xfs: allocate xattr buffer on demand

[thirdparty/xfsprogs-dev.git] / libxfs / xfs_attr.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 */
#include "libxfs_priv.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_mount.h"
#include "xfs_defer.h"
#include "xfs_da_format.h"
#include "xfs_da_btree.h"
#include "xfs_attr_sf.h"
#include "xfs_inode.h"
#include "xfs_trans.h"
#include "xfs_bmap.h"
#include "xfs_bmap_btree.h"
#include "xfs_attr.h"
#include "xfs_attr_leaf.h"
#include "xfs_attr_remote.h"
#include "xfs_trans_space.h"
#include "xfs_trace.h"

/*
 * xfs_attr.c
 *
 * Provide the external interfaces to manage attribute lists.
 */

/*========================================================================
 * Function prototypes for the kernel.
 *========================================================================*/

/*
 * Internal routines when attribute list fits inside the inode.
 */
STATIC int xfs_attr_shortform_addname(xfs_da_args_t *args);

/*
 * Internal routines when attribute list is one block.
 */
STATIC int xfs_attr_leaf_get(xfs_da_args_t *args);
STATIC int xfs_attr_leaf_addname(xfs_da_args_t *args);
STATIC int xfs_attr_leaf_removename(xfs_da_args_t *args);

/*
 * Internal routines when attribute list is more than one block.
 */
STATIC int xfs_attr_node_get(xfs_da_args_t *args);
STATIC int xfs_attr_node_addname(xfs_da_args_t *args);
STATIC int xfs_attr_node_removename(xfs_da_args_t *args);
STATIC int xfs_attr_fillstate(xfs_da_state_t *state);
STATIC int xfs_attr_refillstate(xfs_da_state_t *state);


STATIC int
xfs_attr_args_init(
        struct xfs_da_args      *args,
        struct xfs_inode        *dp,
        const unsigned char     *name,
        int                     flags)
{

        if (!name)
                return -EINVAL;

        memset(args, 0, sizeof(*args));
        args->geo = dp->i_mount->m_attr_geo;
        args->whichfork = XFS_ATTR_FORK;
        args->dp = dp;
        args->flags = flags;
        args->name = name;
        args->namelen = strlen((const char *)name);
        if (args->namelen >= MAXNAMELEN)
                return -EFAULT;         /* match IRIX behaviour */

        args->hashval = xfs_da_hashname(args->name, args->namelen);
        return 0;
}

int
xfs_inode_hasattr(
        struct xfs_inode        *ip)
{
        if (!XFS_IFORK_Q(ip) ||
            (ip->i_d.di_aformat == XFS_DINODE_FMT_EXTENTS &&
             ip->i_d.di_anextents == 0))
                return 0;
        return 1;
}

/*========================================================================
 * Overall external interface routines.
 *========================================================================*/

/*
 * Retrieve an extended attribute and its value.  Must have ilock.
 * Returns 0 on successful retrieval, otherwise an error.
 */
int
xfs_attr_get_ilocked(
        struct xfs_inode        *ip,
        struct xfs_da_args      *args)
{
        ASSERT(xfs_isilocked(ip, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));

        if (!xfs_inode_hasattr(ip))
                return -ENOATTR;
        else if (ip->i_d.di_aformat == XFS_DINODE_FMT_LOCAL)
                return xfs_attr_shortform_getvalue(args);
        else if (xfs_bmap_one_block(ip, XFS_ATTR_FORK))
                return xfs_attr_leaf_get(args);
        else
                return xfs_attr_node_get(args);
}

/*
 * Retrieve an extended attribute by name, and its value if requested.
 *
 * If ATTR_KERNOVAL is set in @flags, then the caller does not want the value,
 * just an indication whether the attribute exists and the size of the value if
 * it exists. The size is returned in @valuelenp,
 *
 * If the attribute is found, but exceeds the size limit set by the caller in
 * @valuelenp, return -ERANGE with the size of the attribute that was found in
 * @valuelenp.
 *
 * If ATTR_ALLOC is set in @flags, allocate the buffer for the value after
 * existence of the attribute has been determined. On success, return that
 * buffer to the caller and leave them to free it. On failure, free any
 * allocated buffer and ensure the buffer pointer returned to the caller is
 * null.
 */
int
xfs_attr_get(
        struct xfs_inode        *ip,
        const unsigned char     *name,
        unsigned char           **value,
        int                     *valuelenp,
        int                     flags)
{
        struct xfs_da_args      args;
        uint                    lock_mode;
        int                     error;

        ASSERT((flags & (ATTR_ALLOC | ATTR_KERNOVAL)) || *value);

        XFS_STATS_INC(ip->i_mount, xs_attr_get);

        if (XFS_FORCED_SHUTDOWN(ip->i_mount))
                return -EIO;

        error = xfs_attr_args_init(&args, ip, name, flags);
        if (error)
                return error;

        /* Entirely possible to look up a name which doesn't exist */
        args.op_flags = XFS_DA_OP_OKNOENT;
        if (flags & ATTR_ALLOC)
                args.op_flags |= XFS_DA_OP_ALLOCVAL;
        else
                args.value = *value;
        args.valuelen = *valuelenp;

        lock_mode = xfs_ilock_attr_map_shared(ip);
        error = xfs_attr_get_ilocked(ip, &args);
        xfs_iunlock(ip, lock_mode);
        *valuelenp = args.valuelen;

        /* on error, we have to clean up allocated value buffers */
        if (error) {
                if (flags & ATTR_ALLOC) {
                        kmem_free(args.value);
                        *value = NULL;
                }
                return error;
        }
        *value = args.value;
        return 0;
}

/*
 * Calculate how many blocks we need for the new attribute,
 */
STATIC int
xfs_attr_calc_size(
        struct xfs_da_args      *args,
        int                     *local)
{
        struct xfs_mount        *mp = args->dp->i_mount;
        int                     size;
        int                     nblks;

        /*
         * Determine space new attribute will use, and if it would be
         * "local" or "remote" (note: local != inline).
         */
        size = xfs_attr_leaf_newentsize(args, local);
        nblks = XFS_DAENTER_SPACE_RES(mp, XFS_ATTR_FORK);
        if (*local) {
                if (size > (args->geo->blksize / 2)) {
                        /* Double split possible */
                        nblks *= 2;
                }
        } else {
                /*
                 * Out of line attribute, cannot double split, but
                 * make room for the attribute value itself.
                 */
                uint    dblocks = xfs_attr3_rmt_blocks(mp, args->valuelen);
                nblks += dblocks;
                nblks += XFS_NEXTENTADD_SPACE_RES(mp, dblocks, XFS_ATTR_FORK);
        }

        return nblks;
}

STATIC int
xfs_attr_try_sf_addname(
        struct xfs_inode        *dp,
        struct xfs_da_args      *args)
{

        struct xfs_mount        *mp = dp->i_mount;
        int                     error, error2;

        error = xfs_attr_shortform_addname(args);
        if (error == -ENOSPC)
                return error;

        /*
         * Commit the shortform mods, and we're done.
         * NOTE: this is also the error path (EEXIST, etc).
         */
        if (!error && (args->flags & ATTR_KERNOTIME) == 0)
                xfs_trans_ichgtime(args->trans, dp, XFS_ICHGTIME_CHG);

        if (mp->m_flags & XFS_MOUNT_WSYNC)
                xfs_trans_set_sync(args->trans);

        error2 = xfs_trans_commit(args->trans);
        args->trans = NULL;
        return error ? error : error2;
}

/*
 * Set the attribute specified in @args.
 */
int
xfs_attr_set_args(
        struct xfs_da_args      *args)
{
        struct xfs_inode        *dp = args->dp;
        struct xfs_buf          *leaf_bp = NULL;
        int                     error;

        /*
         * If the attribute list is non-existent or a shortform list,
         * upgrade it to a single-leaf-block attribute list.
         */
        if (dp->i_d.di_aformat == XFS_DINODE_FMT_LOCAL ||
            (dp->i_d.di_aformat == XFS_DINODE_FMT_EXTENTS &&
             dp->i_d.di_anextents == 0)) {

                /*
                 * Build initial attribute list (if required).
                 */
                if (dp->i_d.di_aformat == XFS_DINODE_FMT_EXTENTS)
                        xfs_attr_shortform_create(args);

                /*
                 * Try to add the attr to the attribute list in the inode.
                 */
                error = xfs_attr_try_sf_addname(dp, args);
                if (error != -ENOSPC)
                        return error;

                /*
                 * It won't fit in the shortform, transform to a leaf block.
                 * GROT: another possible req'mt for a double-split btree op.
                 */
                error = xfs_attr_shortform_to_leaf(args, &leaf_bp);
                if (error)
                        return error;

                /*
                 * Prevent the leaf buffer from being unlocked so that a
                 * concurrent AIL push cannot grab the half-baked leaf
                 * buffer and run into problems with the write verifier.
                 * Once we're done rolling the transaction we can release
                 * the hold and add the attr to the leaf.
                 */
                xfs_trans_bhold(args->trans, leaf_bp);
                error = xfs_defer_finish(&args->trans);
                xfs_trans_bhold_release(args->trans, leaf_bp);
                if (error) {
                        xfs_trans_brelse(args->trans, leaf_bp);
                        return error;
                }
        }

        if (xfs_bmap_one_block(dp, XFS_ATTR_FORK))
                error = xfs_attr_leaf_addname(args);
        else
                error = xfs_attr_node_addname(args);
        return error;
}

/*
 * Remove the attribute specified in @args.
 */
int
xfs_attr_remove_args(
        struct xfs_da_args      *args)
{
        struct xfs_inode        *dp = args->dp;
        int                     error;

        if (!xfs_inode_hasattr(dp)) {
                error = -ENOATTR;
        } else if (dp->i_d.di_aformat == XFS_DINODE_FMT_LOCAL) {
                ASSERT(dp->i_afp->if_flags & XFS_IFINLINE);
                error = xfs_attr_shortform_remove(args);
        } else if (xfs_bmap_one_block(dp, XFS_ATTR_FORK)) {
                error = xfs_attr_leaf_removename(args);
        } else {
                error = xfs_attr_node_removename(args);
        }

        return error;
}

int
xfs_attr_set(
        struct xfs_inode        *dp,
        const unsigned char     *name,
        unsigned char           *value,
        int                     valuelen,
        int                     flags)
{
        struct xfs_mount        *mp = dp->i_mount;
        struct xfs_da_args      args;
        struct xfs_trans_res    tres;
        int                     rsvd = (flags & ATTR_ROOT) != 0;
        int                     error, local;

        XFS_STATS_INC(mp, xs_attr_set);

        if (XFS_FORCED_SHUTDOWN(dp->i_mount))
                return -EIO;

        error = xfs_attr_args_init(&args, dp, name, flags);
        if (error)
                return error;

        args.value = value;
        args.valuelen = valuelen;
        args.op_flags = XFS_DA_OP_ADDNAME | XFS_DA_OP_OKNOENT;
        args.total = xfs_attr_calc_size(&args, &local);

        error = xfs_qm_dqattach(dp);
        if (error)
                return error;

        /*
         * If the inode doesn't have an attribute fork, add one.
         * (inode must not be locked when we call this routine)
         */
        if (XFS_IFORK_Q(dp) == 0) {
                int sf_size = sizeof(xfs_attr_sf_hdr_t) +
                        XFS_ATTR_SF_ENTSIZE_BYNAME(args.namelen, valuelen);

                error = xfs_bmap_add_attrfork(dp, sf_size, rsvd);
                if (error)
                        return error;
        }

        tres.tr_logres = M_RES(mp)->tr_attrsetm.tr_logres +
                         M_RES(mp)->tr_attrsetrt.tr_logres * args.total;
        tres.tr_logcount = XFS_ATTRSET_LOG_COUNT;
        tres.tr_logflags = XFS_TRANS_PERM_LOG_RES;

        /*
         * Root fork attributes can use reserved data blocks for this
         * operation if necessary
         */
        error = xfs_trans_alloc(mp, &tres, args.total, 0,
                        rsvd ? XFS_TRANS_RESERVE : 0, &args.trans);
        if (error)
                return error;

        xfs_ilock(dp, XFS_ILOCK_EXCL);
        error = xfs_trans_reserve_quota_nblks(args.trans, dp, args.total, 0,
                                rsvd ? XFS_QMOPT_RES_REGBLKS | XFS_QMOPT_FORCE_RES :
                                       XFS_QMOPT_RES_REGBLKS);
        if (error)
                goto out_trans_cancel;

        xfs_trans_ijoin(args.trans, dp, 0);
        error = xfs_attr_set_args(&args);
        if (error)
                goto out_trans_cancel;
        if (!args.trans) {
                /* shortform attribute has already been committed */
                goto out_unlock;
        }

        /*
         * If this is a synchronous mount, make sure that the
         * transaction goes to disk before returning to the user.
         */
        if (mp->m_flags & XFS_MOUNT_WSYNC)
                xfs_trans_set_sync(args.trans);

        if ((flags & ATTR_KERNOTIME) == 0)
                xfs_trans_ichgtime(args.trans, dp, XFS_ICHGTIME_CHG);

        /*
         * Commit the last in the sequence of transactions.
         */
        xfs_trans_log_inode(args.trans, dp, XFS_ILOG_CORE);
        error = xfs_trans_commit(args.trans);
out_unlock:
        xfs_iunlock(dp, XFS_ILOCK_EXCL);
        return error;

out_trans_cancel:
        if (args.trans)
                xfs_trans_cancel(args.trans);
        goto out_unlock;
}

/*
 * Generic handler routine to remove a name from an attribute list.
 * Transitions attribute list from Btree to shortform as necessary.
 */
int
xfs_attr_remove(
        struct xfs_inode        *dp,
        const unsigned char     *name,
        int                     flags)
{
        struct xfs_mount        *mp = dp->i_mount;
        struct xfs_da_args      args;
        int                     error;

        XFS_STATS_INC(mp, xs_attr_remove);

        if (XFS_FORCED_SHUTDOWN(dp->i_mount))
                return -EIO;

        error = xfs_attr_args_init(&args, dp, name, flags);
        if (error)
                return error;

        /*
         * we have no control over the attribute names that userspace passes us
         * to remove, so we have to allow the name lookup prior to attribute
         * removal to fail.
         */
        args.op_flags = XFS_DA_OP_OKNOENT;

        error = xfs_qm_dqattach(dp);
        if (error)
                return error;

        /*
         * Root fork attributes can use reserved data blocks for this
         * operation if necessary
         */
        error = xfs_trans_alloc(mp, &M_RES(mp)->tr_attrrm,
                        XFS_ATTRRM_SPACE_RES(mp), 0,
                        (flags & ATTR_ROOT) ? XFS_TRANS_RESERVE : 0,
                        &args.trans);
        if (error)
                return error;

        xfs_ilock(dp, XFS_ILOCK_EXCL);
        /*
         * No need to make quota reservations here. We expect to release some
         * blocks not allocate in the common case.
         */
        xfs_trans_ijoin(args.trans, dp, 0);

        error = xfs_attr_remove_args(&args);
        if (error)
                goto out;

        /*
         * If this is a synchronous mount, make sure that the
         * transaction goes to disk before returning to the user.
         */
        if (mp->m_flags & XFS_MOUNT_WSYNC)
                xfs_trans_set_sync(args.trans);

        if ((flags & ATTR_KERNOTIME) == 0)
                xfs_trans_ichgtime(args.trans, dp, XFS_ICHGTIME_CHG);

        /*
         * Commit the last in the sequence of transactions.
         */
        xfs_trans_log_inode(args.trans, dp, XFS_ILOG_CORE);
        error = xfs_trans_commit(args.trans);
        xfs_iunlock(dp, XFS_ILOCK_EXCL);

        return error;

out:
        if (args.trans)
                xfs_trans_cancel(args.trans);
        xfs_iunlock(dp, XFS_ILOCK_EXCL);
        return error;
}

/*========================================================================
 * External routines when attribute list is inside the inode
 *========================================================================*/

/*
 * Add a name to the shortform attribute list structure
 * This is the external routine.
 */
STATIC int
xfs_attr_shortform_addname(xfs_da_args_t *args)
{
        int newsize, forkoff, retval;

        trace_xfs_attr_sf_addname(args);

        retval = xfs_attr_shortform_lookup(args);
        if ((args->flags & ATTR_REPLACE) && (retval == -ENOATTR)) {
                return retval;
        } else if (retval == -EEXIST) {
                if (args->flags & ATTR_CREATE)
                        return retval;
                retval = xfs_attr_shortform_remove(args);
                if (retval)
                        return retval;
                /*
                 * Since we have removed the old attr, clear ATTR_REPLACE so
                 * that the leaf format add routine won't trip over the attr
                 * not being around.
                 */
                args->flags &= ~ATTR_REPLACE;
        }

        if (args->namelen >= XFS_ATTR_SF_ENTSIZE_MAX ||
            args->valuelen >= XFS_ATTR_SF_ENTSIZE_MAX)
                return -ENOSPC;

        newsize = XFS_ATTR_SF_TOTSIZE(args->dp);
        newsize += XFS_ATTR_SF_ENTSIZE_BYNAME(args->namelen, args->valuelen);

        forkoff = xfs_attr_shortform_bytesfit(args->dp, newsize);
        if (!forkoff)
                return -ENOSPC;

        xfs_attr_shortform_add(args, forkoff);
        return 0;
}


/*========================================================================
 * External routines when attribute list is one block
 *========================================================================*/

/*
 * Add a name to the leaf attribute list structure
 *
 * This leaf block cannot have a "remote" value, we only call this routine
 * if bmap_one_block() says there is only one block (ie: no remote blks).
 */
STATIC int
xfs_attr_leaf_addname(
        struct xfs_da_args      *args)
{
        struct xfs_inode        *dp;
        struct xfs_buf          *bp;
        int                     retval, error, forkoff;

        trace_xfs_attr_leaf_addname(args);

        /*
         * Read the (only) block in the attribute list in.
         */
        dp = args->dp;
        args->blkno = 0;
        error = xfs_attr3_leaf_read(args->trans, args->dp, args->blkno, -1, &bp);
        if (error)
                return error;

        /*
         * Look up the given attribute in the leaf block.  Figure out if
         * the given flags produce an error or call for an atomic rename.
         */
        retval = xfs_attr3_leaf_lookup_int(bp, args);
        if ((args->flags & ATTR_REPLACE) && (retval == -ENOATTR)) {
                xfs_trans_brelse(args->trans, bp);
                return retval;
        } else if (retval == -EEXIST) {
                if (args->flags & ATTR_CREATE) {        /* pure create op */
                        xfs_trans_brelse(args->trans, bp);
                        return retval;
                }

                trace_xfs_attr_leaf_replace(args);

                /* save the attribute state for later removal*/
                args->op_flags |= XFS_DA_OP_RENAME;     /* an atomic rename */
                args->blkno2 = args->blkno;             /* set 2nd entry info*/
                args->index2 = args->index;
                args->rmtblkno2 = args->rmtblkno;
                args->rmtblkcnt2 = args->rmtblkcnt;
                args->rmtvaluelen2 = args->rmtvaluelen;

                /*
                 * clear the remote attr state now that it is saved so that the
                 * values reflect the state of the attribute we are about to
                 * add, not the attribute we just found and will remove later.
                 */
                args->rmtblkno = 0;
                args->rmtblkcnt = 0;
                args->rmtvaluelen = 0;
        }

        /*
         * Add the attribute to the leaf block, transitioning to a Btree
         * if required.
         */
        retval = xfs_attr3_leaf_add(bp, args);
        if (retval == -ENOSPC) {
                /*
                 * Promote the attribute list to the Btree format, then
                 * Commit that transaction so that the node_addname() call
                 * can manage its own transactions.
                 */
                error = xfs_attr3_leaf_to_node(args);
                if (error)
                        return error;
                error = xfs_defer_finish(&args->trans);
                if (error)
                        return error;

                /*
                 * Commit the current trans (including the inode) and start
                 * a new one.
                 */
                error = xfs_trans_roll_inode(&args->trans, dp);
                if (error)
                        return error;

                /*
                 * Fob the whole rest of the problem off on the Btree code.
                 */
                error = xfs_attr_node_addname(args);
                return error;
        }

        /*
         * Commit the transaction that added the attr name so that
         * later routines can manage their own transactions.
         */
        error = xfs_trans_roll_inode(&args->trans, dp);
        if (error)
                return error;

        /*
         * If there was an out-of-line value, allocate the blocks we
         * identified for its storage and copy the value.  This is done
         * after we create the attribute so that we don't overflow the
         * maximum size of a transaction and/or hit a deadlock.
         */
        if (args->rmtblkno > 0) {
                error = xfs_attr_rmtval_set(args);
                if (error)
                        return error;
        }

        /*
         * If this is an atomic rename operation, we must "flip" the
         * incomplete flags on the "new" and "old" attribute/value pairs
         * so that one disappears and one appears atomically.  Then we
         * must remove the "old" attribute/value pair.
         */
        if (args->op_flags & XFS_DA_OP_RENAME) {
                /*
                 * In a separate transaction, set the incomplete flag on the
                 * "old" attr and clear the incomplete flag on the "new" attr.
                 */
                error = xfs_attr3_leaf_flipflags(args);
                if (error)
                        return error;

                /*
                 * Dismantle the "old" attribute/value pair by removing
                 * a "remote" value (if it exists).
                 */
                args->index = args->index2;
                args->blkno = args->blkno2;
                args->rmtblkno = args->rmtblkno2;
                args->rmtblkcnt = args->rmtblkcnt2;
                args->rmtvaluelen = args->rmtvaluelen2;
                if (args->rmtblkno) {
                        error = xfs_attr_rmtval_remove(args);
                        if (error)
                                return error;
                }

                /*
                 * Read in the block containing the "old" attr, then
                 * remove the "old" attr from that block (neat, huh!)
                 */
                error = xfs_attr3_leaf_read(args->trans, args->dp, args->blkno,
                                           -1, &bp);
                if (error)
                        return error;

                xfs_attr3_leaf_remove(bp, args);

                /*
                 * If the result is small enough, shrink it all into the inode.
                 */
                if ((forkoff = xfs_attr_shortform_allfit(bp, dp))) {
                        error = xfs_attr3_leaf_to_shortform(bp, args, forkoff);
                        /* bp is gone due to xfs_da_shrink_inode */
                        if (error)
                                return error;
                        error = xfs_defer_finish(&args->trans);
                        if (error)
                                return error;
                }

                /*
                 * Commit the remove and start the next trans in series.
                 */
                error = xfs_trans_roll_inode(&args->trans, dp);

        } else if (args->rmtblkno > 0) {
                /*
                 * Added a "remote" value, just clear the incomplete flag.
                 */
                error = xfs_attr3_leaf_clearflag(args);
        }
        return error;
}

/*
 * Remove a name from the leaf attribute list structure
 *
 * This leaf block cannot have a "remote" value, we only call this routine
 * if bmap_one_block() says there is only one block (ie: no remote blks).
 */
STATIC int
xfs_attr_leaf_removename(
        struct xfs_da_args      *args)
{
        struct xfs_inode        *dp;
        struct xfs_buf          *bp;
        int                     error, forkoff;

        trace_xfs_attr_leaf_removename(args);

        /*
         * Remove the attribute.
         */
        dp = args->dp;
        args->blkno = 0;
        error = xfs_attr3_leaf_read(args->trans, args->dp, args->blkno, -1, &bp);
        if (error)
                return error;

        error = xfs_attr3_leaf_lookup_int(bp, args);
        if (error == -ENOATTR) {
                xfs_trans_brelse(args->trans, bp);
                return error;
        }

        xfs_attr3_leaf_remove(bp, args);

        /*
         * If the result is small enough, shrink it all into the inode.
         */
        if ((forkoff = xfs_attr_shortform_allfit(bp, dp))) {
                error = xfs_attr3_leaf_to_shortform(bp, args, forkoff);
                /* bp is gone due to xfs_da_shrink_inode */
                if (error)
                        return error;
                error = xfs_defer_finish(&args->trans);
                if (error)
                        return error;
        }
        return 0;
}

/*
 * Look up a name in a leaf attribute list structure.
 *
 * This leaf block cannot have a "remote" value, we only call this routine
 * if bmap_one_block() says there is only one block (ie: no remote blks).
 *
 * Returns 0 on successful retrieval, otherwise an error.
 */
STATIC int
xfs_attr_leaf_get(xfs_da_args_t *args)
{
        struct xfs_buf *bp;
        int error;

        trace_xfs_attr_leaf_get(args);

        args->blkno = 0;
        error = xfs_attr3_leaf_read(args->trans, args->dp, args->blkno, -1, &bp);
        if (error)
                return error;

        error = xfs_attr3_leaf_lookup_int(bp, args);
        if (error != -EEXIST)  {
                xfs_trans_brelse(args->trans, bp);
                return error;
        }
        error = xfs_attr3_leaf_getvalue(bp, args);
        xfs_trans_brelse(args->trans, bp);
        return error;
}

/*========================================================================
 * External routines when attribute list size > geo->blksize
 *========================================================================*/

/*
 * Add a name to a Btree-format attribute list.
 *
 * This will involve walking down the Btree, and may involve splitting
 * leaf nodes and even splitting intermediate nodes up to and including
 * the root node (a special case of an intermediate node).
 *
 * "Remote" attribute values confuse the issue and atomic rename operations
 * add a whole extra layer of confusion on top of that.
 */
STATIC int
xfs_attr_node_addname(
        struct xfs_da_args      *args)
{
        struct xfs_da_state     *state;
        struct xfs_da_state_blk *blk;
        struct xfs_inode        *dp;
        struct xfs_mount        *mp;
        int                     retval, error;

        trace_xfs_attr_node_addname(args);

        /*
         * Fill in bucket of arguments/results/context to carry around.
         */
        dp = args->dp;
        mp = dp->i_mount;
restart:
        state = xfs_da_state_alloc();
        state->args = args;
        state->mp = mp;

        /*
         * Search to see if name already exists, and get back a pointer
         * to where it should go.
         */
        error = xfs_da3_node_lookup_int(state, &retval);
        if (error)
                goto out;
        blk = &state->path.blk[ state->path.active-1 ];
        ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
        if ((args->flags & ATTR_REPLACE) && (retval == -ENOATTR)) {
                goto out;
        } else if (retval == -EEXIST) {
                if (args->flags & ATTR_CREATE)
                        goto out;

                trace_xfs_attr_node_replace(args);

                /* save the attribute state for later removal*/
                args->op_flags |= XFS_DA_OP_RENAME;     /* atomic rename op */
                args->blkno2 = args->blkno;             /* set 2nd entry info*/
                args->index2 = args->index;
                args->rmtblkno2 = args->rmtblkno;
                args->rmtblkcnt2 = args->rmtblkcnt;
                args->rmtvaluelen2 = args->rmtvaluelen;

                /*
                 * clear the remote attr state now that it is saved so that the
                 * values reflect the state of the attribute we are about to
                 * add, not the attribute we just found and will remove later.
                 */
                args->rmtblkno = 0;
                args->rmtblkcnt = 0;
                args->rmtvaluelen = 0;
        }

        retval = xfs_attr3_leaf_add(blk->bp, state->args);
        if (retval == -ENOSPC) {
                if (state->path.active == 1) {
                        /*
                         * Its really a single leaf node, but it had
                         * out-of-line values so it looked like it *might*
                         * have been a b-tree.
                         */
                        xfs_da_state_free(state);
                        state = NULL;
                        error = xfs_attr3_leaf_to_node(args);
                        if (error)
                                goto out;
                        error = xfs_defer_finish(&args->trans);
                        if (error)
                                goto out;

                        /*
                         * Commit the node conversion and start the next
                         * trans in the chain.
                         */
                        error = xfs_trans_roll_inode(&args->trans, dp);
                        if (error)
                                goto out;

                        goto restart;
                }

                /*
                 * Split as many Btree elements as required.
                 * This code tracks the new and old attr's location
                 * in the index/blkno/rmtblkno/rmtblkcnt fields and
                 * in the index2/blkno2/rmtblkno2/rmtblkcnt2 fields.
                 */
                error = xfs_da3_split(state);
                if (error)
                        goto out;
                error = xfs_defer_finish(&args->trans);
                if (error)
                        goto out;
        } else {
                /*
                 * Addition succeeded, update Btree hashvals.
                 */
                xfs_da3_fixhashpath(state, &state->path);
        }

        /*
         * Kill the state structure, we're done with it and need to
         * allow the buffers to come back later.
         */
        xfs_da_state_free(state);
        state = NULL;

        /*
         * Commit the leaf addition or btree split and start the next
         * trans in the chain.
         */
        error = xfs_trans_roll_inode(&args->trans, dp);
        if (error)
                goto out;

        /*
         * If there was an out-of-line value, allocate the blocks we
         * identified for its storage and copy the value.  This is done
         * after we create the attribute so that we don't overflow the
         * maximum size of a transaction and/or hit a deadlock.
         */
        if (args->rmtblkno > 0) {
                error = xfs_attr_rmtval_set(args);
                if (error)
                        return error;
        }

        /*
         * If this is an atomic rename operation, we must "flip" the
         * incomplete flags on the "new" and "old" attribute/value pairs
         * so that one disappears and one appears atomically.  Then we
         * must remove the "old" attribute/value pair.
         */
        if (args->op_flags & XFS_DA_OP_RENAME) {
                /*
                 * In a separate transaction, set the incomplete flag on the
                 * "old" attr and clear the incomplete flag on the "new" attr.
                 */
                error = xfs_attr3_leaf_flipflags(args);
                if (error)
                        goto out;

                /*
                 * Dismantle the "old" attribute/value pair by removing
                 * a "remote" value (if it exists).
                 */
                args->index = args->index2;
                args->blkno = args->blkno2;
                args->rmtblkno = args->rmtblkno2;
                args->rmtblkcnt = args->rmtblkcnt2;
                args->rmtvaluelen = args->rmtvaluelen2;
                if (args->rmtblkno) {
                        error = xfs_attr_rmtval_remove(args);
                        if (error)
                                return error;
                }

                /*
                 * Re-find the "old" attribute entry after any split ops.
                 * The INCOMPLETE flag means that we will find the "old"
                 * attr, not the "new" one.
                 */
                args->flags |= XFS_ATTR_INCOMPLETE;
                state = xfs_da_state_alloc();
                state->args = args;
                state->mp = mp;
                state->inleaf = 0;
                error = xfs_da3_node_lookup_int(state, &retval);
                if (error)
                        goto out;

                /*
                 * Remove the name and update the hashvals in the tree.
                 */
                blk = &state->path.blk[ state->path.active-1 ];
                ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
                error = xfs_attr3_leaf_remove(blk->bp, args);
                xfs_da3_fixhashpath(state, &state->path);

                /*
                 * Check to see if the tree needs to be collapsed.
                 */
                if (retval && (state->path.active > 1)) {
                        error = xfs_da3_join(state);
                        if (error)
                                goto out;
                        error = xfs_defer_finish(&args->trans);
                        if (error)
                                goto out;
                }

                /*
                 * Commit and start the next trans in the chain.
                 */
                error = xfs_trans_roll_inode(&args->trans, dp);
                if (error)
                        goto out;

        } else if (args->rmtblkno > 0) {
                /*
                 * Added a "remote" value, just clear the incomplete flag.
                 */
                error = xfs_attr3_leaf_clearflag(args);
                if (error)
                        goto out;
        }
        retval = error = 0;

out:
        if (state)
                xfs_da_state_free(state);
        if (error)
                return error;
        return retval;
}

/*
 * Remove a name from a B-tree attribute list.
 *
 * This will involve walking down the Btree, and may involve joining
 * leaf nodes and even joining intermediate nodes up to and including
 * the root node (a special case of an intermediate node).
 */
STATIC int
xfs_attr_node_removename(
        struct xfs_da_args      *args)
{
        struct xfs_da_state     *state;
        struct xfs_da_state_blk *blk;
        struct xfs_inode        *dp;
        struct xfs_buf          *bp;
        int                     retval, error, forkoff;

        trace_xfs_attr_node_removename(args);

        /*
         * Tie a string around our finger to remind us where we are.
         */
        dp = args->dp;
        state = xfs_da_state_alloc();
        state->args = args;
        state->mp = dp->i_mount;

        /*
         * Search to see if name exists, and get back a pointer to it.
         */
        error = xfs_da3_node_lookup_int(state, &retval);
        if (error || (retval != -EEXIST)) {
                if (error == 0)
                        error = retval;
                goto out;
        }

        /*
         * If there is an out-of-line value, de-allocate the blocks.
         * This is done before we remove the attribute so that we don't
         * overflow the maximum size of a transaction and/or hit a deadlock.
         */
        blk = &state->path.blk[ state->path.active-1 ];
        ASSERT(blk->bp != NULL);
        ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
        if (args->rmtblkno > 0) {
                /*
                 * Fill in disk block numbers in the state structure
                 * so that we can get the buffers back after we commit
                 * several transactions in the following calls.
                 */
                error = xfs_attr_fillstate(state);
                if (error)
                        goto out;

                /*
                 * Mark the attribute as INCOMPLETE, then bunmapi() the
                 * remote value.
                 */
                error = xfs_attr3_leaf_setflag(args);
                if (error)
                        goto out;
                error = xfs_attr_rmtval_remove(args);
                if (error)
                        goto out;

                /*
                 * Refill the state structure with buffers, the prior calls
                 * released our buffers.
                 */
                error = xfs_attr_refillstate(state);
                if (error)
                        goto out;
        }

        /*
         * Remove the name and update the hashvals in the tree.
         */
        blk = &state->path.blk[ state->path.active-1 ];
        ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
        retval = xfs_attr3_leaf_remove(blk->bp, args);
        xfs_da3_fixhashpath(state, &state->path);

        /*
         * Check to see if the tree needs to be collapsed.
         */
        if (retval && (state->path.active > 1)) {
                error = xfs_da3_join(state);
                if (error)
                        goto out;
                error = xfs_defer_finish(&args->trans);
                if (error)
                        goto out;
                /*
                 * Commit the Btree join operation and start a new trans.
                 */
                error = xfs_trans_roll_inode(&args->trans, dp);
                if (error)
                        goto out;
        }

        /*
         * If the result is small enough, push it all into the inode.
         */
        if (xfs_bmap_one_block(dp, XFS_ATTR_FORK)) {
                /*
                 * Have to get rid of the copy of this dabuf in the state.
                 */
                ASSERT(state->path.active == 1);
                ASSERT(state->path.blk[0].bp);
                state->path.blk[0].bp = NULL;

                error = xfs_attr3_leaf_read(args->trans, args->dp, 0, -1, &bp);
                if (error)
                        goto out;

                if ((forkoff = xfs_attr_shortform_allfit(bp, dp))) {
                        error = xfs_attr3_leaf_to_shortform(bp, args, forkoff);
                        /* bp is gone due to xfs_da_shrink_inode */
                        if (error)
                                goto out;
                        error = xfs_defer_finish(&args->trans);
                        if (error)
                                goto out;
                } else
                        xfs_trans_brelse(args->trans, bp);
        }
        error = 0;

out:
        xfs_da_state_free(state);
        return error;
}

/*
 * Fill in the disk block numbers in the state structure for the buffers
 * that are attached to the state structure.
 * This is done so that we can quickly reattach ourselves to those buffers
 * after some set of transaction commits have released these buffers.
 */
STATIC int
xfs_attr_fillstate(xfs_da_state_t *state)
{
        xfs_da_state_path_t *path;
        xfs_da_state_blk_t *blk;
        int level;

        trace_xfs_attr_fillstate(state->args);

        /*
         * Roll down the "path" in the state structure, storing the on-disk
         * block number for those buffers in the "path".
         */
        path = &state->path;
        ASSERT((path->active >= 0) && (path->active < XFS_DA_NODE_MAXDEPTH));
        for (blk = path->blk, level = 0; level < path->active; blk++, level++) {
                if (blk->bp) {
                        blk->disk_blkno = XFS_BUF_ADDR(blk->bp);
                        blk->bp = NULL;
                } else {
                        blk->disk_blkno = 0;
                }
        }

        /*
         * Roll down the "altpath" in the state structure, storing the on-disk
         * block number for those buffers in the "altpath".
         */
        path = &state->altpath;
        ASSERT((path->active >= 0) && (path->active < XFS_DA_NODE_MAXDEPTH));
        for (blk = path->blk, level = 0; level < path->active; blk++, level++) {
                if (blk->bp) {
                        blk->disk_blkno = XFS_BUF_ADDR(blk->bp);
                        blk->bp = NULL;
                } else {
                        blk->disk_blkno = 0;
                }
        }

        return 0;
}

/*
 * Reattach the buffers to the state structure based on the disk block
 * numbers stored in the state structure.
 * This is done after some set of transaction commits have released those
 * buffers from our grip.
 */
STATIC int
xfs_attr_refillstate(xfs_da_state_t *state)
{
        xfs_da_state_path_t *path;
        xfs_da_state_blk_t *blk;
        int level, error;

        trace_xfs_attr_refillstate(state->args);

        /*
         * Roll down the "path" in the state structure, storing the on-disk
         * block number for those buffers in the "path".
         */
        path = &state->path;
        ASSERT((path->active >= 0) && (path->active < XFS_DA_NODE_MAXDEPTH));
        for (blk = path->blk, level = 0; level < path->active; blk++, level++) {
                if (blk->disk_blkno) {
                        error = xfs_da3_node_read(state->args->trans,
                                                state->args->dp,
                                                blk->blkno, blk->disk_blkno,
                                                &blk->bp, XFS_ATTR_FORK);
                        if (error)
                                return error;
                } else {
                        blk->bp = NULL;
                }
        }

        /*
         * Roll down the "altpath" in the state structure, storing the on-disk
         * block number for those buffers in the "altpath".
         */
        path = &state->altpath;
        ASSERT((path->active >= 0) && (path->active < XFS_DA_NODE_MAXDEPTH));
        for (blk = path->blk, level = 0; level < path->active; blk++, level++) {
                if (blk->disk_blkno) {
                        error = xfs_da3_node_read(state->args->trans,
                                                state->args->dp,
                                                blk->blkno, blk->disk_blkno,
                                                &blk->bp, XFS_ATTR_FORK);
                        if (error)
                                return error;
                } else {
                        blk->bp = NULL;
                }
        }

        return 0;
}

/*
 * Retrieve the attribute data from a node attribute list.
 *
 * This routine gets called for any attribute fork that has more than one
 * block, ie: both true Btree attr lists and for single-leaf-blocks with
 * "remote" values taking up more blocks.
 *
 * Returns 0 on successful retrieval, otherwise an error.
 */
STATIC int
xfs_attr_node_get(xfs_da_args_t *args)
{
        xfs_da_state_t *state;
        xfs_da_state_blk_t *blk;
        int error, retval;
        int i;

        trace_xfs_attr_node_get(args);

        state = xfs_da_state_alloc();
        state->args = args;
        state->mp = args->dp->i_mount;

        /*
         * Search to see if name exists, and get back a pointer to it.
         */
        error = xfs_da3_node_lookup_int(state, &retval);
        if (error) {
                retval = error;
                goto out_release;
        }
        if (retval != -EEXIST)
                goto out_release;

        /*
         * Get the value, local or "remote"
         */
        blk = &state->path.blk[state->path.active - 1];
        retval = xfs_attr3_leaf_getvalue(blk->bp, args);

        /*
         * If not in a transaction, we have to release all the buffers.
         */
out_release:
        for (i = 0; i < state->path.active; i++) {
                xfs_trans_brelse(args->trans, state->path.blk[i].bp);
                state->path.blk[i].bp = NULL;
        }

        xfs_da_state_free(state);
        return retval;
}

/* Returns true if the attribute entry name is valid. */
bool
xfs_attr_namecheck(
        const void      *name,
        size_t          length)
{
        /*
         * MAXNAMELEN includes the trailing null, but (name/length) leave it
         * out, so use >= for the length check.
         */
        if (length >= MAXNAMELEN)
                return false;

        /* There shouldn't be any nulls here */
        return !memchr(name, 0, length);
}