FreeBSD/Linux Kernel Cross Reference
sys/contrib/openzfs/module/os/linux/zfs/vdev_disk.c

     /*
      * CDDL HEADER START
      *
      * The contents of this file are subject to the terms of the
      * Common Development and Distribution License (the "License").
      * You may not use this file except in compliance with the License.
      *
      * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      * or https://opensource.org/licenses/CDDL-1.0.
     * See the License for the specific language governing permissions
     * and limitations under the License.
     *
     * When distributing Covered Code, include this CDDL HEADER in each
     * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     * If applicable, add the following below this CDDL HEADER, with the
     * fields enclosed by brackets "[]" replaced with your own identifying
     * information: Portions Copyright [yyyy] [name of copyright owner]
     *
     * CDDL HEADER END
     */
    /*
     * Copyright (C) 2008-2010 Lawrence Livermore National Security, LLC.
     * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
     * Rewritten for Linux by Brian Behlendorf <behlendorf1@llnl.gov>.
     * LLNL-CODE-403049.
     * Copyright (c) 2012, 2019 by Delphix. All rights reserved.
     */
    
    #include <sys/zfs_context.h>
    #include <sys/spa_impl.h>
    #include <sys/vdev_disk.h>
    #include <sys/vdev_impl.h>
    #include <sys/vdev_trim.h>
    #include <sys/abd.h>
    #include <sys/fs/zfs.h>
    #include <sys/zio.h>
    #include <linux/blkpg.h>
    #include <linux/msdos_fs.h>
    #include <linux/vfs_compat.h>
    #ifdef HAVE_LINUX_BLK_CGROUP_HEADER
    #include <linux/blk-cgroup.h>
    #endif
    
    typedef struct vdev_disk {
            struct block_device             *vd_bdev;
            krwlock_t                       vd_lock;
    } vdev_disk_t;
    
    /*
     * Unique identifier for the exclusive vdev holder.
     */
    static void *zfs_vdev_holder = VDEV_HOLDER;
    
    /*
     * Wait up to zfs_vdev_open_timeout_ms milliseconds before determining the
     * device is missing. The missing path may be transient since the links
     * can be briefly removed and recreated in response to udev events.
     */
    static uint_t zfs_vdev_open_timeout_ms = 1000;
    
    /*
     * Size of the "reserved" partition, in blocks.
     */
    #define EFI_MIN_RESV_SIZE       (16 * 1024)
    
    /*
     * Virtual device vector for disks.
     */
    typedef struct dio_request {
            zio_t                   *dr_zio;        /* Parent ZIO */
            atomic_t                dr_ref;         /* References */
            int                     dr_error;       /* Bio error */
            int                     dr_bio_count;   /* Count of bio's */
            struct bio              *dr_bio[];      /* Attached bio's */
    } dio_request_t;
    
    /*
     * BIO request failfast mask.
     */
    
    static unsigned int zfs_vdev_failfast_mask = 1;
    
    static fmode_t
    vdev_bdev_mode(spa_mode_t spa_mode)
    {
            fmode_t mode = 0;
    
            if (spa_mode & SPA_MODE_READ)
                    mode |= FMODE_READ;
    
            if (spa_mode & SPA_MODE_WRITE)
                    mode |= FMODE_WRITE;
    
            return (mode);
    }
    
    /*
     * Returns the usable capacity (in bytes) for the partition or disk.
     */
   static uint64_t
   bdev_capacity(struct block_device *bdev)
   {
           return (i_size_read(bdev->bd_inode));
   }
   
   #if !defined(HAVE_BDEV_WHOLE)
   static inline struct block_device *
   bdev_whole(struct block_device *bdev)
   {
           return (bdev->bd_contains);
   }
   #endif
   
   #if defined(HAVE_BDEVNAME)
   #define vdev_bdevname(bdev, name)       bdevname(bdev, name)
   #else
   static inline void
   vdev_bdevname(struct block_device *bdev, char *name)
   {
           snprintf(name, BDEVNAME_SIZE, "%pg", bdev);
   }
   #endif
   
   /*
    * Returns the maximum expansion capacity of the block device (in bytes).
    *
    * It is possible to expand a vdev when it has been created as a wholedisk
    * and the containing block device has increased in capacity.  Or when the
    * partition containing the pool has been manually increased in size.
    *
    * This function is only responsible for calculating the potential expansion
    * size so it can be reported by 'zpool list'.  The efi_use_whole_disk() is
    * responsible for verifying the expected partition layout in the wholedisk
    * case, and updating the partition table if appropriate.  Once the partition
    * size has been increased the additional capacity will be visible using
    * bdev_capacity().
    *
    * The returned maximum expansion capacity is always expected to be larger, or
    * at the very least equal, to its usable capacity to prevent overestimating
    * the pool expandsize.
    */
   static uint64_t
   bdev_max_capacity(struct block_device *bdev, uint64_t wholedisk)
   {
           uint64_t psize;
           int64_t available;
   
           if (wholedisk && bdev != bdev_whole(bdev)) {
                   /*
                    * When reporting maximum expansion capacity for a wholedisk
                    * deduct any capacity which is expected to be lost due to
                    * alignment restrictions.  Over reporting this value isn't
                    * harmful and would only result in slightly less capacity
                    * than expected post expansion.
                    * The estimated available space may be slightly smaller than
                    * bdev_capacity() for devices where the number of sectors is
                    * not a multiple of the alignment size and the partition layout
                    * is keeping less than PARTITION_END_ALIGNMENT bytes after the
                    * "reserved" EFI partition: in such cases return the device
                    * usable capacity.
                    */
                   available = i_size_read(bdev_whole(bdev)->bd_inode) -
                       ((EFI_MIN_RESV_SIZE + NEW_START_BLOCK +
                       PARTITION_END_ALIGNMENT) << SECTOR_BITS);
                   psize = MAX(available, bdev_capacity(bdev));
           } else {
                   psize = bdev_capacity(bdev);
           }
   
           return (psize);
   }
   
   static void
   vdev_disk_error(zio_t *zio)
   {
           /*
            * This function can be called in interrupt context, for instance while
            * handling IRQs coming from a misbehaving disk device; use printk()
            * which is safe from any context.
            */
           printk(KERN_WARNING "zio pool=%s vdev=%s error=%d type=%d "
               "offset=%llu size=%llu flags=%llu\n", spa_name(zio->io_spa),
               zio->io_vd->vdev_path, zio->io_error, zio->io_type,
               (u_longlong_t)zio->io_offset, (u_longlong_t)zio->io_size,
               zio->io_flags);
   }
   
   static void
   vdev_disk_kobj_evt_post(vdev_t *v)
   {
           vdev_disk_t *vd = v->vdev_tsd;
           if (vd && vd->vd_bdev) {
                   spl_signal_kobj_evt(vd->vd_bdev);
           } else {
                   vdev_dbgmsg(v, "vdev_disk_t is NULL for VDEV:%s\n",
                       v->vdev_path);
           }
   }
   
   static int
   vdev_disk_open(vdev_t *v, uint64_t *psize, uint64_t *max_psize,
       uint64_t *logical_ashift, uint64_t *physical_ashift)
   {
           struct block_device *bdev;
           fmode_t mode = vdev_bdev_mode(spa_mode(v->vdev_spa));
           hrtime_t timeout = MSEC2NSEC(zfs_vdev_open_timeout_ms);
           vdev_disk_t *vd;
   
           /* Must have a pathname and it must be absolute. */
           if (v->vdev_path == NULL || v->vdev_path[0] != '/') {
                   v->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
                   vdev_dbgmsg(v, "invalid vdev_path");
                   return (SET_ERROR(EINVAL));
           }
   
           /*
            * Reopen the device if it is currently open.  When expanding a
            * partition force re-scanning the partition table if userland
            * did not take care of this already. We need to do this while closed
            * in order to get an accurate updated block device size.  Then
            * since udev may need to recreate the device links increase the
            * open retry timeout before reporting the device as unavailable.
            */
           vd = v->vdev_tsd;
           if (vd) {
                   char disk_name[BDEVNAME_SIZE + 6] = "/dev/";
                   boolean_t reread_part = B_FALSE;
   
                   rw_enter(&vd->vd_lock, RW_WRITER);
                   bdev = vd->vd_bdev;
                   vd->vd_bdev = NULL;
   
                   if (bdev) {
                           if (v->vdev_expanding && bdev != bdev_whole(bdev)) {
                                   vdev_bdevname(bdev_whole(bdev), disk_name + 5);
                                   /*
                                    * If userland has BLKPG_RESIZE_PARTITION,
                                    * then it should have updated the partition
                                    * table already. We can detect this by
                                    * comparing our current physical size
                                    * with that of the device. If they are
                                    * the same, then we must not have
                                    * BLKPG_RESIZE_PARTITION or it failed to
                                    * update the partition table online. We
                                    * fallback to rescanning the partition
                                    * table from the kernel below. However,
                                    * if the capacity already reflects the
                                    * updated partition, then we skip
                                    * rescanning the partition table here.
                                    */
                                   if (v->vdev_psize == bdev_capacity(bdev))
                                           reread_part = B_TRUE;
                           }
   
                           blkdev_put(bdev, mode | FMODE_EXCL);
                   }
   
                   if (reread_part) {
                           bdev = blkdev_get_by_path(disk_name, mode | FMODE_EXCL,
                               zfs_vdev_holder);
                           if (!IS_ERR(bdev)) {
                                   int error = vdev_bdev_reread_part(bdev);
                                   blkdev_put(bdev, mode | FMODE_EXCL);
                                   if (error == 0) {
                                           timeout = MSEC2NSEC(
                                               zfs_vdev_open_timeout_ms * 2);
                                   }
                           }
                   }
           } else {
                   vd = kmem_zalloc(sizeof (vdev_disk_t), KM_SLEEP);
   
                   rw_init(&vd->vd_lock, NULL, RW_DEFAULT, NULL);
                   rw_enter(&vd->vd_lock, RW_WRITER);
           }
   
           /*
            * Devices are always opened by the path provided at configuration
            * time.  This means that if the provided path is a udev by-id path
            * then drives may be re-cabled without an issue.  If the provided
            * path is a udev by-path path, then the physical location information
            * will be preserved.  This can be critical for more complicated
            * configurations where drives are located in specific physical
            * locations to maximize the systems tolerance to component failure.
            *
            * Alternatively, you can provide your own udev rule to flexibly map
            * the drives as you see fit.  It is not advised that you use the
            * /dev/[hd]d devices which may be reordered due to probing order.
            * Devices in the wrong locations will be detected by the higher
            * level vdev validation.
            *
            * The specified paths may be briefly removed and recreated in
            * response to udev events.  This should be exceptionally unlikely
            * because the zpool command makes every effort to verify these paths
            * have already settled prior to reaching this point.  Therefore,
            * a ENOENT failure at this point is highly likely to be transient
            * and it is reasonable to sleep and retry before giving up.  In
            * practice delays have been observed to be on the order of 100ms.
            *
            * When ERESTARTSYS is returned it indicates the block device is
            * a zvol which could not be opened due to the deadlock detection
            * logic in zvol_open().  Extend the timeout and retry the open
            * subsequent attempts are expected to eventually succeed.
            */
           hrtime_t start = gethrtime();
           bdev = ERR_PTR(-ENXIO);
           while (IS_ERR(bdev) && ((gethrtime() - start) < timeout)) {
                   bdev = blkdev_get_by_path(v->vdev_path, mode | FMODE_EXCL,
                       zfs_vdev_holder);
                   if (unlikely(PTR_ERR(bdev) == -ENOENT)) {
                           /*
                            * There is no point of waiting since device is removed
                            * explicitly
                            */
                           if (v->vdev_removed)
                                   break;
   
                           schedule_timeout(MSEC_TO_TICK(10));
                   } else if (unlikely(PTR_ERR(bdev) == -ERESTARTSYS)) {
                           timeout = MSEC2NSEC(zfs_vdev_open_timeout_ms * 10);
                           continue;
                   } else if (IS_ERR(bdev)) {
                           break;
                   }
           }
   
           if (IS_ERR(bdev)) {
                   int error = -PTR_ERR(bdev);
                   vdev_dbgmsg(v, "open error=%d timeout=%llu/%llu", error,
                       (u_longlong_t)(gethrtime() - start),
                       (u_longlong_t)timeout);
                   vd->vd_bdev = NULL;
                   v->vdev_tsd = vd;
                   rw_exit(&vd->vd_lock);
                   return (SET_ERROR(error));
           } else {
                   vd->vd_bdev = bdev;
                   v->vdev_tsd = vd;
                   rw_exit(&vd->vd_lock);
           }
   
           /*  Determine the physical block size */
           int physical_block_size = bdev_physical_block_size(vd->vd_bdev);
   
           /*  Determine the logical block size */
           int logical_block_size = bdev_logical_block_size(vd->vd_bdev);
   
           /* Clear the nowritecache bit, causes vdev_reopen() to try again. */
           v->vdev_nowritecache = B_FALSE;
   
           /* Set when device reports it supports TRIM. */
           v->vdev_has_trim = bdev_discard_supported(vd->vd_bdev);
   
           /* Set when device reports it supports secure TRIM. */
           v->vdev_has_securetrim = bdev_secure_discard_supported(vd->vd_bdev);
   
           /* Inform the ZIO pipeline that we are non-rotational */
           v->vdev_nonrot = blk_queue_nonrot(bdev_get_queue(vd->vd_bdev));
   
           /* Physical volume size in bytes for the partition */
           *psize = bdev_capacity(vd->vd_bdev);
   
           /* Physical volume size in bytes including possible expansion space */
           *max_psize = bdev_max_capacity(vd->vd_bdev, v->vdev_wholedisk);
   
           /* Based on the minimum sector size set the block size */
           *physical_ashift = highbit64(MAX(physical_block_size,
               SPA_MINBLOCKSIZE)) - 1;
   
           *logical_ashift = highbit64(MAX(logical_block_size,
               SPA_MINBLOCKSIZE)) - 1;
   
           return (0);
   }
   
   static void
   vdev_disk_close(vdev_t *v)
   {
           vdev_disk_t *vd = v->vdev_tsd;
   
           if (v->vdev_reopening || vd == NULL)
                   return;
   
           if (vd->vd_bdev != NULL) {
                   blkdev_put(vd->vd_bdev,
                       vdev_bdev_mode(spa_mode(v->vdev_spa)) | FMODE_EXCL);
           }
   
           rw_destroy(&vd->vd_lock);
           kmem_free(vd, sizeof (vdev_disk_t));
           v->vdev_tsd = NULL;
   }
   
   static dio_request_t *
   vdev_disk_dio_alloc(int bio_count)
   {
           dio_request_t *dr = kmem_zalloc(sizeof (dio_request_t) +
               sizeof (struct bio *) * bio_count, KM_SLEEP);
           atomic_set(&dr->dr_ref, 0);
           dr->dr_bio_count = bio_count;
           dr->dr_error = 0;
   
           for (int i = 0; i < dr->dr_bio_count; i++)
                   dr->dr_bio[i] = NULL;
   
           return (dr);
   }
   
   static void
   vdev_disk_dio_free(dio_request_t *dr)
   {
           int i;
   
           for (i = 0; i < dr->dr_bio_count; i++)
                   if (dr->dr_bio[i])
                           bio_put(dr->dr_bio[i]);
   
           kmem_free(dr, sizeof (dio_request_t) +
               sizeof (struct bio *) * dr->dr_bio_count);
   }
   
   static void
   vdev_disk_dio_get(dio_request_t *dr)
   {
           atomic_inc(&dr->dr_ref);
   }
   
   static void
   vdev_disk_dio_put(dio_request_t *dr)
   {
           int rc = atomic_dec_return(&dr->dr_ref);
   
           /*
            * Free the dio_request when the last reference is dropped and
            * ensure zio_interpret is called only once with the correct zio
            */
           if (rc == 0) {
                   zio_t *zio = dr->dr_zio;
                   int error = dr->dr_error;
   
                   vdev_disk_dio_free(dr);
   
                   if (zio) {
                           zio->io_error = error;
                           ASSERT3S(zio->io_error, >=, 0);
                           if (zio->io_error)
                                   vdev_disk_error(zio);
   
                           zio_delay_interrupt(zio);
                   }
           }
   }
   
   BIO_END_IO_PROTO(vdev_disk_physio_completion, bio, error)
   {
           dio_request_t *dr = bio->bi_private;
   
           if (dr->dr_error == 0) {
   #ifdef HAVE_1ARG_BIO_END_IO_T
                   dr->dr_error = BIO_END_IO_ERROR(bio);
   #else
                   if (error)
                           dr->dr_error = -(error);
                   else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
                           dr->dr_error = EIO;
   #endif
           }
   
           /* Drop reference acquired by __vdev_disk_physio */
           vdev_disk_dio_put(dr);
   }
   
   static inline void
   vdev_submit_bio_impl(struct bio *bio)
   {
   #ifdef HAVE_1ARG_SUBMIT_BIO
           (void) submit_bio(bio);
   #else
           (void) submit_bio(bio_data_dir(bio), bio);
   #endif
   }
   
   /*
    * preempt_schedule_notrace is GPL-only which breaks the ZFS build, so
    * replace it with preempt_schedule under the following condition:
    */
   #if defined(CONFIG_ARM64) && \
       defined(CONFIG_PREEMPTION) && \
       defined(CONFIG_BLK_CGROUP)
   #define preempt_schedule_notrace(x) preempt_schedule(x)
   #endif
   
   /*
    * As for the Linux 5.18 kernel bio_alloc() expects a block_device struct
    * as an argument removing the need to set it with bio_set_dev().  This
    * removes the need for all of the following compatibility code.
    */
   #if !defined(HAVE_BIO_ALLOC_4ARG)
   
   #ifdef HAVE_BIO_SET_DEV
   #if defined(CONFIG_BLK_CGROUP) && defined(HAVE_BIO_SET_DEV_GPL_ONLY)
   /*
    * The Linux 5.5 kernel updated percpu_ref_tryget() which is inlined by
    * blkg_tryget() to use rcu_read_lock() instead of rcu_read_lock_sched().
    * As a side effect the function was converted to GPL-only.  Define our
    * own version when needed which uses rcu_read_lock_sched().
    *
    * The Linux 5.17 kernel split linux/blk-cgroup.h into a private and a public
    * part, moving blkg_tryget into the private one. Define our own version.
    */
   #if defined(HAVE_BLKG_TRYGET_GPL_ONLY) || !defined(HAVE_BLKG_TRYGET)
   static inline bool
   vdev_blkg_tryget(struct blkcg_gq *blkg)
   {
           struct percpu_ref *ref = &blkg->refcnt;
           unsigned long __percpu *count;
           bool rc;
   
           rcu_read_lock_sched();
   
           if (__ref_is_percpu(ref, &count)) {
                   this_cpu_inc(*count);
                   rc = true;
           } else {
   #ifdef ZFS_PERCPU_REF_COUNT_IN_DATA
                   rc = atomic_long_inc_not_zero(&ref->data->count);
   #else
                   rc = atomic_long_inc_not_zero(&ref->count);
   #endif
           }
   
           rcu_read_unlock_sched();
   
           return (rc);
   }
   #else
   #define vdev_blkg_tryget(bg)    blkg_tryget(bg)
   #endif
   #ifdef HAVE_BIO_SET_DEV_MACRO
   /*
    * The Linux 5.0 kernel updated the bio_set_dev() macro so it calls the
    * GPL-only bio_associate_blkg() symbol thus inadvertently converting
    * the entire macro.  Provide a minimal version which always assigns the
    * request queue's root_blkg to the bio.
    */
   static inline void
   vdev_bio_associate_blkg(struct bio *bio)
   {
   #if defined(HAVE_BIO_BDEV_DISK)
           struct request_queue *q = bio->bi_bdev->bd_disk->queue;
   #else
           struct request_queue *q = bio->bi_disk->queue;
   #endif
   
           ASSERT3P(q, !=, NULL);
           ASSERT3P(bio->bi_blkg, ==, NULL);
   
           if (q->root_blkg && vdev_blkg_tryget(q->root_blkg))
                   bio->bi_blkg = q->root_blkg;
   }
   
   #define bio_associate_blkg vdev_bio_associate_blkg
   #else
   static inline void
   vdev_bio_set_dev(struct bio *bio, struct block_device *bdev)
   {
   #if defined(HAVE_BIO_BDEV_DISK)
           struct request_queue *q = bdev->bd_disk->queue;
   #else
           struct request_queue *q = bio->bi_disk->queue;
   #endif
           bio_clear_flag(bio, BIO_REMAPPED);
           if (bio->bi_bdev != bdev)
                   bio_clear_flag(bio, BIO_THROTTLED);
           bio->bi_bdev = bdev;
   
           ASSERT3P(q, !=, NULL);
           ASSERT3P(bio->bi_blkg, ==, NULL);
   
           if (q->root_blkg && vdev_blkg_tryget(q->root_blkg))
                   bio->bi_blkg = q->root_blkg;
   }
   #define bio_set_dev             vdev_bio_set_dev
   #endif
   #endif
   #else
   /*
    * Provide a bio_set_dev() helper macro for pre-Linux 4.14 kernels.
    */
   static inline void
   bio_set_dev(struct bio *bio, struct block_device *bdev)
   {
           bio->bi_bdev = bdev;
   }
   #endif /* HAVE_BIO_SET_DEV */
   #endif /* !HAVE_BIO_ALLOC_4ARG */
   
   static inline void
   vdev_submit_bio(struct bio *bio)
   {
           struct bio_list *bio_list = current->bio_list;
           current->bio_list = NULL;
           vdev_submit_bio_impl(bio);
           current->bio_list = bio_list;
   }
   
   static inline struct bio *
   vdev_bio_alloc(struct block_device *bdev, gfp_t gfp_mask,
       unsigned short nr_vecs)
   {
           struct bio *bio;
   
   #ifdef HAVE_BIO_ALLOC_4ARG
           bio = bio_alloc(bdev, nr_vecs, 0, gfp_mask);
   #else
           bio = bio_alloc(gfp_mask, nr_vecs);
           if (likely(bio != NULL))
                   bio_set_dev(bio, bdev);
   #endif
   
           return (bio);
   }
   
   static inline unsigned int
   vdev_bio_max_segs(zio_t *zio, int bio_size, uint64_t abd_offset)
   {
           unsigned long nr_segs = abd_nr_pages_off(zio->io_abd,
               bio_size, abd_offset);
   
   #ifdef HAVE_BIO_MAX_SEGS
           return (bio_max_segs(nr_segs));
   #else
           return (MIN(nr_segs, BIO_MAX_PAGES));
   #endif
   }
   
   static int
   __vdev_disk_physio(struct block_device *bdev, zio_t *zio,
       size_t io_size, uint64_t io_offset, int rw, int flags)
   {
           dio_request_t *dr;
           uint64_t abd_offset;
           uint64_t bio_offset;
           int bio_size;
           int bio_count = 16;
           int error = 0;
           struct blk_plug plug;
           unsigned short nr_vecs;
   
           /*
            * Accessing outside the block device is never allowed.
            */
           if (io_offset + io_size > bdev->bd_inode->i_size) {
                   vdev_dbgmsg(zio->io_vd,
                       "Illegal access %llu size %llu, device size %llu",
                       (u_longlong_t)io_offset,
                       (u_longlong_t)io_size,
                       (u_longlong_t)i_size_read(bdev->bd_inode));
                   return (SET_ERROR(EIO));
           }
   
   retry:
           dr = vdev_disk_dio_alloc(bio_count);
   
           if (!(zio->io_flags & (ZIO_FLAG_IO_RETRY | ZIO_FLAG_TRYHARD)) &&
               zio->io_vd->vdev_failfast == B_TRUE) {
                   bio_set_flags_failfast(bdev, &flags, zfs_vdev_failfast_mask & 1,
                       zfs_vdev_failfast_mask & 2, zfs_vdev_failfast_mask & 4);
           }
   
           dr->dr_zio = zio;
   
           /*
            * Since bio's can have up to BIO_MAX_PAGES=256 iovec's, each of which
            * is at least 512 bytes and at most PAGESIZE (typically 4K), one bio
            * can cover at least 128KB and at most 1MB.  When the required number
            * of iovec's exceeds this, we are forced to break the IO in multiple
            * bio's and wait for them all to complete.  This is likely if the
            * recordsize property is increased beyond 1MB.  The default
            * bio_count=16 should typically accommodate the maximum-size zio of
            * 16MB.
            */
   
           abd_offset = 0;
           bio_offset = io_offset;
           bio_size = io_size;
           for (int i = 0; i <= dr->dr_bio_count; i++) {
   
                   /* Finished constructing bio's for given buffer */
                   if (bio_size <= 0)
                           break;
   
                   /*
                    * If additional bio's are required, we have to retry, but
                    * this should be rare - see the comment above.
                    */
                   if (dr->dr_bio_count == i) {
                           vdev_disk_dio_free(dr);
                           bio_count *= 2;
                           goto retry;
                   }
   
                   nr_vecs = vdev_bio_max_segs(zio, bio_size, abd_offset);
                   dr->dr_bio[i] = vdev_bio_alloc(bdev, GFP_NOIO, nr_vecs);
                   if (unlikely(dr->dr_bio[i] == NULL)) {
                           vdev_disk_dio_free(dr);
                           return (SET_ERROR(ENOMEM));
                   }
   
                   /* Matching put called by vdev_disk_physio_completion */
                   vdev_disk_dio_get(dr);
   
                   BIO_BI_SECTOR(dr->dr_bio[i]) = bio_offset >> 9;
                   dr->dr_bio[i]->bi_end_io = vdev_disk_physio_completion;
                   dr->dr_bio[i]->bi_private = dr;
                   bio_set_op_attrs(dr->dr_bio[i], rw, flags);
   
                   /* Remaining size is returned to become the new size */
                   bio_size = abd_bio_map_off(dr->dr_bio[i], zio->io_abd,
                       bio_size, abd_offset);
   
                   /* Advance in buffer and construct another bio if needed */
                   abd_offset += BIO_BI_SIZE(dr->dr_bio[i]);
                   bio_offset += BIO_BI_SIZE(dr->dr_bio[i]);
           }
   
           /* Extra reference to protect dio_request during vdev_submit_bio */
           vdev_disk_dio_get(dr);
   
           if (dr->dr_bio_count > 1)
                   blk_start_plug(&plug);
   
           /* Submit all bio's associated with this dio */
           for (int i = 0; i < dr->dr_bio_count; i++) {
                   if (dr->dr_bio[i])
                           vdev_submit_bio(dr->dr_bio[i]);
           }
   
           if (dr->dr_bio_count > 1)
                   blk_finish_plug(&plug);
   
           vdev_disk_dio_put(dr);
   
           return (error);
   }
   
   BIO_END_IO_PROTO(vdev_disk_io_flush_completion, bio, error)
   {
           zio_t *zio = bio->bi_private;
   #ifdef HAVE_1ARG_BIO_END_IO_T
           zio->io_error = BIO_END_IO_ERROR(bio);
   #else
           zio->io_error = -error;
   #endif
   
           if (zio->io_error && (zio->io_error == EOPNOTSUPP))
                   zio->io_vd->vdev_nowritecache = B_TRUE;
   
           bio_put(bio);
           ASSERT3S(zio->io_error, >=, 0);
           if (zio->io_error)
                   vdev_disk_error(zio);
           zio_interrupt(zio);
   }
   
   static int
   vdev_disk_io_flush(struct block_device *bdev, zio_t *zio)
   {
           struct request_queue *q;
           struct bio *bio;
   
           q = bdev_get_queue(bdev);
           if (!q)
                   return (SET_ERROR(ENXIO));
   
           bio = vdev_bio_alloc(bdev, GFP_NOIO, 0);
           if (unlikely(bio == NULL))
                   return (SET_ERROR(ENOMEM));
   
           bio->bi_end_io = vdev_disk_io_flush_completion;
           bio->bi_private = zio;
           bio_set_flush(bio);
           vdev_submit_bio(bio);
           invalidate_bdev(bdev);
   
           return (0);
   }
   
   static int
   vdev_disk_io_trim(zio_t *zio)
   {
           vdev_t *v = zio->io_vd;
           vdev_disk_t *vd = v->vdev_tsd;
   
   #if defined(HAVE_BLKDEV_ISSUE_SECURE_ERASE)
           if (zio->io_trim_flags & ZIO_TRIM_SECURE) {
                   return (-blkdev_issue_secure_erase(vd->vd_bdev,
                       zio->io_offset >> 9, zio->io_size >> 9, GFP_NOFS));
           } else {
                   return (-blkdev_issue_discard(vd->vd_bdev,
                       zio->io_offset >> 9, zio->io_size >> 9, GFP_NOFS));
           }
   #elif defined(HAVE_BLKDEV_ISSUE_DISCARD)
           unsigned long trim_flags = 0;
   #if defined(BLKDEV_DISCARD_SECURE)
           if (zio->io_trim_flags & ZIO_TRIM_SECURE)
                   trim_flags |= BLKDEV_DISCARD_SECURE;
   #endif
           return (-blkdev_issue_discard(vd->vd_bdev,
               zio->io_offset >> 9, zio->io_size >> 9, GFP_NOFS, trim_flags));
   #else
   #error "Unsupported kernel"
   #endif
   }
   
   static void
   vdev_disk_io_start(zio_t *zio)
   {
           vdev_t *v = zio->io_vd;
           vdev_disk_t *vd = v->vdev_tsd;
           int rw, error;
   
           /*
            * If the vdev is closed, it's likely in the REMOVED or FAULTED state.
            * Nothing to be done here but return failure.
            */
           if (vd == NULL) {
                   zio->io_error = ENXIO;
                   zio_interrupt(zio);
                   return;
           }
   
           rw_enter(&vd->vd_lock, RW_READER);
   
           /*
            * If the vdev is closed, it's likely due to a failed reopen and is
            * in the UNAVAIL state.  Nothing to be done here but return failure.
            */
           if (vd->vd_bdev == NULL) {
                   rw_exit(&vd->vd_lock);
                   zio->io_error = ENXIO;
                   zio_interrupt(zio);
                   return;
           }
   
           switch (zio->io_type) {
           case ZIO_TYPE_IOCTL:
   
                   if (!vdev_readable(v)) {
                           rw_exit(&vd->vd_lock);
                           zio->io_error = SET_ERROR(ENXIO);
                           zio_interrupt(zio);
                           return;
                   }
   
                   switch (zio->io_cmd) {
                   case DKIOCFLUSHWRITECACHE:
   
                           if (zfs_nocacheflush)
                                   break;
   
                           if (v->vdev_nowritecache) {
                                   zio->io_error = SET_ERROR(ENOTSUP);
                                   break;
                           }
   
                           error = vdev_disk_io_flush(vd->vd_bdev, zio);
                           if (error == 0) {
                                   rw_exit(&vd->vd_lock);
                                   return;
                           }
   
                           zio->io_error = error;
   
                           break;
   
                   default:
                           zio->io_error = SET_ERROR(ENOTSUP);
                   }
   
                   rw_exit(&vd->vd_lock);
                   zio_execute(zio);
                   return;
           case ZIO_TYPE_WRITE:
                   rw = WRITE;
                   break;
   
           case ZIO_TYPE_READ:
                   rw = READ;
                   break;
   
           case ZIO_TYPE_TRIM:
                   zio->io_error = vdev_disk_io_trim(zio);
                   rw_exit(&vd->vd_lock);
                   zio_interrupt(zio);
                   return;
   
           default:
                   rw_exit(&vd->vd_lock);
                   zio->io_error = SET_ERROR(ENOTSUP);
                   zio_interrupt(zio);
                   return;
           }
   
           zio->io_target_timestamp = zio_handle_io_delay(zio);
           error = __vdev_disk_physio(vd->vd_bdev, zio,
               zio->io_size, zio->io_offset, rw, 0);
           rw_exit(&vd->vd_lock);
   
           if (error) {
                   zio->io_error = error;
                   zio_interrupt(zio);
                   return;
           }
   }
   
   static void
   vdev_disk_io_done(zio_t *zio)
   {
           /*
            * If the device returned EIO, we revalidate the media.  If it is
            * determined the media has changed this triggers the asynchronous
            * removal of the device from the configuration.
            */
           if (zio->io_error == EIO) {
                   vdev_t *v = zio->io_vd;
                   vdev_disk_t *vd = v->vdev_tsd;
   
                   if (!zfs_check_disk_status(vd->vd_bdev)) {
                           invalidate_bdev(vd->vd_bdev);
                           v->vdev_remove_wanted = B_TRUE;
                           spa_async_request(zio->io_spa, SPA_ASYNC_REMOVE);
                   }
           }
   }
   
   static void
   vdev_disk_hold(vdev_t *vd)
   {
           ASSERT(spa_config_held(vd->vdev_spa, SCL_STATE, RW_WRITER));
   
           /* We must have a pathname, and it must be absolute. */
           if (vd->vdev_path == NULL || vd->vdev_path[0] != '/')
                   return;
   
           /*
            * Only prefetch path and devid info if the device has
            * never been opened.
            */
           if (vd->vdev_tsd != NULL)
                   return;
   
   }
   
   static void
   vdev_disk_rele(vdev_t *vd)
   {
           ASSERT(spa_config_held(vd->vdev_spa, SCL_STATE, RW_WRITER));
   
           /* XXX: Implement me as a vnode rele for the device */
   }
   
   vdev_ops_t vdev_disk_ops = {
           .vdev_op_init = NULL,
           .vdev_op_fini = NULL,
           .vdev_op_open = vdev_disk_open,
           .vdev_op_close = vdev_disk_close,
           .vdev_op_asize = vdev_default_asize,
           .vdev_op_min_asize = vdev_default_min_asize,
           .vdev_op_min_alloc = NULL,
           .vdev_op_io_start = vdev_disk_io_start,
           .vdev_op_io_done = vdev_disk_io_done,
           .vdev_op_state_change = NULL,
           .vdev_op_need_resilver = NULL,
           .vdev_op_hold = vdev_disk_hold,
           .vdev_op_rele = vdev_disk_rele,
           .vdev_op_remap = NULL,
           .vdev_op_xlate = vdev_default_xlate,
           .vdev_op_rebuild_asize = NULL,
           .vdev_op_metaslab_init = NULL,
           .vdev_op_config_generate = NULL,
           .vdev_op_nparity = NULL,
           .vdev_op_ndisks = NULL,
           .vdev_op_type = VDEV_TYPE_DISK,         /* name of this vdev type */
           .vdev_op_leaf = B_TRUE,                 /* leaf vdev */
           .vdev_op_kobj_evt_post = vdev_disk_kobj_evt_post
   };
   
   /*
    * The zfs_vdev_scheduler module option has been deprecated. Setting this
    * value no longer has any effect.  It has not yet been entirely removed
    * to allow the module to be loaded if this option is specified in the
    * /etc/modprobe.d/zfs.conf file.  The following warning will be logged.
    */
   static int
   param_set_vdev_scheduler(const char *val, zfs_kernel_param_t *kp)
   {
           int error = param_set_charp(val, kp);
           if (error == 0) {
                  printk(KERN_INFO "The 'zfs_vdev_scheduler' module option "
                      "is not supported.\n");
          }
  
          return (error);
  }
  
  static const char *zfs_vdev_scheduler = "unused";
  module_param_call(zfs_vdev_scheduler, param_set_vdev_scheduler,
      param_get_charp, &zfs_vdev_scheduler, 0644);
  MODULE_PARM_DESC(zfs_vdev_scheduler, "I/O scheduler");
  
  int
  param_set_min_auto_ashift(const char *buf, zfs_kernel_param_t *kp)
  {
          uint_t val;
          int error;
  
          error = kstrtouint(buf, 0, &val);
          if (error < 0)
                  return (SET_ERROR(error));
  
          if (val < ASHIFT_MIN || val > zfs_vdev_max_auto_ashift)
                  return (SET_ERROR(-EINVAL));
  
          error = param_set_uint(buf, kp);
          if (error < 0)
                  return (SET_ERROR(error));
  
          return (0);
  }
  
  int
  param_set_max_auto_ashift(const char *buf, zfs_kernel_param_t *kp)
  {
          uint_t val;
          int error;
  
          error = kstrtouint(buf, 0, &val);
          if (error < 0)
                  return (SET_ERROR(error));
  
          if (val > ASHIFT_MAX || val < zfs_vdev_min_auto_ashift)
                  return (SET_ERROR(-EINVAL));
  
          error = param_set_uint(buf, kp);
          if (error < 0)
                  return (SET_ERROR(error));
  
          return (0);
  }
  
  ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, open_timeout_ms, UINT, ZMOD_RW,
          "Timeout before determining that a device is missing");
  
  ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, failfast_mask, UINT, ZMOD_RW,
          "Defines failfast mask: 1 - device, 2 - transport, 4 - driver");

Cache object: 2017e7df75dae3104011d3563069891d