)) {
                        ret = -ENOMEM;
                        goto free;
                }

                n++;
        }

        zonefs_info(sb, "Zone group \"%s\" has %u file%s\n",
                    zgroup_name, n, n > 1 ? "s" : "");

        sbi->s_nr_files[type] = n;
        ret = 0;

free:
        kfree(file_name);

        return ret;
}

static int zonefs_get_zone_info_cb(struct blk_zone *zone, unsigned int idx,
                                   void *data)
{
        struct zonefs_zone_data *zd = data;

        /*
         * Count the number of usable zones: the first zone at index 0 contains
         * the super block and is ignored.
         */
        switch (zone->type) {
        case BLK_ZONE_TYPE_CONVENTIONAL:
                zone->wp = zone->start + zone->len;
                if (idx)
                        zd->nr_zones[ZONEFS_ZTYPE_CNV]++;
                break;
        case BLK_ZONE_TYPE_SEQWRITE_REQ:
        case BLK_ZONE_TYPE_SEQWRITE_PREF:
                if (idx)
                        zd->nr_zones[ZONEFS_ZTYPE_SEQ]++;
                break;
        default:
                zonefs_err(zd->sb, "Unsupported zone type 0x%x\n",
                           zone->type);
                return -EIO;
        }

        memcpy(&zd->zones[idx], zone, sizeof(struct blk_zone));

        return 0;
}

static int zonefs_get_zone_info(struct zonefs_zone_data *zd)
{
        struct block_device *bdev = zd->sb->s_bdev;
        int ret;

        zd->zones = kvcalloc(blkdev_nr_zones(bdev->bd_disk),
                             sizeof(struct blk_zone), GFP_KERNEL);
        if (!zd->zones)
                return -ENOMEM;

        /* Get zones information from the device */
        ret = blkdev_report_zones(bdev, 0, BLK_ALL_ZONES,
                                  zonefs_get_zone_info_cb, zd);
        if (ret < 0) {
                zonefs_err(zd->sb, "Zone report failed %d\n", ret);
                return ret;
        }

        if (ret != blkdev_nr_zones(bdev->bd_disk)) {
                zonefs_err(zd->sb, "Invalid zone report (%d/%u zones)\n",
                           ret, blkdev_nr_zones(bdev->bd_disk));
                return -EIO;
        }

        return 0;
}

static inline void zonefs_cleanup_zone_info(struct zonefs_zone_data *zd)
{
        kvfree(zd->zones);
}

/*
 * Read super block information from the device.
 */
static int zonefs_read_super(struct super_block *sb)
{
        struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
        struct zonefs_super *super;
        u32 crc, stored_crc;
        struct page *page;
        struct bio_vec bio_vec;
        struct bio bio;
        int ret;

        page = alloc_page(GFP_KERNEL);
        if (!page)
                return -ENOMEM;

        bio_init(&bio, &bio_vec, 1);
        bio.bi_iter.bi_sector = 0;
        bio.bi_opf = REQ_OP_READ;
        bio_set_dev(&bio, sb->s_bdev);
        bio_add_page(&bio, page, PAGE_SIZE, 0);

        ret = submit_bio_wait(&bio);
        if (ret)
                goto free_page;

        super = kmap(page);

        ret = -EINVAL;
        if (le32_to_cpu(super->s_magic) != ZONEFS_MAGIC)
                goto unmap;

        stored_crc = le32_to_cpu(super->s_crc);
        super->s_crc = 0;
        crc = crc32(~0U, (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);
                goto unmap;
        }

        sbi->s_features = le64_to_cpu(super->s_features);
        if (sbi->s_features & ~ZONEFS_F_DEFINED_FEATURES) {
                zonefs_err(sb, "Unknown features set 0x%llx\n",
                           sbi->s_features);
                goto unmap;
        }

        if (sbi->s_features & 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 unmap;
                }
        }

        if (sbi->s_features & 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 unmap;
                }
        }

        if (sbi->s_features & ZONEFS_F_PERM)
                sbi->s_perm = le32_to_cpu(super->s_perm);

        if (memchr_inv(super->s_reserved, 0, sizeof(super->s_reserved))) {
                zonefs_err(sb, "Reserved area is being used\n");
                goto unmap;
        }

        import_uuid(&sbi->s_uuid, super->s_uuid);
        ret = 0;

unmap:
        kunmap(page);
free_page:
        __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 and
 * format options.
 */
static int zonefs_fill_super(struct super_block *sb, void *data, int silent)
{
        struct zonefs_zone_data zd;
        struct zonefs_sb_info *sbi;
        struct inode *inode;
        enum zonefs_ztype t;
        int ret;

        if (!bdev_is_zoned(sb->s_bdev)) {
                zonefs_err(sb, "Not a zoned block device\n");
                return -EINVAL;
        }

        /*
         * Initialize super block information: the maximum file size is updated
         * when the zone files are created so that the format option
         * ZONEFS_F_AGGRCNV which increases the maximum file size of a file
         * beyond the zone size is taken into account.
         */
        sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
        if (!sbi)
                return -ENOMEM;

        spin_lock_init(&sbi->s_lock);
        sb->s_fs_info = sbi;
        sb->s_magic = ZONEFS_MAGIC;
        sb->s_maxbytes = 0;
        sb->s_op = &zonefs_sops;
        sb->s_time_gran = 1;

        /*
         * The block size is set to the device zone write granularity to ensure
         * that write operations are always aligned according to the device
         * interface constraints.
         */
        sb_set_blocksize(sb, bdev_zone_write_granularity(sb->s_bdev));
        sbi->s_zone_sectors_shift = ilog2(bdev_zone_sectors(sb->s_bdev));
        sbi->s_uid = GLOBAL_ROOT_UID;
        sbi->s_gid = GLOBAL_ROOT_GID;
        sbi->s_perm = 0640;
        sbi->s_mount_opts = ZONEFS_MNTOPT_ERRORS_RO;
        sbi->s_max_open_zones = bdev_max_open_zones(sb->s_bdev);
        atomic_set(&sbi->s_open_zones, 0);
        if (!sbi->s_max_open_zones &&
            sbi->s_mount_opts & ZONEFS_MNTOPT_EXPLICIT_OPEN) {
                zonefs_info(sb, "No open zones limit. Ignoring explicit_open mount option\n");
                sbi->s_mount_opts &= ~ZONEFS_MNTOPT_EXPLICIT_OPEN;
        }

        ret = zonefs_read_super(sb);
        if (ret)
                return ret;

        ret = zonefs_parse_options(sb, data);
        if (ret)
                return ret;

        memset(&zd, 0, sizeof(struct zonefs_zone_data));
        zd.sb = sb;
        ret = zonefs_get_zone_info(&zd);
        if (ret)
                goto cleanup;

        zonefs_info(sb, "Mounting %u zones",
                    blkdev_nr_zones(sb->s_bdev->bd_disk));

        /* Create root directory inode */
        ret = -ENOMEM;
        inode = new_inode(sb);
        if (!inode)
                goto cleanup;

        inode->i_ino = blkdev_nr_zones(sb->s_bdev->bd_disk);
        inode->i_mode = S_IFDIR | 0555;
        inode->i_ctime = inode->i_mtime = inode->i_atime = current_time(inode);
        inode->i_op = &zonefs_dir_inode_operations;
        inode->i_fop = &simple_dir_operations;
        set_nlink(inode, 2);

        sb->s_root = d_make_root(inode);
        if (!sb->s_root)
                goto cleanup;

        /* Create and populate files in zone groups directories */
        for (t = 0; t < ZONEFS_ZTYPE_MAX; t++) {
                ret = zonefs_create_zgroup(&zd, t);
                if (ret)
                        break;
        }

cleanup:
        zonefs_cleanup_zone_info(&zd);

        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);

        if (sb->s_root)
                d_genocide(sb->s_root);
        kill_block_super(sb);
        kfree(sbi);
}

/*
 * 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);