Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm

[linux-2.6-microblaze.git] / fs / xfs / xfs_mount.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_bit.h"
#include "xfs_sb.h"
#include "xfs_mount.h"
#include "xfs_inode.h"
#include "xfs_dir2.h"
#include "xfs_ialloc.h"
#include "xfs_alloc.h"
#include "xfs_rtalloc.h"
#include "xfs_bmap.h"
#include "xfs_trans.h"
#include "xfs_trans_priv.h"
#include "xfs_log.h"
#include "xfs_error.h"
#include "xfs_quota.h"
#include "xfs_fsops.h"
#include "xfs_icache.h"
#include "xfs_sysfs.h"
#include "xfs_rmap_btree.h"
#include "xfs_refcount_btree.h"
#include "xfs_reflink.h"
#include "xfs_extent_busy.h"
#include "xfs_health.h"
#include "xfs_trace.h"
#include "xfs_ag.h"

static DEFINE_MUTEX(xfs_uuid_table_mutex);
static int xfs_uuid_table_size;
static uuid_t *xfs_uuid_table;

void
xfs_uuid_table_free(void)
{
        if (xfs_uuid_table_size == 0)
                return;
        kmem_free(xfs_uuid_table);
        xfs_uuid_table = NULL;
        xfs_uuid_table_size = 0;
}

/*
 * See if the UUID is unique among mounted XFS filesystems.
 * Mount fails if UUID is nil or a FS with the same UUID is already mounted.
 */
STATIC int
xfs_uuid_mount(
        struct xfs_mount        *mp)
{
        uuid_t                  *uuid = &mp->m_sb.sb_uuid;
        int                     hole, i;

        /* Publish UUID in struct super_block */
        uuid_copy(&mp->m_super->s_uuid, uuid);

        if (xfs_has_nouuid(mp))
                return 0;

        if (uuid_is_null(uuid)) {
                xfs_warn(mp, "Filesystem has null UUID - can't mount");
                return -EINVAL;
        }

        mutex_lock(&xfs_uuid_table_mutex);
        for (i = 0, hole = -1; i < xfs_uuid_table_size; i++) {
                if (uuid_is_null(&xfs_uuid_table[i])) {
                        hole = i;
                        continue;
                }
                if (uuid_equal(uuid, &xfs_uuid_table[i]))
                        goto out_duplicate;
        }

        if (hole < 0) {
                xfs_uuid_table = krealloc(xfs_uuid_table,
                        (xfs_uuid_table_size + 1) * sizeof(*xfs_uuid_table),
                        GFP_KERNEL | __GFP_NOFAIL);
                hole = xfs_uuid_table_size++;
        }
        xfs_uuid_table[hole] = *uuid;
        mutex_unlock(&xfs_uuid_table_mutex);

        return 0;

 out_duplicate:
        mutex_unlock(&xfs_uuid_table_mutex);
        xfs_warn(mp, "Filesystem has duplicate UUID %pU - can't mount", uuid);
        return -EINVAL;
}

STATIC void
xfs_uuid_unmount(
        struct xfs_mount        *mp)
{
        uuid_t                  *uuid = &mp->m_sb.sb_uuid;
        int                     i;

        if (xfs_has_nouuid(mp))
                return;

        mutex_lock(&xfs_uuid_table_mutex);
        for (i = 0; i < xfs_uuid_table_size; i++) {
                if (uuid_is_null(&xfs_uuid_table[i]))
                        continue;
                if (!uuid_equal(uuid, &xfs_uuid_table[i]))
                        continue;
                memset(&xfs_uuid_table[i], 0, sizeof(uuid_t));
                break;
        }
        ASSERT(i < xfs_uuid_table_size);
        mutex_unlock(&xfs_uuid_table_mutex);
}

/*
 * Check size of device based on the (data/realtime) block count.
 * Note: this check is used by the growfs code as well as mount.
 */
int
xfs_sb_validate_fsb_count(
        xfs_sb_t        *sbp,
        uint64_t        nblocks)
{
        ASSERT(PAGE_SHIFT >= sbp->sb_blocklog);
        ASSERT(sbp->sb_blocklog >= BBSHIFT);

        /* Limited by ULONG_MAX of page cache index */
        if (nblocks >> (PAGE_SHIFT - sbp->sb_blocklog) > ULONG_MAX)
                return -EFBIG;
        return 0;
}

/*
 * xfs_readsb
 *
 * Does the initial read of the superblock.
 */
int
xfs_readsb(
        struct xfs_mount *mp,
        int             flags)
{
        unsigned int    sector_size;
        struct xfs_buf  *bp;
        struct xfs_sb   *sbp = &mp->m_sb;
        int             error;
        int             loud = !(flags & XFS_MFSI_QUIET);
        const struct xfs_buf_ops *buf_ops;

        ASSERT(mp->m_sb_bp == NULL);
        ASSERT(mp->m_ddev_targp != NULL);

        /*
         * For the initial read, we must guess at the sector
         * size based on the block device.  It's enough to
         * get the sb_sectsize out of the superblock and
         * then reread with the proper length.
         * We don't verify it yet, because it may not be complete.
         */
        sector_size = xfs_getsize_buftarg(mp->m_ddev_targp);
        buf_ops = NULL;

        /*
         * Allocate a (locked) buffer to hold the superblock. This will be kept
         * around at all times to optimize access to the superblock. Therefore,
         * set XBF_NO_IOACCT to make sure it doesn't hold the buftarg count
         * elevated.
         */
reread:
        error = xfs_buf_read_uncached(mp->m_ddev_targp, XFS_SB_DADDR,
                                      BTOBB(sector_size), XBF_NO_IOACCT, &bp,
                                      buf_ops);
        if (error) {
                if (loud)
                        xfs_warn(mp, "SB validate failed with error %d.", error);
                /* bad CRC means corrupted metadata */
                if (error == -EFSBADCRC)
                        error = -EFSCORRUPTED;
                return error;
        }

        /*
         * Initialize the mount structure from the superblock.
         */
        xfs_sb_from_disk(sbp, bp->b_addr);

        /*
         * If we haven't validated the superblock, do so now before we try
         * to check the sector size and reread the superblock appropriately.
         */
        if (sbp->sb_magicnum != XFS_SB_MAGIC) {
                if (loud)
                        xfs_warn(mp, "Invalid superblock magic number");
                error = -EINVAL;
                goto release_buf;
        }

        /*
         * We must be able to do sector-sized and sector-aligned IO.
         */
        if (sector_size > sbp->sb_sectsize) {
                if (loud)
                        xfs_warn(mp, "device supports %u byte sectors (not %u)",
                                sector_size, sbp->sb_sectsize);
                error = -ENOSYS;
                goto release_buf;
        }

        if (buf_ops == NULL) {
                /*
                 * Re-read the superblock so the buffer is correctly sized,
                 * and properly verified.
                 */
                xfs_buf_relse(bp);
                sector_size = sbp->sb_sectsize;
                buf_ops = loud ? &xfs_sb_buf_ops : &xfs_sb_quiet_buf_ops;
                goto reread;
        }

        mp->m_features |= xfs_sb_version_to_features(sbp);
        xfs_reinit_percpu_counters(mp);

        /* no need to be quiet anymore, so reset the buf ops */
        bp->b_ops = &xfs_sb_buf_ops;

        mp->m_sb_bp = bp;
        xfs_buf_unlock(bp);
        return 0;

release_buf:
        xfs_buf_relse(bp);
        return error;
}

/*
 * If the sunit/swidth change would move the precomputed root inode value, we
 * must reject the ondisk change because repair will stumble over that.
 * However, we allow the mount to proceed because we never rejected this
 * combination before.  Returns true to update the sb, false otherwise.
 */
static inline int
xfs_check_new_dalign(
        struct xfs_mount        *mp,
        int                     new_dalign,
        bool                    *update_sb)
{
        struct xfs_sb           *sbp = &mp->m_sb;
        xfs_ino_t               calc_ino;

        calc_ino = xfs_ialloc_calc_rootino(mp, new_dalign);
        trace_xfs_check_new_dalign(mp, new_dalign, calc_ino);

        if (sbp->sb_rootino == calc_ino) {
                *update_sb = true;
                return 0;
        }

        xfs_warn(mp,
"Cannot change stripe alignment; would require moving root inode.");

        /*
         * XXX: Next time we add a new incompat feature, this should start
         * returning -EINVAL to fail the mount.  Until then, spit out a warning
         * that we're ignoring the administrator's instructions.
         */
        xfs_warn(mp, "Skipping superblock stripe alignment update.");
        *update_sb = false;
        return 0;
}

/*
 * If we were provided with new sunit/swidth values as mount options, make sure
 * that they pass basic alignment and superblock feature checks, and convert
 * them into the same units (FSB) that everything else expects.  This step
 * /must/ be done before computing the inode geometry.
 */
STATIC int
xfs_validate_new_dalign(
        struct xfs_mount        *mp)
{
        if (mp->m_dalign == 0)
                return 0;

        /*
         * If stripe unit and stripe width are not multiples
         * of the fs blocksize turn off alignment.
         */
        if ((BBTOB(mp->m_dalign) & mp->m_blockmask) ||
            (BBTOB(mp->m_swidth) & mp->m_blockmask)) {
                xfs_warn(mp,
        "alignment check failed: sunit/swidth vs. blocksize(%d)",
                        mp->m_sb.sb_blocksize);
                return -EINVAL;
        } else {
                /*
                 * Convert the stripe unit and width to FSBs.
                 */
                mp->m_dalign = XFS_BB_TO_FSBT(mp, mp->m_dalign);
                if (mp->m_dalign && (mp->m_sb.sb_agblocks % mp->m_dalign)) {
                        xfs_warn(mp,
                "alignment check failed: sunit/swidth vs. agsize(%d)",
                                 mp->m_sb.sb_agblocks);
                        return -EINVAL;
                } else if (mp->m_dalign) {
                        mp->m_swidth = XFS_BB_TO_FSBT(mp, mp->m_swidth);
                } else {
                        xfs_warn(mp,
                "alignment check failed: sunit(%d) less than bsize(%d)",
                                 mp->m_dalign, mp->m_sb.sb_blocksize);
                        return -EINVAL;
                }
        }

        if (!xfs_has_dalign(mp)) {
                xfs_warn(mp,
"cannot change alignment: superblock does not support data alignment");
                return -EINVAL;
        }

        return 0;
}

/* Update alignment values based on mount options and sb values. */
STATIC int
xfs_update_alignment(
        struct xfs_mount        *mp)
{
        struct xfs_sb           *sbp = &mp->m_sb;

        if (mp->m_dalign) {
                bool            update_sb;
                int             error;

                if (sbp->sb_unit == mp->m_dalign &&
                    sbp->sb_width == mp->m_swidth)
                        return 0;

                error = xfs_check_new_dalign(mp, mp->m_dalign, &update_sb);
                if (error || !update_sb)
                        return error;

                sbp->sb_unit = mp->m_dalign;
                sbp->sb_width = mp->m_swidth;
                mp->m_update_sb = true;
        } else if (!xfs_has_noalign(mp) && xfs_has_dalign(mp)) {
                mp->m_dalign = sbp->sb_unit;
                mp->m_swidth = sbp->sb_width;
        }

        return 0;
}

/*
 * precalculate the low space thresholds for dynamic speculative preallocation.
 */
void
xfs_set_low_space_thresholds(
        struct xfs_mount        *mp)
{
        uint64_t                dblocks = mp->m_sb.sb_dblocks;
        uint64_t                rtexts = mp->m_sb.sb_rextents;
        int                     i;

        do_div(dblocks, 100);
        do_div(rtexts, 100);

        for (i = 0; i < XFS_LOWSP_MAX; i++) {
                mp->m_low_space[i] = dblocks * (i + 1);
                mp->m_low_rtexts[i] = rtexts * (i + 1);
        }
}

/*
 * Check that the data (and log if separate) is an ok size.
 */
STATIC int
xfs_check_sizes(
        struct xfs_mount *mp)
{
        struct xfs_buf  *bp;
        xfs_daddr_t     d;
        int             error;

        d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks);
        if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_dblocks) {
                xfs_warn(mp, "filesystem size mismatch detected");
                return -EFBIG;
        }
        error = xfs_buf_read_uncached(mp->m_ddev_targp,
                                        d - XFS_FSS_TO_BB(mp, 1),
                                        XFS_FSS_TO_BB(mp, 1), 0, &bp, NULL);
        if (error) {
                xfs_warn(mp, "last sector read failed");
                return error;
        }
        xfs_buf_relse(bp);

        if (mp->m_logdev_targp == mp->m_ddev_targp)
                return 0;

        d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_logblocks);
        if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_logblocks) {
                xfs_warn(mp, "log size mismatch detected");
                return -EFBIG;
        }
        error = xfs_buf_read_uncached(mp->m_logdev_targp,
                                        d - XFS_FSB_TO_BB(mp, 1),
                                        XFS_FSB_TO_BB(mp, 1), 0, &bp, NULL);
        if (error) {
                xfs_warn(mp, "log device read failed");
                return error;
        }
        xfs_buf_relse(bp);
        return 0;
}

/*
 * Clear the quotaflags in memory and in the superblock.
 */
int
xfs_mount_reset_sbqflags(
        struct xfs_mount        *mp)
{
        mp->m_qflags = 0;

        /* It is OK to look at sb_qflags in the mount path without m_sb_lock. */
        if (mp->m_sb.sb_qflags == 0)
                return 0;
        spin_lock(&mp->m_sb_lock);
        mp->m_sb.sb_qflags = 0;
        spin_unlock(&mp->m_sb_lock);

        if (!xfs_fs_writable(mp, SB_FREEZE_WRITE))
                return 0;

        return xfs_sync_sb(mp, false);
}

uint64_t
xfs_default_resblks(xfs_mount_t *mp)
{
        uint64_t resblks;

        /*
         * We default to 5% or 8192 fsbs of space reserved, whichever is
         * smaller.  This is intended to cover concurrent allocation
         * transactions when we initially hit enospc. These each require a 4
         * block reservation. Hence by default we cover roughly 2000 concurrent
         * allocation reservations.
         */
        resblks = mp->m_sb.sb_dblocks;
        do_div(resblks, 20);
        resblks = min_t(uint64_t, resblks, 8192);
        return resblks;
}

/* Ensure the summary counts are correct. */
STATIC int
xfs_check_summary_counts(
        struct xfs_mount        *mp)
{
        /*
         * The AG0 superblock verifier rejects in-progress filesystems,
         * so we should never see the flag set this far into mounting.
         */
        if (mp->m_sb.sb_inprogress) {
                xfs_err(mp, "sb_inprogress set after log recovery??");
                WARN_ON(1);
                return -EFSCORRUPTED;
        }

        /*
         * Now the log is mounted, we know if it was an unclean shutdown or
         * not. If it was, with the first phase of recovery has completed, we
         * have consistent AG blocks on disk. We have not recovered EFIs yet,
         * but they are recovered transactionally in the second recovery phase
         * later.
         *
         * If the log was clean when we mounted, we can check the summary
         * counters.  If any of them are obviously incorrect, we can recompute
         * them from the AGF headers in the next step.
         */
        if (xfs_is_clean(mp) &&
            (mp->m_sb.sb_fdblocks > mp->m_sb.sb_dblocks ||
             !xfs_verify_icount(mp, mp->m_sb.sb_icount) ||
             mp->m_sb.sb_ifree > mp->m_sb.sb_icount))
                xfs_fs_mark_sick(mp, XFS_SICK_FS_COUNTERS);

        /*
         * We can safely re-initialise incore superblock counters from the
         * per-ag data. These may not be correct if the filesystem was not
         * cleanly unmounted, so we waited for recovery to finish before doing
         * this.
         *
         * If the filesystem was cleanly unmounted or the previous check did
         * not flag anything weird, then we can trust the values in the
         * superblock to be correct and we don't need to do anything here.
         * Otherwise, recalculate the summary counters.
         */
        if ((!xfs_has_lazysbcount(mp) || xfs_is_clean(mp)) &&
            !xfs_fs_has_sickness(mp, XFS_SICK_FS_COUNTERS))
                return 0;

        return xfs_initialize_perag_data(mp, mp->m_sb.sb_agcount);
}

/*
 * Flush and reclaim dirty inodes in preparation for unmount. Inodes and
 * internal inode structures can be sitting in the CIL and AIL at this point,
 * so we need to unpin them, write them back and/or reclaim them before unmount
 * can proceed.  In other words, callers are required to have inactivated all
 * inodes.
 *
 * An inode cluster that has been freed can have its buffer still pinned in
 * memory because the transaction is still sitting in a iclog. The stale inodes
 * on that buffer will be pinned to the buffer until the transaction hits the
 * disk and the callbacks run. Pushing the AIL will skip the stale inodes and
 * may never see the pinned buffer, so nothing will push out the iclog and
 * unpin the buffer.
 *
 * Hence we need to force the log to unpin everything first. However, log
 * forces don't wait for the discards they issue to complete, so we have to
 * explicitly wait for them to complete here as well.
 *
 * Then we can tell the world we are unmounting so that error handling knows
 * that the filesystem is going away and we should error out anything that we
 * have been retrying in the background.  This will prevent never-ending
 * retries in AIL pushing from hanging the unmount.
 *
 * Finally, we can push the AIL to clean all the remaining dirty objects, then
 * reclaim the remaining inodes that are still in memory at this point in time.
 */
static void
xfs_unmount_flush_inodes(
        struct xfs_mount        *mp)
{
        xfs_log_force(mp, XFS_LOG_SYNC);
        xfs_extent_busy_wait_all(mp);
        flush_workqueue(xfs_discard_wq);

        set_bit(XFS_OPSTATE_UNMOUNTING, &mp->m_opstate);

        xfs_ail_push_all_sync(mp->m_ail);
        xfs_inodegc_stop(mp);
        cancel_delayed_work_sync(&mp->m_reclaim_work);
        xfs_reclaim_inodes(mp);
        xfs_health_unmount(mp);
}

static void
xfs_mount_setup_inode_geom(
        struct xfs_mount        *mp)
{
        struct xfs_ino_geometry *igeo = M_IGEO(mp);

        igeo->attr_fork_offset = xfs_bmap_compute_attr_offset(mp);
        ASSERT(igeo->attr_fork_offset < XFS_LITINO(mp));

        xfs_ialloc_setup_geometry(mp);
}

/* Compute maximum possible height for per-AG btree types for this fs. */
static inline void
xfs_agbtree_compute_maxlevels(
        struct xfs_mount        *mp)
{
        unsigned int            levels;

        levels = max(mp->m_alloc_maxlevels, M_IGEO(mp)->inobt_maxlevels);
        levels = max(levels, mp->m_rmap_maxlevels);
        mp->m_agbtree_maxlevels = max(levels, mp->m_refc_maxlevels);
}

/*
 * This function does the following on an initial mount of a file system:
 *      - reads the superblock from disk and init the mount struct
 *      - if we're a 32-bit kernel, do a size check on the superblock
 *              so we don't mount terabyte filesystems
 *      - init mount struct realtime fields
 *      - allocate inode hash table for fs
 *      - init directory manager
 *      - perform recovery and init the log manager
 */
int
xfs_mountfs(
        struct xfs_mount        *mp)
{
        struct xfs_sb           *sbp = &(mp->m_sb);
        struct xfs_inode        *rip;
        struct xfs_ino_geometry *igeo = M_IGEO(mp);
        uint64_t                resblks;
        uint                    quotamount = 0;
        uint                    quotaflags = 0;
        int                     error = 0;

        xfs_sb_mount_common(mp, sbp);

        /*
         * Check for a mismatched features2 values.  Older kernels read & wrote
         * into the wrong sb offset for sb_features2 on some platforms due to
         * xfs_sb_t not being 64bit size aligned when sb_features2 was added,
         * which made older superblock reading/writing routines swap it as a
         * 64-bit value.
         *
         * For backwards compatibility, we make both slots equal.
         *
         * If we detect a mismatched field, we OR the set bits into the existing
         * features2 field in case it has already been modified; we don't want
         * to lose any features.  We then update the bad location with the ORed
         * value so that older kernels will see any features2 flags. The
         * superblock writeback code ensures the new sb_features2 is copied to
         * sb_bad_features2 before it is logged or written to disk.
         */
        if (xfs_sb_has_mismatched_features2(sbp)) {
                xfs_warn(mp, "correcting sb_features alignment problem");
                sbp->sb_features2 |= sbp->sb_bad_features2;
                mp->m_update_sb = true;
        }


        /* always use v2 inodes by default now */
        if (!(mp->m_sb.sb_versionnum & XFS_SB_VERSION_NLINKBIT)) {
                mp->m_sb.sb_versionnum |= XFS_SB_VERSION_NLINKBIT;
                mp->m_features |= XFS_FEAT_NLINK;
                mp->m_update_sb = true;
        }

        /*
         * If we were given new sunit/swidth options, do some basic validation
         * checks and convert the incore dalign and swidth values to the
         * same units (FSB) that everything else uses.  This /must/ happen
         * before computing the inode geometry.
         */
        error = xfs_validate_new_dalign(mp);
        if (error)
                goto out;

        xfs_alloc_compute_maxlevels(mp);
        xfs_bmap_compute_maxlevels(mp, XFS_DATA_FORK);
        xfs_bmap_compute_maxlevels(mp, XFS_ATTR_FORK);
        xfs_mount_setup_inode_geom(mp);
        xfs_rmapbt_compute_maxlevels(mp);
        xfs_refcountbt_compute_maxlevels(mp);

        xfs_agbtree_compute_maxlevels(mp);

        /*
         * Check if sb_agblocks is aligned at stripe boundary.  If sb_agblocks
         * is NOT aligned turn off m_dalign since allocator alignment is within
         * an ag, therefore ag has to be aligned at stripe boundary.  Note that
         * we must compute the free space and rmap btree geometry before doing
         * this.
         */
        error = xfs_update_alignment(mp);
        if (error)
                goto out;

        /* enable fail_at_unmount as default */
        mp->m_fail_unmount = true;

        error = xfs_sysfs_init(&mp->m_kobj, &xfs_mp_ktype,
                               NULL, mp->m_super->s_id);
        if (error)
                goto out;

        error = xfs_sysfs_init(&mp->m_stats.xs_kobj, &xfs_stats_ktype,
                               &mp->m_kobj, "stats");
        if (error)
                goto out_remove_sysfs;

        error = xfs_error_sysfs_init(mp);
        if (error)
                goto out_del_stats;

        error = xfs_errortag_init(mp);
        if (error)
                goto out_remove_error_sysfs;

        error = xfs_uuid_mount(mp);
        if (error)
                goto out_remove_errortag;

        /*
         * Update the preferred write size based on the information from the
         * on-disk superblock.
         */
        mp->m_allocsize_log =
                max_t(uint32_t, sbp->sb_blocklog, mp->m_allocsize_log);
        mp->m_allocsize_blocks = 1U << (mp->m_allocsize_log - sbp->sb_blocklog);

        /* set the low space thresholds for dynamic preallocation */
        xfs_set_low_space_thresholds(mp);

        /*
         * If enabled, sparse inode chunk alignment is expected to match the
         * cluster size. Full inode chunk alignment must match the chunk size,
         * but that is checked on sb read verification...
         */
        if (xfs_has_sparseinodes(mp) &&
            mp->m_sb.sb_spino_align !=
                        XFS_B_TO_FSBT(mp, igeo->inode_cluster_size_raw)) {
                xfs_warn(mp,
        "Sparse inode block alignment (%u) must match cluster size (%llu).",
                         mp->m_sb.sb_spino_align,
                         XFS_B_TO_FSBT(mp, igeo->inode_cluster_size_raw));
                error = -EINVAL;
                goto out_remove_uuid;
        }

        /*
         * Check that the data (and log if separate) is an ok size.
         */
        error = xfs_check_sizes(mp);
        if (error)
                goto out_remove_uuid;

        /*
         * Initialize realtime fields in the mount structure
         */
        error = xfs_rtmount_init(mp);
        if (error) {
                xfs_warn(mp, "RT mount failed");
                goto out_remove_uuid;
        }

        /*
         *  Copies the low order bits of the timestamp and the randomly
         *  set "sequence" number out of a UUID.
         */
        mp->m_fixedfsid[0] =
                (get_unaligned_be16(&sbp->sb_uuid.b[8]) << 16) |
                 get_unaligned_be16(&sbp->sb_uuid.b[4]);
        mp->m_fixedfsid[1] = get_unaligned_be32(&sbp->sb_uuid.b[0]);

        error = xfs_da_mount(mp);
        if (error) {
                xfs_warn(mp, "Failed dir/attr init: %d", error);
                goto out_remove_uuid;
        }

        /*
         * Initialize the precomputed transaction reservations values.
         */
        xfs_trans_init(mp);

        /*
         * Allocate and initialize the per-ag data.
         */
        error = xfs_initialize_perag(mp, sbp->sb_agcount, &mp->m_maxagi);
        if (error) {
                xfs_warn(mp, "Failed per-ag init: %d", error);
                goto out_free_dir;
        }

        if (XFS_IS_CORRUPT(mp, !sbp->sb_logblocks)) {
                xfs_warn(mp, "no log defined");
                error = -EFSCORRUPTED;
                goto out_free_perag;
        }

        error = xfs_inodegc_register_shrinker(mp);
        if (error)
                goto out_fail_wait;

        /*
         * Log's mount-time initialization. The first part of recovery can place
         * some items on the AIL, to be handled when recovery is finished or
         * cancelled.
         */
        error = xfs_log_mount(mp, mp->m_logdev_targp,
                              XFS_FSB_TO_DADDR(mp, sbp->sb_logstart),
                              XFS_FSB_TO_BB(mp, sbp->sb_logblocks));
        if (error) {
                xfs_warn(mp, "log mount failed");
                goto out_inodegc_shrinker;
        }

        /* Make sure the summary counts are ok. */
        error = xfs_check_summary_counts(mp);
        if (error)
                goto out_log_dealloc;

        /* Enable background inode inactivation workers. */
        xfs_inodegc_start(mp);
        xfs_blockgc_start(mp);

        /*
         * Now that we've recovered any pending superblock feature bit
         * additions, we can finish setting up the attr2 behaviour for the
         * mount. The noattr2 option overrides the superblock flag, so only
         * check the superblock feature flag if the mount option is not set.
         */
        if (xfs_has_noattr2(mp)) {
                mp->m_features &= ~XFS_FEAT_ATTR2;
        } else if (!xfs_has_attr2(mp) &&
                   (mp->m_sb.sb_features2 & XFS_SB_VERSION2_ATTR2BIT)) {
                mp->m_features |= XFS_FEAT_ATTR2;
        }

        /*
         * Get and sanity-check the root inode.
         * Save the pointer to it in the mount structure.
         */
        error = xfs_iget(mp, NULL, sbp->sb_rootino, XFS_IGET_UNTRUSTED,
                         XFS_ILOCK_EXCL, &rip);
        if (error) {
                xfs_warn(mp,
                        "Failed to read root inode 0x%llx, error %d",
                        sbp->sb_rootino, -error);
                goto out_log_dealloc;
        }

        ASSERT(rip != NULL);

        if (XFS_IS_CORRUPT(mp, !S_ISDIR(VFS_I(rip)->i_mode))) {
                xfs_warn(mp, "corrupted root inode %llu: not a directory",
                        (unsigned long long)rip->i_ino);
                xfs_iunlock(rip, XFS_ILOCK_EXCL);
                error = -EFSCORRUPTED;
                goto out_rele_rip;
        }
        mp->m_rootip = rip;     /* save it */

        xfs_iunlock(rip, XFS_ILOCK_EXCL);

        /*
         * Initialize realtime inode pointers in the mount structure
         */
        error = xfs_rtmount_inodes(mp);
        if (error) {
                /*
                 * Free up the root inode.
                 */
                xfs_warn(mp, "failed to read RT inodes");
                goto out_rele_rip;
        }

        /*
         * If this is a read-only mount defer the superblock updates until
         * the next remount into writeable mode.  Otherwise we would never
         * perform the update e.g. for the root filesystem.
         */
        if (mp->m_update_sb && !xfs_is_readonly(mp)) {
                error = xfs_sync_sb(mp, false);
                if (error) {
                        xfs_warn(mp, "failed to write sb changes");
                        goto out_rtunmount;
                }
        }

        /*
         * Initialise the XFS quota management subsystem for this mount
         */
        if (XFS_IS_QUOTA_ON(mp)) {
                error = xfs_qm_newmount(mp, &quotamount, &quotaflags);
                if (error)
                        goto out_rtunmount;
        } else {
                /*
                 * If a file system had quotas running earlier, but decided to
                 * mount without -o uquota/pquota/gquota options, revoke the
                 * quotachecked license.
                 */
                if (mp->m_sb.sb_qflags & XFS_ALL_QUOTA_ACCT) {
                        xfs_notice(mp, "resetting quota flags");
                        error = xfs_mount_reset_sbqflags(mp);
                        if (error)
                                goto out_rtunmount;
                }
        }

        /*
         * Finish recovering the file system.  This part needed to be delayed
         * until after the root and real-time bitmap inodes were consistently
         * read in.  Temporarily create per-AG space reservations for metadata
         * btree shape changes because space freeing transactions (for inode
         * inactivation) require the per-AG reservation in lieu of reserving
         * blocks.
         */
        error = xfs_fs_reserve_ag_blocks(mp);
        if (error && error == -ENOSPC)
                xfs_warn(mp,
        "ENOSPC reserving per-AG metadata pool, log recovery may fail.");
        error = xfs_log_mount_finish(mp);
        xfs_fs_unreserve_ag_blocks(mp);
        if (error) {
                xfs_warn(mp, "log mount finish failed");
                goto out_rtunmount;
        }

        /*
         * Now the log is fully replayed, we can transition to full read-only
         * mode for read-only mounts. This will sync all the metadata and clean
         * the log so that the recovery we just performed does not have to be
         * replayed again on the next mount.
         *
         * We use the same quiesce mechanism as the rw->ro remount, as they are
         * semantically identical operations.
         */
        if (xfs_is_readonly(mp) && !xfs_has_norecovery(mp))
                xfs_log_clean(mp);

        /*
         * Complete the quota initialisation, post-log-replay component.
         */
        if (quotamount) {
                ASSERT(mp->m_qflags == 0);
                mp->m_qflags = quotaflags;

                xfs_qm_mount_quotas(mp);
        }

        /*
         * Now we are mounted, reserve a small amount of unused space for
         * privileged transactions. This is needed so that transaction
         * space required for critical operations can dip into this pool
         * when at ENOSPC. This is needed for operations like create with
         * attr, unwritten extent conversion at ENOSPC, etc. Data allocations
         * are not allowed to use this reserved space.
         *
         * This may drive us straight to ENOSPC on mount, but that implies
         * we were already there on the last unmount. Warn if this occurs.
         */
        if (!xfs_is_readonly(mp)) {
                resblks = xfs_default_resblks(mp);
                error = xfs_reserve_blocks(mp, &resblks, NULL);
                if (error)
                        xfs_warn(mp,
        "Unable to allocate reserve blocks. Continuing without reserve pool.");

                /* Reserve AG blocks for future btree expansion. */
                error = xfs_fs_reserve_ag_blocks(mp);
                if (error && error != -ENOSPC)
                        goto out_agresv;
        }

        return 0;

 out_agresv:
        xfs_fs_unreserve_ag_blocks(mp);
        xfs_qm_unmount_quotas(mp);
 out_rtunmount:
        xfs_rtunmount_inodes(mp);
 out_rele_rip:
        xfs_irele(rip);
        /* Clean out dquots that might be in memory after quotacheck. */
        xfs_qm_unmount(mp);

        /*
         * Inactivate all inodes that might still be in memory after a log
         * intent recovery failure so that reclaim can free them.  Metadata
         * inodes and the root directory shouldn't need inactivation, but the
         * mount failed for some reason, so pull down all the state and flee.
         */
        xfs_inodegc_flush(mp);

        /*
         * Flush all inode reclamation work and flush the log.
         * We have to do this /after/ rtunmount and qm_unmount because those
         * two will have scheduled delayed reclaim for the rt/quota inodes.
         *
         * This is slightly different from the unmountfs call sequence
         * because we could be tearing down a partially set up mount.  In
         * particular, if log_mount_finish fails we bail out without calling
         * qm_unmount_quotas and therefore rely on qm_unmount to release the
         * quota inodes.
         */
        xfs_unmount_flush_inodes(mp);
 out_log_dealloc:
        xfs_log_mount_cancel(mp);
 out_inodegc_shrinker:
        unregister_shrinker(&mp->m_inodegc_shrinker);
 out_fail_wait:
        if (mp->m_logdev_targp && mp->m_logdev_targp != mp->m_ddev_targp)
                xfs_buftarg_drain(mp->m_logdev_targp);
        xfs_buftarg_drain(mp->m_ddev_targp);
 out_free_perag:
        xfs_free_perag(mp);
 out_free_dir:
        xfs_da_unmount(mp);
 out_remove_uuid:
        xfs_uuid_unmount(mp);
 out_remove_errortag:
        xfs_errortag_del(mp);
 out_remove_error_sysfs:
        xfs_error_sysfs_del(mp);
 out_del_stats:
        xfs_sysfs_del(&mp->m_stats.xs_kobj);
 out_remove_sysfs:
        xfs_sysfs_del(&mp->m_kobj);
 out:
        return error;
}

/*
 * This flushes out the inodes,dquots and the superblock, unmounts the
 * log and makes sure that incore structures are freed.
 */
void
xfs_unmountfs(
        struct xfs_mount        *mp)
{
        uint64_t                resblks;
        int                     error;

        /*
         * Perform all on-disk metadata updates required to inactivate inodes
         * that the VFS evicted earlier in the unmount process.  Freeing inodes
         * and discarding CoW fork preallocations can cause shape changes to
         * the free inode and refcount btrees, respectively, so we must finish
         * this before we discard the metadata space reservations.  Metadata
         * inodes and the root directory do not require inactivation.
         */
        xfs_inodegc_flush(mp);

        xfs_blockgc_stop(mp);
        xfs_fs_unreserve_ag_blocks(mp);
        xfs_qm_unmount_quotas(mp);
        xfs_rtunmount_inodes(mp);
        xfs_irele(mp->m_rootip);

        xfs_unmount_flush_inodes(mp);

        xfs_qm_unmount(mp);

        /*
         * Unreserve any blocks we have so that when we unmount we don't account
         * the reserved free space as used. This is really only necessary for
         * lazy superblock counting because it trusts the incore superblock
         * counters to be absolutely correct on clean unmount.
         *
         * We don't bother correcting this elsewhere for lazy superblock
         * counting because on mount of an unclean filesystem we reconstruct the
         * correct counter value and this is irrelevant.
         *
         * For non-lazy counter filesystems, this doesn't matter at all because
         * we only every apply deltas to the superblock and hence the incore
         * value does not matter....
         */
        resblks = 0;
        error = xfs_reserve_blocks(mp, &resblks, NULL);
        if (error)
                xfs_warn(mp, "Unable to free reserved block pool. "
                                "Freespace may not be correct on next mount.");

        xfs_log_unmount(mp);
        xfs_da_unmount(mp);
        xfs_uuid_unmount(mp);

#if defined(DEBUG)
        xfs_errortag_clearall(mp);
#endif
        unregister_shrinker(&mp->m_inodegc_shrinker);
        xfs_free_perag(mp);

        xfs_errortag_del(mp);
        xfs_error_sysfs_del(mp);
        xfs_sysfs_del(&mp->m_stats.xs_kobj);
        xfs_sysfs_del(&mp->m_kobj);
}

/*
 * Determine whether modifications can proceed. The caller specifies the minimum
 * freeze level for which modifications should not be allowed. This allows
 * certain operations to proceed while the freeze sequence is in progress, if
 * necessary.
 */
bool
xfs_fs_writable(
        struct xfs_mount        *mp,
        int                     level)
{
        ASSERT(level > SB_UNFROZEN);
        if ((mp->m_super->s_writers.frozen >= level) ||
            xfs_is_shutdown(mp) || xfs_is_readonly(mp))
                return false;

        return true;
}

int
xfs_mod_fdblocks(
        struct xfs_mount        *mp,
        int64_t                 delta,
        bool                    rsvd)
{
        int64_t                 lcounter;
        long long               res_used;
        s32                     batch;
        uint64_t                set_aside;

        if (delta > 0) {
                /*
                 * If the reserve pool is depleted, put blocks back into it
                 * first. Most of the time the pool is full.
                 */
                if (likely(mp->m_resblks == mp->m_resblks_avail)) {
                        percpu_counter_add(&mp->m_fdblocks, delta);
                        return 0;
                }

                spin_lock(&mp->m_sb_lock);
                res_used = (long long)(mp->m_resblks - mp->m_resblks_avail);

                if (res_used > delta) {
                        mp->m_resblks_avail += delta;
                } else {
                        delta -= res_used;
                        mp->m_resblks_avail = mp->m_resblks;
                        percpu_counter_add(&mp->m_fdblocks, delta);
                }
                spin_unlock(&mp->m_sb_lock);
                return 0;
        }

        /*
         * Taking blocks away, need to be more accurate the closer we
         * are to zero.
         *
         * If the counter has a value of less than 2 * max batch size,
         * then make everything serialise as we are real close to
         * ENOSPC.
         */
        if (__percpu_counter_compare(&mp->m_fdblocks, 2 * XFS_FDBLOCKS_BATCH,
                                     XFS_FDBLOCKS_BATCH) < 0)
                batch = 1;
        else
                batch = XFS_FDBLOCKS_BATCH;

        /*
         * Set aside allocbt blocks because these blocks are tracked as free
         * space but not available for allocation. Technically this means that a
         * single reservation cannot consume all remaining free space, but the
         * ratio of allocbt blocks to usable free blocks should be rather small.
         * The tradeoff without this is that filesystems that maintain high
         * perag block reservations can over reserve physical block availability
         * and fail physical allocation, which leads to much more serious
         * problems (i.e. transaction abort, pagecache discards, etc.) than
         * slightly premature -ENOSPC.
         */
        set_aside = mp->m_alloc_set_aside + atomic64_read(&mp->m_allocbt_blks);
        percpu_counter_add_batch(&mp->m_fdblocks, delta, batch);
        if (__percpu_counter_compare(&mp->m_fdblocks, set_aside,
                                     XFS_FDBLOCKS_BATCH) >= 0) {
                /* we had space! */
                return 0;
        }

        /*
         * lock up the sb for dipping into reserves before releasing the space
         * that took us to ENOSPC.
         */
        spin_lock(&mp->m_sb_lock);
        percpu_counter_add(&mp->m_fdblocks, -delta);
        if (!rsvd)
                goto fdblocks_enospc;

        lcounter = (long long)mp->m_resblks_avail + delta;
        if (lcounter >= 0) {
                mp->m_resblks_avail = lcounter;
                spin_unlock(&mp->m_sb_lock);
                return 0;
        }
        xfs_warn_once(mp,
"Reserve blocks depleted! Consider increasing reserve pool size.");

fdblocks_enospc:
        spin_unlock(&mp->m_sb_lock);
        return -ENOSPC;
}

int
xfs_mod_frextents(
        struct xfs_mount        *mp,
        int64_t                 delta)
{
        int64_t                 lcounter;
        int                     ret = 0;

        spin_lock(&mp->m_sb_lock);
        lcounter = mp->m_sb.sb_frextents + delta;
        if (lcounter < 0)
                ret = -ENOSPC;
        else
                mp->m_sb.sb_frextents = lcounter;
        spin_unlock(&mp->m_sb_lock);
        return ret;
}

/*
 * Used to free the superblock along various error paths.
 */
void
xfs_freesb(
        struct xfs_mount        *mp)
{
        struct xfs_buf          *bp = mp->m_sb_bp;

        xfs_buf_lock(bp);
        mp->m_sb_bp = NULL;
        xfs_buf_relse(bp);
}

/*
 * If the underlying (data/log/rt) device is readonly, there are some
 * operations that cannot proceed.
 */
int
xfs_dev_is_read_only(
        struct xfs_mount        *mp,
        char                    *message)
{
        if (xfs_readonly_buftarg(mp->m_ddev_targp) ||
            xfs_readonly_buftarg(mp->m_logdev_targp) ||
            (mp->m_rtdev_targp && xfs_readonly_buftarg(mp->m_rtdev_targp))) {
                xfs_notice(mp, "%s required on read-only device.", message);
                xfs_notice(mp, "write access unavailable, cannot proceed.");
                return -EROFS;
        }
        return 0;
}

/* Force the summary counters to be recalculated at next mount. */
void
xfs_force_summary_recalc(
        struct xfs_mount        *mp)
{
        if (!xfs_has_lazysbcount(mp))
                return;

        xfs_fs_mark_sick(mp, XFS_SICK_FS_COUNTERS);
}

/*
 * Enable a log incompat feature flag in the primary superblock.  The caller
 * cannot have any other transactions in progress.
 */
int
xfs_add_incompat_log_feature(
        struct xfs_mount        *mp,
        uint32_t                feature)
{
        struct xfs_dsb          *dsb;
        int                     error;

        ASSERT(hweight32(feature) == 1);
        ASSERT(!(feature & XFS_SB_FEAT_INCOMPAT_LOG_UNKNOWN));

        /*
         * Force the log to disk and kick the background AIL thread to reduce
         * the chances that the bwrite will stall waiting for the AIL to unpin
         * the primary superblock buffer.  This isn't a data integrity
         * operation, so we don't need a synchronous push.
         */
        error = xfs_log_force(mp, XFS_LOG_SYNC);
        if (error)
                return error;
        xfs_ail_push_all(mp->m_ail);

        /*
         * Lock the primary superblock buffer to serialize all callers that
         * are trying to set feature bits.
         */
        xfs_buf_lock(mp->m_sb_bp);
        xfs_buf_hold(mp->m_sb_bp);

        if (xfs_is_shutdown(mp)) {
                error = -EIO;
                goto rele;
        }

        if (xfs_sb_has_incompat_log_feature(&mp->m_sb, feature))
                goto rele;

        /*
         * Write the primary superblock to disk immediately, because we need
         * the log_incompat bit to be set in the primary super now to protect
         * the log items that we're going to commit later.
         */
        dsb = mp->m_sb_bp->b_addr;
        xfs_sb_to_disk(dsb, &mp->m_sb);
        dsb->sb_features_log_incompat |= cpu_to_be32(feature);
        error = xfs_bwrite(mp->m_sb_bp);
        if (error)
                goto shutdown;

        /*
         * Add the feature bits to the incore superblock before we unlock the
         * buffer.
         */
        xfs_sb_add_incompat_log_features(&mp->m_sb, feature);
        xfs_buf_relse(mp->m_sb_bp);

        /* Log the superblock to disk. */
        return xfs_sync_sb(mp, false);
shutdown:
        xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
rele:
        xfs_buf_relse(mp->m_sb_bp);
        return error;
}

/*
 * Clear all the log incompat flags from the superblock.
 *
 * The caller cannot be in a transaction, must ensure that the log does not
 * contain any log items protected by any log incompat bit, and must ensure
 * that there are no other threads that depend on the state of the log incompat
 * feature flags in the primary super.
 *
 * Returns true if the superblock is dirty.
 */
bool
xfs_clear_incompat_log_features(
        struct xfs_mount        *mp)
{
        bool                    ret = false;

        if (!xfs_has_crc(mp) ||
            !xfs_sb_has_incompat_log_feature(&mp->m_sb,
                                XFS_SB_FEAT_INCOMPAT_LOG_ALL) ||
            xfs_is_shutdown(mp))
                return false;

        /*
         * Update the incore superblock.  We synchronize on the primary super
         * buffer lock to be consistent with the add function, though at least
         * in theory this shouldn't be necessary.
         */
        xfs_buf_lock(mp->m_sb_bp);
        xfs_buf_hold(mp->m_sb_bp);

        if (xfs_sb_has_incompat_log_feature(&mp->m_sb,
                                XFS_SB_FEAT_INCOMPAT_LOG_ALL)) {
                xfs_info(mp, "Clearing log incompat feature flags.");
                xfs_sb_remove_incompat_log_features(&mp->m_sb);
                ret = true;
        }

        xfs_buf_relse(mp->m_sb_bp);
        return ret;
}

/*
 * Update the in-core delayed block counter.
 *
 * We prefer to update the counter without having to take a spinlock for every
 * counter update (i.e. batching).  Each change to delayed allocation
 * reservations can change can easily exceed the default percpu counter
 * batching, so we use a larger batch factor here.
 *
 * Note that we don't currently have any callers requiring fast summation
 * (e.g. percpu_counter_read) so we can use a big batch value here.
 */
#define XFS_DELALLOC_BATCH      (4096)
void
xfs_mod_delalloc(
        struct xfs_mount        *mp,
        int64_t                 delta)
{
        percpu_counter_add_batch(&mp->m_delalloc_blks, delta,
                        XFS_DELALLOC_BATCH);
}