drm/atomic-helper: document drm_atomic_helper_check() restrictions

[drm/drm-misc.git] / fs / xfs / scrub / attr_repair.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (c) 2018-2024 Oracle.  All Rights Reserved.
 * Author: Darrick J. Wong <djwong@kernel.org>
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_defer.h"
#include "xfs_btree.h"
#include "xfs_bit.h"
#include "xfs_log_format.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_inode.h"
#include "xfs_da_format.h"
#include "xfs_da_btree.h"
#include "xfs_dir2.h"
#include "xfs_attr.h"
#include "xfs_attr_leaf.h"
#include "xfs_attr_sf.h"
#include "xfs_attr_remote.h"
#include "xfs_bmap.h"
#include "xfs_bmap_util.h"
#include "xfs_exchmaps.h"
#include "xfs_exchrange.h"
#include "xfs_acl.h"
#include "xfs_parent.h"
#include "scrub/xfs_scrub.h"
#include "scrub/scrub.h"
#include "scrub/common.h"
#include "scrub/trace.h"
#include "scrub/repair.h"
#include "scrub/tempfile.h"
#include "scrub/tempexch.h"
#include "scrub/xfile.h"
#include "scrub/xfarray.h"
#include "scrub/xfblob.h"
#include "scrub/attr.h"
#include "scrub/reap.h"
#include "scrub/attr_repair.h"

/*
 * Extended Attribute Repair
 * =========================
 *
 * We repair extended attributes by reading the attr leaf blocks looking for
 * attributes entries that look salvageable (name passes verifiers, value can
 * be retrieved, etc).  Each extended attribute worth salvaging is stashed in
 * memory, and the stashed entries are periodically replayed into a temporary
 * file to constrain memory use.  Batching the construction of the temporary
 * extended attribute structure in this fashion reduces lock cycling of the
 * file being repaired and the temporary file.
 *
 * When salvaging completes, the remaining stashed attributes are replayed to
 * the temporary file.  An atomic file contents exchange is used to commit the
 * new xattr blocks to the file being repaired.  This will disrupt attrmulti
 * cursors.
 */

struct xrep_xattr_key {
        /* Cookie for retrieval of the xattr name. */
        xfblob_cookie           name_cookie;

        /* Cookie for retrieval of the xattr value. */
        xfblob_cookie           value_cookie;

        /* XFS_ATTR_* flags */
        int                     flags;

        /* Length of the value and name. */
        uint32_t                valuelen;
        uint16_t                namelen;
};

/*
 * Stash up to 8 pages of attrs in xattr_records/xattr_blobs before we write
 * them to the temp file.
 */
#define XREP_XATTR_MAX_STASH_BYTES      (PAGE_SIZE * 8)

struct xrep_xattr {
        struct xfs_scrub        *sc;

        /* Information for exchanging attr fork mappings at the end. */
        struct xrep_tempexch    tx;

        /* xattr keys */
        struct xfarray          *xattr_records;

        /* xattr values */
        struct xfblob           *xattr_blobs;

        /* Number of attributes that we are salvaging. */
        unsigned long long      attrs_found;

        /* Can we flush stashed attrs to the tempfile? */
        bool                    can_flush;

        /* Did the live update fail, and hence the repair is now out of date? */
        bool                    live_update_aborted;

        /* Lock protecting parent pointer updates */
        struct mutex            lock;

        /* Fixed-size array of xrep_xattr_pptr structures. */
        struct xfarray          *pptr_recs;

        /* Blobs containing parent pointer names. */
        struct xfblob           *pptr_names;

        /* Hook to capture parent pointer updates. */
        struct xfs_dir_hook     dhook;

        /* Scratch buffer for capturing parent pointers. */
        struct xfs_da_args      pptr_args;

        /* Name buffer */
        struct xfs_name         xname;
        char                    namebuf[MAXNAMELEN];
};

/* Create a parent pointer in the tempfile. */
#define XREP_XATTR_PPTR_ADD     (1)

/* Remove a parent pointer from the tempfile. */
#define XREP_XATTR_PPTR_REMOVE  (2)

/* A stashed parent pointer update. */
struct xrep_xattr_pptr {
        /* Cookie for retrieval of the pptr name. */
        xfblob_cookie           name_cookie;

        /* Parent pointer record. */
        struct xfs_parent_rec   pptr_rec;

        /* Length of the pptr name. */
        uint8_t                 namelen;

        /* XREP_XATTR_PPTR_{ADD,REMOVE} */
        uint8_t                 action;
};

/* Set up to recreate the extended attributes. */
int
xrep_setup_xattr(
        struct xfs_scrub        *sc)
{
        if (xfs_has_parent(sc->mp))
                xchk_fsgates_enable(sc, XCHK_FSGATES_DIRENTS);

        return xrep_tempfile_create(sc, S_IFREG);
}

/*
 * Decide if we want to salvage this attribute.  We don't bother with
 * incomplete or oversized keys or values.  The @value parameter can be null
 * for remote attrs.
 */
STATIC int
xrep_xattr_want_salvage(
        struct xrep_xattr       *rx,
        unsigned int            attr_flags,
        const void              *name,
        int                     namelen,
        const void              *value,
        int                     valuelen)
{
        if (attr_flags & XFS_ATTR_INCOMPLETE)
                return false;
        if (namelen > XATTR_NAME_MAX || namelen <= 0)
                return false;
        if (!xfs_attr_namecheck(attr_flags, name, namelen))
                return false;
        if (valuelen > XATTR_SIZE_MAX || valuelen < 0)
                return false;
        if (attr_flags & XFS_ATTR_PARENT)
                return xfs_parent_valuecheck(rx->sc->mp, value, valuelen);

        return true;
}

/* Allocate an in-core record to hold xattrs while we rebuild the xattr data. */
STATIC int
xrep_xattr_salvage_key(
        struct xrep_xattr       *rx,
        int                     flags,
        unsigned char           *name,
        int                     namelen,
        unsigned char           *value,
        int                     valuelen)
{
        struct xrep_xattr_key   key = {
                .valuelen       = valuelen,
                .flags          = flags & XFS_ATTR_NSP_ONDISK_MASK,
        };
        unsigned int            i = 0;
        int                     error = 0;

        if (xchk_should_terminate(rx->sc, &error))
                return error;

        /*
         * Truncate the name to the first character that would trip namecheck.
         * If we no longer have a name after that, ignore this attribute.
         */
        if (flags & XFS_ATTR_PARENT) {
                key.namelen = namelen;

                trace_xrep_xattr_salvage_pptr(rx->sc->ip, flags, name,
                                key.namelen, value, valuelen);
        } else {
                while (i < namelen && name[i] != 0)
                        i++;
                if (i == 0)
                        return 0;
                key.namelen = i;

                trace_xrep_xattr_salvage_rec(rx->sc->ip, flags, name,
                                key.namelen, valuelen);
        }

        error = xfblob_store(rx->xattr_blobs, &key.name_cookie, name,
                        key.namelen);
        if (error)
                return error;

        error = xfblob_store(rx->xattr_blobs, &key.value_cookie, value,
                        key.valuelen);
        if (error)
                return error;

        error = xfarray_append(rx->xattr_records, &key);
        if (error)
                return error;

        rx->attrs_found++;
        return 0;
}

/*
 * Record a shortform extended attribute key & value for later reinsertion
 * into the inode.
 */
STATIC int
xrep_xattr_salvage_sf_attr(
        struct xrep_xattr               *rx,
        struct xfs_attr_sf_hdr          *hdr,
        struct xfs_attr_sf_entry        *sfe)
{
        struct xfs_scrub                *sc = rx->sc;
        struct xchk_xattr_buf           *ab = sc->buf;
        unsigned char                   *name = sfe->nameval;
        unsigned char                   *value = &sfe->nameval[sfe->namelen];

        if (!xchk_xattr_set_map(sc, ab->usedmap, (char *)name - (char *)hdr,
                        sfe->namelen))
                return 0;

        if (!xchk_xattr_set_map(sc, ab->usedmap, (char *)value - (char *)hdr,
                        sfe->valuelen))
                return 0;

        if (!xrep_xattr_want_salvage(rx, sfe->flags, sfe->nameval,
                        sfe->namelen, value, sfe->valuelen))
                return 0;

        return xrep_xattr_salvage_key(rx, sfe->flags, sfe->nameval,
                        sfe->namelen, value, sfe->valuelen);
}

/*
 * Record a local format extended attribute key & value for later reinsertion
 * into the inode.
 */
STATIC int
xrep_xattr_salvage_local_attr(
        struct xrep_xattr               *rx,
        struct xfs_attr_leaf_entry      *ent,
        unsigned int                    nameidx,
        const char                      *buf_end,
        struct xfs_attr_leaf_name_local *lentry)
{
        struct xchk_xattr_buf           *ab = rx->sc->buf;
        unsigned char                   *value;
        unsigned int                    valuelen;
        unsigned int                    namesize;

        /*
         * Decode the leaf local entry format.  If something seems wrong, we
         * junk the attribute.
         */
        value = &lentry->nameval[lentry->namelen];
        valuelen = be16_to_cpu(lentry->valuelen);
        namesize = xfs_attr_leaf_entsize_local(lentry->namelen, valuelen);
        if ((char *)lentry + namesize > buf_end)
                return 0;
        if (!xrep_xattr_want_salvage(rx, ent->flags, lentry->nameval,
                        lentry->namelen, value, valuelen))
                return 0;
        if (!xchk_xattr_set_map(rx->sc, ab->usedmap, nameidx, namesize))
                return 0;

        /* Try to save this attribute. */
        return xrep_xattr_salvage_key(rx, ent->flags, lentry->nameval,
                        lentry->namelen, value, valuelen);
}

/*
 * Record a remote format extended attribute key & value for later reinsertion
 * into the inode.
 */
STATIC int
xrep_xattr_salvage_remote_attr(
        struct xrep_xattr               *rx,
        struct xfs_attr_leaf_entry      *ent,
        unsigned int                    nameidx,
        const char                      *buf_end,
        struct xfs_attr_leaf_name_remote *rentry,
        unsigned int                    ent_idx,
        struct xfs_buf                  *leaf_bp)
{
        struct xchk_xattr_buf           *ab = rx->sc->buf;
        struct xfs_da_args              args = {
                .trans                  = rx->sc->tp,
                .dp                     = rx->sc->ip,
                .index                  = ent_idx,
                .geo                    = rx->sc->mp->m_attr_geo,
                .owner                  = rx->sc->ip->i_ino,
                .attr_filter            = ent->flags & XFS_ATTR_NSP_ONDISK_MASK,
                .namelen                = rentry->namelen,
                .name                   = rentry->name,
                .value                  = ab->value,
                .valuelen               = be32_to_cpu(rentry->valuelen),
        };
        unsigned int                    namesize;
        int                             error;

        /*
         * Decode the leaf remote entry format.  If something seems wrong, we
         * junk the attribute.  Note that we should never find a zero-length
         * remote attribute value.
         */
        namesize = xfs_attr_leaf_entsize_remote(rentry->namelen);
        if ((char *)rentry + namesize > buf_end)
                return 0;
        if (args.valuelen == 0 ||
            !xrep_xattr_want_salvage(rx, ent->flags, rentry->name,
                        rentry->namelen, NULL, args.valuelen))
                return 0;
        if (!xchk_xattr_set_map(rx->sc, ab->usedmap, nameidx, namesize))
                return 0;

        /*
         * Enlarge the buffer (if needed) to hold the value that we're trying
         * to salvage from the old extended attribute data.
         */
        error = xchk_setup_xattr_buf(rx->sc, args.valuelen);
        if (error == -ENOMEM)
                error = -EDEADLOCK;
        if (error)
                return error;

        /* Look up the remote value and stash it for reconstruction. */
        error = xfs_attr3_leaf_getvalue(leaf_bp, &args);
        if (error || args.rmtblkno == 0)
                goto err_free;

        error = xfs_attr_rmtval_get(&args);
        if (error)
                goto err_free;

        /* Try to save this attribute. */
        error = xrep_xattr_salvage_key(rx, ent->flags, rentry->name,
                        rentry->namelen, ab->value, args.valuelen);
err_free:
        /* remote value was garbage, junk it */
        if (error == -EFSBADCRC || error == -EFSCORRUPTED)
                error = 0;
        return error;
}

/* Extract every xattr key that we can from this attr fork block. */
STATIC int
xrep_xattr_recover_leaf(
        struct xrep_xattr               *rx,
        struct xfs_buf                  *bp)
{
        struct xfs_attr3_icleaf_hdr     leafhdr;
        struct xfs_scrub                *sc = rx->sc;
        struct xfs_mount                *mp = sc->mp;
        struct xfs_attr_leafblock       *leaf;
        struct xfs_attr_leaf_name_local *lentry;
        struct xfs_attr_leaf_name_remote *rentry;
        struct xfs_attr_leaf_entry      *ent;
        struct xfs_attr_leaf_entry      *entries;
        struct xchk_xattr_buf           *ab = rx->sc->buf;
        char                            *buf_end;
        size_t                          off;
        unsigned int                    nameidx;
        unsigned int                    hdrsize;
        int                             i;
        int                             error = 0;

        bitmap_zero(ab->usedmap, mp->m_attr_geo->blksize);

        /* Check the leaf header */
        leaf = bp->b_addr;
        xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &leafhdr, leaf);
        hdrsize = xfs_attr3_leaf_hdr_size(leaf);
        xchk_xattr_set_map(sc, ab->usedmap, 0, hdrsize);
        entries = xfs_attr3_leaf_entryp(leaf);

        buf_end = (char *)bp->b_addr + mp->m_attr_geo->blksize;
        for (i = 0, ent = entries; i < leafhdr.count; ent++, i++) {
                if (xchk_should_terminate(sc, &error))
                        return error;

                /* Skip key if it conflicts with something else? */
                off = (char *)ent - (char *)leaf;
                if (!xchk_xattr_set_map(sc, ab->usedmap, off,
                                sizeof(xfs_attr_leaf_entry_t)))
                        continue;

                /* Check the name information. */
                nameidx = be16_to_cpu(ent->nameidx);
                if (nameidx < leafhdr.firstused ||
                    nameidx >= mp->m_attr_geo->blksize)
                        continue;

                if (ent->flags & XFS_ATTR_LOCAL) {
                        lentry = xfs_attr3_leaf_name_local(leaf, i);
                        error = xrep_xattr_salvage_local_attr(rx, ent, nameidx,
                                        buf_end, lentry);
                } else {
                        rentry = xfs_attr3_leaf_name_remote(leaf, i);
                        error = xrep_xattr_salvage_remote_attr(rx, ent, nameidx,
                                        buf_end, rentry, i, bp);
                }
                if (error)
                        return error;
        }

        return 0;
}

/* Try to recover shortform attrs. */
STATIC int
xrep_xattr_recover_sf(
        struct xrep_xattr               *rx)
{
        struct xfs_scrub                *sc = rx->sc;
        struct xchk_xattr_buf           *ab = sc->buf;
        struct xfs_attr_sf_hdr          *hdr;
        struct xfs_attr_sf_entry        *sfe;
        struct xfs_attr_sf_entry        *next;
        struct xfs_ifork                *ifp;
        unsigned char                   *end;
        int                             i;
        int                             error = 0;

        ifp = xfs_ifork_ptr(rx->sc->ip, XFS_ATTR_FORK);
        hdr = ifp->if_data;

        bitmap_zero(ab->usedmap, ifp->if_bytes);
        end = (unsigned char *)ifp->if_data + ifp->if_bytes;
        xchk_xattr_set_map(sc, ab->usedmap, 0, sizeof(*hdr));

        sfe = xfs_attr_sf_firstentry(hdr);
        if ((unsigned char *)sfe > end)
                return 0;

        for (i = 0; i < hdr->count; i++) {
                if (xchk_should_terminate(sc, &error))
                        return error;

                next = xfs_attr_sf_nextentry(sfe);
                if ((unsigned char *)next > end)
                        break;

                if (xchk_xattr_set_map(sc, ab->usedmap,
                                (char *)sfe - (char *)hdr,
                                sizeof(struct xfs_attr_sf_entry))) {
                        /*
                         * No conflicts with the sf entry; let's save this
                         * attribute.
                         */
                        error = xrep_xattr_salvage_sf_attr(rx, hdr, sfe);
                        if (error)
                                return error;
                }

                sfe = next;
        }

        return 0;
}

/*
 * Try to return a buffer of xattr data for a given physical extent.
 *
 * Because the buffer cache get function complains if it finds a buffer
 * matching the block number but not matching the length, we must be careful to
 * look for incore buffers (up to the maximum length of a remote value) that
 * could be hiding anywhere in the physical range.  If we find an incore
 * buffer, we can pass that to the caller.  Optionally, read a single block and
 * pass that back.
 *
 * Note the subtlety that remote attr value blocks for which there is no incore
 * buffer will be passed to the callback one block at a time.  These buffers
 * will not have any ops attached and must be staled to prevent aliasing with
 * multiblock buffers once we drop the ILOCK.
 */
STATIC int
xrep_xattr_find_buf(
        struct xfs_mount        *mp,
        xfs_fsblock_t           fsbno,
        xfs_extlen_t            max_len,
        bool                    can_read,
        struct xfs_buf          **bpp)
{
        struct xrep_bufscan     scan = {
                .daddr          = XFS_FSB_TO_DADDR(mp, fsbno),
                .max_sectors    = xrep_bufscan_max_sectors(mp, max_len),
                .daddr_step     = XFS_FSB_TO_BB(mp, 1),
        };
        struct xfs_buf          *bp;

        while ((bp = xrep_bufscan_advance(mp, &scan)) != NULL) {
                *bpp = bp;
                return 0;
        }

        if (!can_read) {
                *bpp = NULL;
                return 0;
        }

        return xfs_buf_read(mp->m_ddev_targp, scan.daddr, XFS_FSB_TO_BB(mp, 1),
                        XBF_TRYLOCK, bpp, NULL);
}

/*
 * Deal with a buffer that we found during our walk of the attr fork.
 *
 * Attribute leaf and node blocks are simple -- they're a single block, so we
 * can walk them one at a time and we never have to worry about discontiguous
 * multiblock buffers like we do for directories.
 *
 * Unfortunately, remote attr blocks add a lot of complexity here.  Each disk
 * block is totally self contained, in the sense that the v5 header provides no
 * indication that there could be more data in the next block.  The incore
 * buffers can span multiple blocks, though they never cross extent records.
 * However, they don't necessarily start or end on an extent record boundary.
 * Therefore, we need a special buffer find function to walk the buffer cache
 * for us.
 *
 * The caller must hold the ILOCK on the file being repaired.  We use
 * XBF_TRYLOCK here to skip any locked buffer on the assumption that we don't
 * own the block and don't want to hang the system on a potentially garbage
 * buffer.
 */
STATIC int
xrep_xattr_recover_block(
        struct xrep_xattr       *rx,
        xfs_dablk_t             dabno,
        xfs_fsblock_t           fsbno,
        xfs_extlen_t            max_len,
        xfs_extlen_t            *actual_len)
{
        struct xfs_da_blkinfo   *info;
        struct xfs_buf          *bp;
        int                     error;

        error = xrep_xattr_find_buf(rx->sc->mp, fsbno, max_len, true, &bp);
        if (error)
                return error;
        info = bp->b_addr;
        *actual_len = XFS_BB_TO_FSB(rx->sc->mp, bp->b_length);

        trace_xrep_xattr_recover_leafblock(rx->sc->ip, dabno,
                        be16_to_cpu(info->magic));

        /*
         * If the buffer has the right magic number for an attr leaf block and
         * passes a structure check (we don't care about checksums), salvage
         * as much as we can from the block. */
        if (info->magic == cpu_to_be16(XFS_ATTR3_LEAF_MAGIC) &&
            xrep_buf_verify_struct(bp, &xfs_attr3_leaf_buf_ops) &&
            xfs_attr3_leaf_header_check(bp, rx->sc->ip->i_ino) == NULL)
                error = xrep_xattr_recover_leaf(rx, bp);

        /*
         * If the buffer didn't already have buffer ops set, it was read in by
         * the _find_buf function and could very well be /part/ of a multiblock
         * remote block.  Mark it stale so that it doesn't hang around in
         * memory to cause problems.
         */
        if (bp->b_ops == NULL)
                xfs_buf_stale(bp);

        xfs_buf_relse(bp);
        return error;
}

/* Insert one xattr key/value. */
STATIC int
xrep_xattr_insert_rec(
        struct xrep_xattr               *rx,
        const struct xrep_xattr_key     *key)
{
        struct xfs_da_args              args = {
                .dp                     = rx->sc->tempip,
                .attr_filter            = key->flags,
                .namelen                = key->namelen,
                .valuelen               = key->valuelen,
                .owner                  = rx->sc->ip->i_ino,
                .geo                    = rx->sc->mp->m_attr_geo,
                .whichfork              = XFS_ATTR_FORK,
                .op_flags               = XFS_DA_OP_OKNOENT,
        };
        struct xchk_xattr_buf           *ab = rx->sc->buf;
        int                             error;

        /*
         * Grab pointers to the scrub buffer so that we can use them to insert
         * attrs into the temp file.
         */
        args.name = ab->name;
        args.value = ab->value;

        /*
         * The attribute name is stored near the end of the in-core buffer,
         * though we reserve one more byte to ensure null termination.
         */
        ab->name[XATTR_NAME_MAX] = 0;

        error = xfblob_load(rx->xattr_blobs, key->name_cookie, ab->name,
                        key->namelen);
        if (error)
                return error;

        error = xfblob_free(rx->xattr_blobs, key->name_cookie);
        if (error)
                return error;

        error = xfblob_load(rx->xattr_blobs, key->value_cookie, args.value,
                        key->valuelen);
        if (error)
                return error;

        error = xfblob_free(rx->xattr_blobs, key->value_cookie);
        if (error)
                return error;

        ab->name[key->namelen] = 0;

        if (key->flags & XFS_ATTR_PARENT) {
                trace_xrep_xattr_insert_pptr(rx->sc->tempip, key->flags,
                                ab->name, key->namelen, ab->value,
                                key->valuelen);
                args.op_flags |= XFS_DA_OP_LOGGED;
        } else {
                trace_xrep_xattr_insert_rec(rx->sc->tempip, key->flags,
                                ab->name, key->namelen, key->valuelen);
        }

        /*
         * xfs_attr_set creates and commits its own transaction.  If the attr
         * already exists, we'll just drop it during the rebuild.
         */
        xfs_attr_sethash(&args);
        error = xfs_attr_set(&args, XFS_ATTRUPDATE_CREATE, false);
        if (error == -EEXIST)
                error = 0;

        return error;
}

/*
 * Periodically flush salvaged attributes to the temporary file.  This is done
 * to reduce the memory requirements of the xattr rebuild because files can
 * contain millions of attributes.
 */
STATIC int
xrep_xattr_flush_stashed(
        struct xrep_xattr       *rx)
{
        xfarray_idx_t           array_cur;
        int                     error;

        /*
         * Entering this function, the scrub context has a reference to the
         * inode being repaired, the temporary file, and a scrub transaction
         * that we use during xattr salvaging to avoid livelocking if there
         * are cycles in the xattr structures.  We hold ILOCK_EXCL on both
         * the inode being repaired, though it is not ijoined to the scrub
         * transaction.
         *
         * To constrain kernel memory use, we occasionally flush salvaged
         * xattrs from the xfarray and xfblob structures into the temporary
         * file in preparation for exchanging the xattr structures at the end.
         * Updating the temporary file requires a transaction, so we commit the
         * scrub transaction and drop the two ILOCKs so that xfs_attr_set can
         * allocate whatever transaction it wants.
         *
         * We still hold IOLOCK_EXCL on the inode being repaired, which
         * prevents anyone from modifying the damaged xattr data while we
         * repair it.
         */
        error = xrep_trans_commit(rx->sc);
        if (error)
                return error;
        xchk_iunlock(rx->sc, XFS_ILOCK_EXCL);

        /*
         * Take the IOLOCK of the temporary file while we modify xattrs.  This
         * isn't strictly required because the temporary file is never revealed
         * to userspace, but we follow the same locking rules.  We still hold
         * sc->ip's IOLOCK.
         */
        error = xrep_tempfile_iolock_polled(rx->sc);
        if (error)
                return error;

        /* Add all the salvaged attrs to the temporary file. */
        foreach_xfarray_idx(rx->xattr_records, array_cur) {
                struct xrep_xattr_key   key;

                error = xfarray_load(rx->xattr_records, array_cur, &key);
                if (error)
                        return error;

                error = xrep_xattr_insert_rec(rx, &key);
                if (error)
                        return error;
        }

        /* Empty out both arrays now that we've added the entries. */
        xfarray_truncate(rx->xattr_records);
        xfblob_truncate(rx->xattr_blobs);

        xrep_tempfile_iounlock(rx->sc);

        /* Recreate the salvage transaction and relock the inode. */
        error = xchk_trans_alloc(rx->sc, 0);
        if (error)
                return error;
        xchk_ilock(rx->sc, XFS_ILOCK_EXCL);
        return 0;
}

/* Decide if we've stashed too much xattr data in memory. */
static inline bool
xrep_xattr_want_flush_stashed(
        struct xrep_xattr       *rx)
{
        unsigned long long      bytes;

        if (!rx->can_flush)
                return false;

        bytes = xfarray_bytes(rx->xattr_records) +
                xfblob_bytes(rx->xattr_blobs);
        return bytes > XREP_XATTR_MAX_STASH_BYTES;
}

/*
 * Did we observe rename changing parent pointer xattrs while we were flushing
 * salvaged attrs?
 */
static inline bool
xrep_xattr_saw_pptr_conflict(
        struct xrep_xattr       *rx)
{
        bool                    ret;

        ASSERT(rx->can_flush);

        if (!xfs_has_parent(rx->sc->mp))
                return false;

        xfs_assert_ilocked(rx->sc->ip, XFS_ILOCK_EXCL);

        mutex_lock(&rx->lock);
        ret = xfarray_bytes(rx->pptr_recs) > 0;
        mutex_unlock(&rx->lock);

        return ret;
}

/*
 * Reset the entire repair state back to initial conditions, now that we've
 * detected a parent pointer update to the attr structure while we were
 * flushing salvaged attrs.  See the locking notes in dir_repair.c for more
 * information on why this is all necessary.
 */
STATIC int
xrep_xattr_full_reset(
        struct xrep_xattr       *rx)
{
        struct xfs_scrub        *sc = rx->sc;
        struct xfs_attr_sf_hdr  *hdr;
        struct xfs_ifork        *ifp = &sc->tempip->i_af;
        int                     error;

        trace_xrep_xattr_full_reset(sc->ip, sc->tempip);

        /* The temporary file's data fork had better not be in btree format. */
        if (sc->tempip->i_df.if_format == XFS_DINODE_FMT_BTREE) {
                ASSERT(0);
                return -EIO;
        }

        /*
         * We begin in transaction context with sc->ip ILOCKed but not joined
         * to the transaction.  To reset to the initial state, we must hold
         * sc->ip's ILOCK to prevent rename from updating parent pointer
         * information and the tempfile's ILOCK to clear its contents.
         */
        xchk_iunlock(rx->sc, XFS_ILOCK_EXCL);
        xrep_tempfile_ilock_both(sc);
        xfs_trans_ijoin(sc->tp, sc->ip, 0);
        xfs_trans_ijoin(sc->tp, sc->tempip, 0);

        /*
         * Free all the blocks of the attr fork of the temp file, and reset
         * it back to local format.
         */
        if (xfs_ifork_has_extents(&sc->tempip->i_af)) {
                error = xrep_reap_ifork(sc, sc->tempip, XFS_ATTR_FORK);
                if (error)
                        return error;

                ASSERT(ifp->if_bytes == 0);
                ifp->if_format = XFS_DINODE_FMT_LOCAL;
                xfs_idata_realloc(sc->tempip, sizeof(*hdr), XFS_ATTR_FORK);
        }

        /* Reinitialize the attr fork to an empty shortform structure. */
        hdr = ifp->if_data;
        memset(hdr, 0, sizeof(*hdr));
        hdr->totsize = cpu_to_be16(sizeof(*hdr));
        xfs_trans_log_inode(sc->tp, sc->tempip, XFS_ILOG_CORE | XFS_ILOG_ADATA);

        /*
         * Roll this transaction to commit our reset ondisk.  The tempfile
         * should no longer be joined to the transaction, so we drop its ILOCK.
         * This should leave us in transaction context with sc->ip ILOCKed but
         * not joined to the transaction.
         */
        error = xrep_roll_trans(sc);
        if (error)
                return error;
        xrep_tempfile_iunlock(sc);

        /*
         * Erase any accumulated parent pointer updates now that we've erased
         * the tempfile's attr fork.  We're resetting the entire repair state
         * back to where we were initially, except now we won't flush salvaged
         * xattrs until the very end.
         */
        mutex_lock(&rx->lock);
        xfarray_truncate(rx->pptr_recs);
        xfblob_truncate(rx->pptr_names);
        mutex_unlock(&rx->lock);

        rx->can_flush = false;
        rx->attrs_found = 0;

        ASSERT(xfarray_bytes(rx->xattr_records) == 0);
        ASSERT(xfblob_bytes(rx->xattr_blobs) == 0);
        return 0;
}

/* Extract as many attribute keys and values as we can. */
STATIC int
xrep_xattr_recover(
        struct xrep_xattr       *rx)
{
        struct xfs_bmbt_irec    got;
        struct xfs_scrub        *sc = rx->sc;
        struct xfs_da_geometry  *geo = sc->mp->m_attr_geo;
        xfs_fileoff_t           offset;
        xfs_extlen_t            len;
        xfs_dablk_t             dabno;
        int                     nmap;
        int                     error;

restart:
        /*
         * Iterate each xattr leaf block in the attr fork to scan them for any
         * attributes that we might salvage.
         */
        for (offset = 0;
             offset < XFS_MAX_FILEOFF;
             offset = got.br_startoff + got.br_blockcount) {
                nmap = 1;
                error = xfs_bmapi_read(sc->ip, offset, XFS_MAX_FILEOFF - offset,
                                &got, &nmap, XFS_BMAPI_ATTRFORK);
                if (error)
                        return error;
                if (nmap != 1)
                        return -EFSCORRUPTED;
                if (!xfs_bmap_is_written_extent(&got))
                        continue;

                for (dabno = round_up(got.br_startoff, geo->fsbcount);
                     dabno < got.br_startoff + got.br_blockcount;
                     dabno += len) {
                        xfs_fileoff_t   curr_offset = dabno - got.br_startoff;
                        xfs_extlen_t    maxlen;

                        if (xchk_should_terminate(rx->sc, &error))
                                return error;

                        maxlen = min_t(xfs_filblks_t, INT_MAX,
                                        got.br_blockcount - curr_offset);
                        error = xrep_xattr_recover_block(rx, dabno,
                                        curr_offset + got.br_startblock,
                                        maxlen, &len);
                        if (error)
                                return error;

                        if (xrep_xattr_want_flush_stashed(rx)) {
                                error = xrep_xattr_flush_stashed(rx);
                                if (error)
                                        return error;

                                if (xrep_xattr_saw_pptr_conflict(rx)) {
                                        error = xrep_xattr_full_reset(rx);
                                        if (error)
                                                return error;

                                        goto restart;
                                }
                        }
                }
        }

        return 0;
}

/*
 * Reset the extended attribute fork to a state where we can start re-adding
 * the salvaged attributes.
 */
STATIC int
xrep_xattr_fork_remove(
        struct xfs_scrub        *sc,
        struct xfs_inode        *ip)
{
        struct xfs_attr_sf_hdr  *hdr;
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, XFS_ATTR_FORK);

        /*
         * If the data fork is in btree format, we can't change di_forkoff
         * because we could run afoul of the rule that the data fork isn't
         * supposed to be in btree format if there's enough space in the fork
         * that it could have used extents format.  Instead, reinitialize the
         * attr fork to have a shortform structure with zero attributes.
         */
        if (ip->i_df.if_format == XFS_DINODE_FMT_BTREE) {
                ifp->if_format = XFS_DINODE_FMT_LOCAL;
                hdr = xfs_idata_realloc(ip, (int)sizeof(*hdr) - ifp->if_bytes,
                                XFS_ATTR_FORK);
                hdr->count = 0;
                hdr->totsize = cpu_to_be16(sizeof(*hdr));
                xfs_trans_log_inode(sc->tp, ip,
                                XFS_ILOG_CORE | XFS_ILOG_ADATA);
                return 0;
        }

        /* If we still have attr fork extents, something's wrong. */
        if (ifp->if_nextents != 0) {
                struct xfs_iext_cursor  icur;
                struct xfs_bmbt_irec    irec;
                unsigned int            i = 0;

                xfs_emerg(sc->mp,
        "inode 0x%llx attr fork still has %llu attr extents, format %d?!",
                                ip->i_ino, ifp->if_nextents, ifp->if_format);
                for_each_xfs_iext(ifp, &icur, &irec) {
                        xfs_err(sc->mp,
        "[%u]: startoff %llu startblock %llu blockcount %llu state %u",
                                        i++, irec.br_startoff,
                                        irec.br_startblock, irec.br_blockcount,
                                        irec.br_state);
                }
                ASSERT(0);
                return -EFSCORRUPTED;
        }

        xfs_attr_fork_remove(ip, sc->tp);
        return 0;
}

/*
 * Free all the attribute fork blocks of the file being repaired and delete the
 * fork.  The caller must ILOCK the scrub file and join it to the transaction.
 * This function returns with the inode joined to a clean transaction.
 */
int
xrep_xattr_reset_fork(
        struct xfs_scrub        *sc)
{
        int                     error;

        trace_xrep_xattr_reset_fork(sc->ip, sc->ip);

        /* Unmap all the attr blocks. */
        if (xfs_ifork_has_extents(&sc->ip->i_af)) {
                error = xrep_reap_ifork(sc, sc->ip, XFS_ATTR_FORK);
                if (error)
                        return error;
        }

        error = xrep_xattr_fork_remove(sc, sc->ip);
        if (error)
                return error;

        return xfs_trans_roll_inode(&sc->tp, sc->ip);
}

/*
 * Free all the attribute fork blocks of the temporary file and delete the attr
 * fork.  The caller must ILOCK the tempfile and join it to the transaction.
 * This function returns with the inode joined to a clean scrub transaction.
 */
int
xrep_xattr_reset_tempfile_fork(
        struct xfs_scrub        *sc)
{
        int                     error;

        trace_xrep_xattr_reset_fork(sc->ip, sc->tempip);

        /*
         * Wipe out the attr fork of the temp file so that regular inode
         * inactivation won't trip over the corrupt attr fork.
         */
        if (xfs_ifork_has_extents(&sc->tempip->i_af)) {
                error = xrep_reap_ifork(sc, sc->tempip, XFS_ATTR_FORK);
                if (error)
                        return error;
        }

        return xrep_xattr_fork_remove(sc, sc->tempip);
}

/*
 * Find all the extended attributes for this inode by scraping them out of the
 * attribute key blocks by hand, and flushing them into the temp file.
 * When we're done, free the staging memory before exchanging the xattr
 * structures to reduce memory usage.
 */
STATIC int
xrep_xattr_salvage_attributes(
        struct xrep_xattr       *rx)
{
        struct xfs_inode        *ip = rx->sc->ip;
        int                     error;

        /* Short format xattrs are easy! */
        if (rx->sc->ip->i_af.if_format == XFS_DINODE_FMT_LOCAL) {
                error = xrep_xattr_recover_sf(rx);
                if (error)
                        return error;

                return xrep_xattr_flush_stashed(rx);
        }

        /*
         * For non-inline xattr structures, the salvage function scans the
         * buffer cache looking for potential attr leaf blocks.  The scan
         * requires the ability to lock any buffer found and runs independently
         * of any transaction <-> buffer item <-> buffer linkage.  Therefore,
         * roll the transaction to ensure there are no buffers joined.  We hold
         * the ILOCK independently of the transaction.
         */
        error = xfs_trans_roll(&rx->sc->tp);
        if (error)
                return error;

        error = xfs_iread_extents(rx->sc->tp, ip, XFS_ATTR_FORK);
        if (error)
                return error;

        error = xrep_xattr_recover(rx);
        if (error)
                return error;

        return xrep_xattr_flush_stashed(rx);
}

/*
 * Add this stashed incore parent pointer to the temporary file.  The caller
 * must hold the tempdir's IOLOCK, must not hold any ILOCKs, and must not be in
 * transaction context.
 */
STATIC int
xrep_xattr_replay_pptr_update(
        struct xrep_xattr               *rx,
        const struct xfs_name           *xname,
        struct xrep_xattr_pptr          *pptr)
{
        struct xfs_scrub                *sc = rx->sc;
        int                             error;

        switch (pptr->action) {
        case XREP_XATTR_PPTR_ADD:
                /* Create parent pointer. */
                trace_xrep_xattr_replay_parentadd(sc->tempip, xname,
                                &pptr->pptr_rec);

                error = xfs_parent_set(sc->tempip, sc->ip->i_ino, xname,
                                &pptr->pptr_rec, &rx->pptr_args);
                ASSERT(error != -EEXIST);
                return error;
        case XREP_XATTR_PPTR_REMOVE:
                /* Remove parent pointer. */
                trace_xrep_xattr_replay_parentremove(sc->tempip, xname,
                                &pptr->pptr_rec);

                error = xfs_parent_unset(sc->tempip, sc->ip->i_ino, xname,
                                &pptr->pptr_rec, &rx->pptr_args);
                ASSERT(error != -ENOATTR);
                return error;
        }

        ASSERT(0);
        return -EIO;
}

/*
 * Flush stashed parent pointer updates that have been recorded by the scanner.
 * This is done to reduce the memory requirements of the xattr rebuild, since
 * files can have a lot of hardlinks and the fs can be busy.
 *
 * Caller must not hold transactions or ILOCKs.  Caller must hold the tempfile
 * IOLOCK.
 */
STATIC int
xrep_xattr_replay_pptr_updates(
        struct xrep_xattr       *rx)
{
        xfarray_idx_t           array_cur;
        int                     error;

        mutex_lock(&rx->lock);
        foreach_xfarray_idx(rx->pptr_recs, array_cur) {
                struct xrep_xattr_pptr  pptr;

                error = xfarray_load(rx->pptr_recs, array_cur, &pptr);
                if (error)
                        goto out_unlock;

                error = xfblob_loadname(rx->pptr_names, pptr.name_cookie,
                                &rx->xname, pptr.namelen);
                if (error)
                        goto out_unlock;
                mutex_unlock(&rx->lock);

                error = xrep_xattr_replay_pptr_update(rx, &rx->xname, &pptr);
                if (error)
                        return error;

                mutex_lock(&rx->lock);
        }

        /* Empty out both arrays now that we've added the entries. */
        xfarray_truncate(rx->pptr_recs);
        xfblob_truncate(rx->pptr_names);
        mutex_unlock(&rx->lock);
        return 0;
out_unlock:
        mutex_unlock(&rx->lock);
        return error;
}

/*
 * Remember that we want to create a parent pointer in the tempfile.  These
 * stashed actions will be replayed later.
 */
STATIC int
xrep_xattr_stash_parentadd(
        struct xrep_xattr       *rx,
        const struct xfs_name   *name,
        const struct xfs_inode  *dp)
{
        struct xrep_xattr_pptr  pptr = {
                .action         = XREP_XATTR_PPTR_ADD,
                .namelen        = name->len,
        };
        int                     error;

        trace_xrep_xattr_stash_parentadd(rx->sc->tempip, dp, name);

        xfs_inode_to_parent_rec(&pptr.pptr_rec, dp);
        error = xfblob_storename(rx->pptr_names, &pptr.name_cookie, name);
        if (error)
                return error;

        return xfarray_append(rx->pptr_recs, &pptr);
}

/*
 * Remember that we want to remove a parent pointer from the tempfile.  These
 * stashed actions will be replayed later.
 */
STATIC int
xrep_xattr_stash_parentremove(
        struct xrep_xattr       *rx,
        const struct xfs_name   *name,
        const struct xfs_inode  *dp)
{
        struct xrep_xattr_pptr  pptr = {
                .action         = XREP_XATTR_PPTR_REMOVE,
                .namelen        = name->len,
        };
        int                     error;

        trace_xrep_xattr_stash_parentremove(rx->sc->tempip, dp, name);

        xfs_inode_to_parent_rec(&pptr.pptr_rec, dp);
        error = xfblob_storename(rx->pptr_names, &pptr.name_cookie, name);
        if (error)
                return error;

        return xfarray_append(rx->pptr_recs, &pptr);
}

/*
 * Capture dirent updates being made by other threads.  We will have to replay
 * the parent pointer updates before exchanging attr forks.
 */
STATIC int
xrep_xattr_live_dirent_update(
        struct notifier_block           *nb,
        unsigned long                   action,
        void                            *data)
{
        struct xfs_dir_update_params    *p = data;
        struct xrep_xattr               *rx;
        struct xfs_scrub                *sc;
        int                             error;

        rx = container_of(nb, struct xrep_xattr, dhook.dirent_hook.nb);
        sc = rx->sc;

        /*
         * This thread updated a dirent that points to the file that we're
         * repairing, so stash the update for replay against the temporary
         * file.
         */
        if (p->ip->i_ino != sc->ip->i_ino)
                return NOTIFY_DONE;

        mutex_lock(&rx->lock);
        if (p->delta > 0)
                error = xrep_xattr_stash_parentadd(rx, p->name, p->dp);
        else
                error = xrep_xattr_stash_parentremove(rx, p->name, p->dp);
        if (error)
                rx->live_update_aborted = true;
        mutex_unlock(&rx->lock);
        return NOTIFY_DONE;
}

/*
 * Prepare both inodes' attribute forks for an exchange.  Promote the tempfile
 * from short format to leaf format, and if the file being repaired has a short
 * format attr fork, turn it into an empty extent list.
 */
STATIC int
xrep_xattr_swap_prep(
        struct xfs_scrub        *sc,
        bool                    temp_local,
        bool                    ip_local)
{
        int                     error;

        /*
         * If the tempfile's attributes are in shortform format, convert that
         * to a single leaf extent so that we can use the atomic mapping
         * exchange.
         */
        if (temp_local) {
                struct xfs_da_args      args = {
                        .dp             = sc->tempip,
                        .geo            = sc->mp->m_attr_geo,
                        .whichfork      = XFS_ATTR_FORK,
                        .trans          = sc->tp,
                        .total          = 1,
                        .owner          = sc->ip->i_ino,
                };

                error = xfs_attr_shortform_to_leaf(&args);
                if (error)
                        return error;

                /*
                 * Roll the deferred log items to get us back to a clean
                 * transaction.
                 */
                error = xfs_defer_finish(&sc->tp);
                if (error)
                        return error;
        }

        /*
         * If the file being repaired had a shortform attribute fork, convert
         * that to an empty extent list in preparation for the atomic mapping
         * exchange.
         */
        if (ip_local) {
                struct xfs_ifork        *ifp;

                ifp = xfs_ifork_ptr(sc->ip, XFS_ATTR_FORK);

                xfs_idestroy_fork(ifp);
                ifp->if_format = XFS_DINODE_FMT_EXTENTS;
                ifp->if_nextents = 0;
                ifp->if_bytes = 0;
                ifp->if_data = NULL;
                ifp->if_height = 0;

                xfs_trans_log_inode(sc->tp, sc->ip,
                                XFS_ILOG_CORE | XFS_ILOG_ADATA);
        }

        return 0;
}

/* Exchange the temporary file's attribute fork with the one being repaired. */
int
xrep_xattr_swap(
        struct xfs_scrub        *sc,
        struct xrep_tempexch    *tx)
{
        bool                    ip_local, temp_local;
        int                     error = 0;

        ip_local = sc->ip->i_af.if_format == XFS_DINODE_FMT_LOCAL;
        temp_local = sc->tempip->i_af.if_format == XFS_DINODE_FMT_LOCAL;

        /*
         * If the both files have a local format attr fork and the rebuilt
         * xattr data would fit in the repaired file's attr fork, just copy
         * the contents from the tempfile and declare ourselves done.
         */
        if (ip_local && temp_local) {
                int     forkoff;
                int     newsize;

                newsize = xfs_attr_sf_totsize(sc->tempip);
                forkoff = xfs_attr_shortform_bytesfit(sc->ip, newsize);
                if (forkoff > 0) {
                        sc->ip->i_forkoff = forkoff;
                        xrep_tempfile_copyout_local(sc, XFS_ATTR_FORK);
                        return 0;
                }
        }

        /* Otherwise, make sure both attr forks are in block-mapping mode. */
        error = xrep_xattr_swap_prep(sc, temp_local, ip_local);
        if (error)
                return error;

        return xrep_tempexch_contents(sc, tx);
}

/*
 * Finish replaying stashed parent pointer updates, allocate a transaction for
 * exchanging extent mappings, and take the ILOCKs of both files before we
 * commit the new extended attribute structure.
 */
STATIC int
xrep_xattr_finalize_tempfile(
        struct xrep_xattr       *rx)
{
        struct xfs_scrub        *sc = rx->sc;
        int                     error;

        if (!xfs_has_parent(sc->mp))
                return xrep_tempexch_trans_alloc(sc, XFS_ATTR_FORK, &rx->tx);

        /*
         * Repair relies on the ILOCK to quiesce all possible xattr updates.
         * Replay all queued parent pointer updates into the tempfile before
         * exchanging the contents, even if that means dropping the ILOCKs and
         * the transaction.
         */
        do {
                error = xrep_xattr_replay_pptr_updates(rx);
                if (error)
                        return error;

                error = xrep_tempexch_trans_alloc(sc, XFS_ATTR_FORK, &rx->tx);
                if (error)
                        return error;

                if (xfarray_length(rx->pptr_recs) == 0)
                        break;

                xchk_trans_cancel(sc);
                xrep_tempfile_iunlock_both(sc);
        } while (!xchk_should_terminate(sc, &error));
        return error;
}

/*
 * Exchange the new extended attribute data (which we created in the tempfile)
 * with the file being repaired.
 */
STATIC int
xrep_xattr_rebuild_tree(
        struct xrep_xattr       *rx)
{
        struct xfs_scrub        *sc = rx->sc;
        int                     error;

        /*
         * If we didn't find any attributes to salvage, repair the file by
         * zapping its attr fork.
         */
        if (rx->attrs_found == 0) {
                xfs_trans_ijoin(sc->tp, sc->ip, 0);
                error = xrep_xattr_reset_fork(sc);
                if (error)
                        return error;

                goto forget_acls;
        }

        trace_xrep_xattr_rebuild_tree(sc->ip, sc->tempip);

        /*
         * Commit the repair transaction and drop the ILOCKs so that we can use
         * the atomic file content exchange helper functions to compute the
         * correct resource reservations.
         *
         * We still hold IOLOCK_EXCL (aka i_rwsem) which will prevent xattr
         * modifications, but there's nothing to prevent userspace from reading
         * the attributes until we're ready for the exchange operation.  Reads
         * will return -EIO without shutting down the fs, so we're ok with
         * that.
         */
        error = xrep_trans_commit(sc);
        if (error)
                return error;

        xchk_iunlock(sc, XFS_ILOCK_EXCL);

        /*
         * Take the IOLOCK on the temporary file so that we can run xattr
         * operations with the same locks held as we would for a normal file.
         * We still hold sc->ip's IOLOCK.
         */
        error = xrep_tempfile_iolock_polled(rx->sc);
        if (error)
                return error;

        /*
         * Allocate transaction, lock inodes, and make sure that we've replayed
         * all the stashed parent pointer updates to the temp file.  After this
         * point, we're ready to exchange attr fork mappings.
         */
        error = xrep_xattr_finalize_tempfile(rx);
        if (error)
                return error;

        /*
         * Exchange the blocks mapped by the tempfile's attr fork with the file
         * being repaired.  The old attr blocks will then be attached to the
         * tempfile, so reap its attr fork.
         */
        error = xrep_xattr_swap(sc, &rx->tx);
        if (error)
                return error;

        error = xrep_xattr_reset_tempfile_fork(sc);
        if (error)
                return error;

        /*
         * Roll to get a transaction without any inodes joined to it.  Then we
         * can drop the tempfile's ILOCK and IOLOCK before doing more work on
         * the scrub target file.
         */
        error = xfs_trans_roll(&sc->tp);
        if (error)
                return error;

        xrep_tempfile_iunlock(sc);
        xrep_tempfile_iounlock(sc);

forget_acls:
        /* Invalidate cached ACLs now that we've reloaded all the xattrs. */
        xfs_forget_acl(VFS_I(sc->ip), SGI_ACL_FILE);
        xfs_forget_acl(VFS_I(sc->ip), SGI_ACL_DEFAULT);
        return 0;
}

/* Tear down all the incore scan stuff we created. */
STATIC void
xrep_xattr_teardown(
        struct xrep_xattr       *rx)
{
        if (xfs_has_parent(rx->sc->mp))
                xfs_dir_hook_del(rx->sc->mp, &rx->dhook);
        if (rx->pptr_names)
                xfblob_destroy(rx->pptr_names);
        if (rx->pptr_recs)
                xfarray_destroy(rx->pptr_recs);
        xfblob_destroy(rx->xattr_blobs);
        xfarray_destroy(rx->xattr_records);
        mutex_destroy(&rx->lock);
        kfree(rx);
}

/* Set up the filesystem scan so we can regenerate extended attributes. */
STATIC int
xrep_xattr_setup_scan(
        struct xfs_scrub        *sc,
        struct xrep_xattr       **rxp)
{
        struct xrep_xattr       *rx;
        char                    *descr;
        int                     max_len;
        int                     error;

        rx = kzalloc(sizeof(struct xrep_xattr), XCHK_GFP_FLAGS);
        if (!rx)
                return -ENOMEM;
        rx->sc = sc;
        rx->can_flush = true;
        rx->xname.name = rx->namebuf;

        mutex_init(&rx->lock);

        /*
         * Allocate enough memory to handle loading local attr values from the
         * xfblob data while flushing stashed attrs to the temporary file.
         * We only realloc the buffer when salvaging remote attr values.
         */
        max_len = xfs_attr_leaf_entsize_local_max(sc->mp->m_attr_geo->blksize);
        error = xchk_setup_xattr_buf(rx->sc, max_len);
        if (error == -ENOMEM)
                error = -EDEADLOCK;
        if (error)
                goto out_rx;

        /* Set up some staging for salvaged attribute keys and values */
        descr = xchk_xfile_ino_descr(sc, "xattr keys");
        error = xfarray_create(descr, 0, sizeof(struct xrep_xattr_key),
                        &rx->xattr_records);
        kfree(descr);
        if (error)
                goto out_rx;

        descr = xchk_xfile_ino_descr(sc, "xattr names");
        error = xfblob_create(descr, &rx->xattr_blobs);
        kfree(descr);
        if (error)
                goto out_keys;

        if (xfs_has_parent(sc->mp)) {
                ASSERT(sc->flags & XCHK_FSGATES_DIRENTS);

                descr = xchk_xfile_ino_descr(sc,
                                "xattr retained parent pointer entries");
                error = xfarray_create(descr, 0,
                                sizeof(struct xrep_xattr_pptr),
                                &rx->pptr_recs);
                kfree(descr);
                if (error)
                        goto out_values;

                descr = xchk_xfile_ino_descr(sc,
                                "xattr retained parent pointer names");
                error = xfblob_create(descr, &rx->pptr_names);
                kfree(descr);
                if (error)
                        goto out_pprecs;

                xfs_dir_hook_setup(&rx->dhook, xrep_xattr_live_dirent_update);
                error = xfs_dir_hook_add(sc->mp, &rx->dhook);
                if (error)
                        goto out_ppnames;
        }

        *rxp = rx;
        return 0;
out_ppnames:
        xfblob_destroy(rx->pptr_names);
out_pprecs:
        xfarray_destroy(rx->pptr_recs);
out_values:
        xfblob_destroy(rx->xattr_blobs);
out_keys:
        xfarray_destroy(rx->xattr_records);
out_rx:
        mutex_destroy(&rx->lock);
        kfree(rx);
        return error;
}

/*
 * Repair the extended attribute metadata.
 *
 * XXX: Remote attribute value buffers encompass the entire (up to 64k) buffer.
 * The buffer cache in XFS can't handle aliased multiblock buffers, so this
 * might misbehave if the attr fork is crosslinked with other filesystem
 * metadata.
 */
int
xrep_xattr(
        struct xfs_scrub        *sc)
{
        struct xrep_xattr       *rx = NULL;
        int                     error;

        if (!xfs_inode_hasattr(sc->ip))
                return -ENOENT;

        /* The rmapbt is required to reap the old attr fork. */
        if (!xfs_has_rmapbt(sc->mp))
                return -EOPNOTSUPP;
        /* We require atomic file exchange range to rebuild anything. */
        if (!xfs_has_exchange_range(sc->mp))
                return -EOPNOTSUPP;

        error = xrep_xattr_setup_scan(sc, &rx);
        if (error)
                return error;

        ASSERT(sc->ilock_flags & XFS_ILOCK_EXCL);

        error = xrep_xattr_salvage_attributes(rx);
        if (error)
                goto out_scan;

        if (rx->live_update_aborted) {
                error = -EIO;
                goto out_scan;
        }

        /* Last chance to abort before we start committing fixes. */
        if (xchk_should_terminate(sc, &error))
                goto out_scan;

        error = xrep_xattr_rebuild_tree(rx);
        if (error)
                goto out_scan;

out_scan:
        xrep_xattr_teardown(rx);
        return error;
}