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

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_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_quota.h"
#include "xfs_trans_space.h"
#include "xfs_trace.h"
#include "xfs_attr_item.h"
#include "xfs_xattr.h"

struct kmem_cache               *xfs_attr_intent_cache;

/*
 * 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_removename(xfs_da_args_t *args);
STATIC int xfs_attr_leaf_hasname(struct xfs_da_args *args, struct xfs_buf **bp);
STATIC int xfs_attr_leaf_try_add(struct xfs_da_args *args);

/*
 * Internal routines when attribute list is more than one block.
 */
STATIC int xfs_attr_node_get(xfs_da_args_t *args);
STATIC void xfs_attr_restore_rmt_blk(struct xfs_da_args *args);
static int xfs_attr_node_try_addname(struct xfs_attr_intent *attr);
STATIC int xfs_attr_node_addname_find_attr(struct xfs_attr_intent *attr);
STATIC int xfs_attr_node_remove_attr(struct xfs_attr_intent *attr);
STATIC int xfs_attr_node_lookup(struct xfs_da_args *args,
                struct xfs_da_state *state);

int
xfs_inode_hasattr(
        struct xfs_inode        *ip)
{
        if (!xfs_inode_has_attr_fork(ip))
                return 0;
        if (ip->i_af.if_format == XFS_DINODE_FMT_EXTENTS &&
            ip->i_af.if_nextents == 0)
                return 0;
        return 1;
}

/*
 * Returns true if the there is exactly only block in the attr fork, in which
 * case the attribute fork consists of a single leaf block entry.
 */
bool
xfs_attr_is_leaf(
        struct xfs_inode        *ip)
{
        struct xfs_ifork        *ifp = &ip->i_af;
        struct xfs_iext_cursor  icur;
        struct xfs_bmbt_irec    imap;

        if (ifp->if_nextents != 1 || ifp->if_format != XFS_DINODE_FMT_EXTENTS)
                return false;

        xfs_iext_first(ifp, &icur);
        xfs_iext_get_extent(ifp, &icur, &imap);
        return imap.br_startoff == 0 && imap.br_blockcount == 1;
}

/*
 * XXX (dchinner): name path state saving and refilling is an optimisation to
 * avoid needing to look up name entries after rolling transactions removing
 * remote xattr blocks between the name entry lookup and name entry removal.
 * This optimisation got sidelined when combining the set and remove state
 * machines, but the code has been left in place because it is worthwhile to
 * restore the optimisation once the combined state machine paths have settled.
 *
 * This comment is a public service announcement to remind Future Dave that he
 * still needs to restore this code to working order.
 */
#if 0
/*
 * 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_daddr(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_daddr(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_mapped(state->args->trans,
                                        state->args->dp, 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_mapped(state->args->trans,
                                        state->args->dp, blk->disk_blkno,
                                        &blk->bp, XFS_ATTR_FORK);
                        if (error)
                                return error;
                } else {
                        blk->bp = NULL;
                }
        }

        return 0;
}
#else
static int xfs_attr_fillstate(xfs_da_state_t *state) { return 0; }
#endif

/*========================================================================
 * 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_da_args      *args)
{
        ASSERT(xfs_isilocked(args->dp, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));

        if (!xfs_inode_hasattr(args->dp))
                return -ENOATTR;

        if (args->dp->i_af.if_format == XFS_DINODE_FMT_LOCAL)
                return xfs_attr_shortform_getvalue(args);
        if (xfs_attr_is_leaf(args->dp))
                return xfs_attr_leaf_get(args);
        return xfs_attr_node_get(args);
}

/*
 * Retrieve an extended attribute by name, and its value if requested.
 *
 * If args->valuelen is zero, 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 args.valuelen.
 *
 * If args->value is NULL but args->valuelen is non-zero, allocate the buffer
 * for the value after existence of the attribute has been determined. The
 * caller always has to free args->value if it is set, no matter if this
 * function was successful or not.
 *
 * If the attribute is found, but exceeds the size limit set by the caller in
 * args->valuelen, return -ERANGE with the size of the attribute that was found
 * in args->valuelen.
 */
int
xfs_attr_get(
        struct xfs_da_args      *args)
{
        uint                    lock_mode;
        int                     error;

        XFS_STATS_INC(args->dp->i_mount, xs_attr_get);

        if (xfs_is_shutdown(args->dp->i_mount))
                return -EIO;

        args->geo = args->dp->i_mount->m_attr_geo;
        args->whichfork = XFS_ATTR_FORK;
        args->hashval = xfs_da_hashname(args->name, args->namelen);

        /* Entirely possible to look up a name which doesn't exist */
        args->op_flags = XFS_DA_OP_OKNOENT;

        lock_mode = xfs_ilock_attr_map_shared(args->dp);
        error = xfs_attr_get_ilocked(args);
        xfs_iunlock(args->dp, lock_mode);

        return error;
}

/*
 * Calculate how many blocks we need for the new attribute,
 */
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;
}

/* Initialize transaction reservation for attr operations */
void
xfs_init_attr_trans(
        struct xfs_da_args      *args,
        struct xfs_trans_res    *tres,
        unsigned int            *total)
{
        struct xfs_mount        *mp = args->dp->i_mount;

        if (args->value) {
                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;
                *total = args->total;
        } else {
                *tres = M_RES(mp)->tr_attrrm;
                *total = XFS_ATTRRM_SPACE_RES(mp);
        }
}

/*
 * Add an attr to a shortform fork. If there is no space,
 * xfs_attr_shortform_addname() will convert to leaf format and return -ENOSPC.
 * to use.
 */
STATIC int
xfs_attr_try_sf_addname(
        struct xfs_inode        *dp,
        struct xfs_da_args      *args)
{

        int                     error;

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

        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->op_flags & XFS_DA_OP_NOTIME))
                xfs_trans_ichgtime(args->trans, dp, XFS_ICHGTIME_CHG);

        if (xfs_has_wsync(dp->i_mount))
                xfs_trans_set_sync(args->trans);

        return error;
}

static int
xfs_attr_sf_addname(
        struct xfs_attr_intent          *attr)
{
        struct xfs_da_args              *args = attr->xattri_da_args;
        struct xfs_inode                *dp = args->dp;
        int                             error = 0;

        error = xfs_attr_try_sf_addname(dp, args);
        if (error != -ENOSPC) {
                ASSERT(!error || error == -EEXIST);
                attr->xattri_dela_state = XFS_DAS_DONE;
                goto out;
        }

        /*
         * 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);
        if (error)
                return error;

        attr->xattri_dela_state = XFS_DAS_LEAF_ADD;
out:
        trace_xfs_attr_sf_addname_return(attr->xattri_dela_state, args->dp);
        return error;
}

/*
 * Handle the state change on completion of a multi-state attr operation.
 *
 * If the XFS_DA_OP_REPLACE flag is set, this means the operation was the first
 * modification in a attr replace operation and we still have to do the second
 * state, indicated by @replace_state.
 *
 * We consume the XFS_DA_OP_REPLACE flag so that when we are called again on
 * completion of the second half of the attr replace operation we correctly
 * signal that it is done.
 */
static enum xfs_delattr_state
xfs_attr_complete_op(
        struct xfs_attr_intent  *attr,
        enum xfs_delattr_state  replace_state)
{
        struct xfs_da_args      *args = attr->xattri_da_args;
        bool                    do_replace = args->op_flags & XFS_DA_OP_REPLACE;

        args->op_flags &= ~XFS_DA_OP_REPLACE;
        args->attr_filter &= ~XFS_ATTR_INCOMPLETE;
        if (do_replace)
                return replace_state;

        return XFS_DAS_DONE;
}

static int
xfs_attr_leaf_addname(
        struct xfs_attr_intent  *attr)
{
        struct xfs_da_args      *args = attr->xattri_da_args;
        int                     error;

        ASSERT(xfs_attr_is_leaf(args->dp));

        /*
         * Use the leaf buffer we may already hold locked as a result of
         * a sf-to-leaf conversion.
         */
        error = xfs_attr_leaf_try_add(args);

        if (error == -ENOSPC) {
                error = xfs_attr3_leaf_to_node(args);
                if (error)
                        return error;

                /*
                 * We're not in leaf format anymore, so roll the transaction and
                 * retry the add to the newly allocated node block.
                 */
                attr->xattri_dela_state = XFS_DAS_NODE_ADD;
                goto out;
        }
        if (error)
                return error;

        /*
         * We need to commit and roll if we need to allocate remote xattr blocks
         * or perform more xattr manipulations. Otherwise there is nothing more
         * to do and we can return success.
         */
        if (args->rmtblkno)
                attr->xattri_dela_state = XFS_DAS_LEAF_SET_RMT;
        else
                attr->xattri_dela_state = xfs_attr_complete_op(attr,
                                                        XFS_DAS_LEAF_REPLACE);
out:
        trace_xfs_attr_leaf_addname_return(attr->xattri_dela_state, args->dp);
        return error;
}

/*
 * Add an entry to a node format attr tree.
 *
 * Note that we might still have a leaf here - xfs_attr_is_leaf() cannot tell
 * the difference between leaf + remote attr blocks and a node format tree,
 * so we may still end up having to convert from leaf to node format here.
 */
static int
xfs_attr_node_addname(
        struct xfs_attr_intent  *attr)
{
        struct xfs_da_args      *args = attr->xattri_da_args;
        int                     error;

        error = xfs_attr_node_addname_find_attr(attr);
        if (error)
                return error;

        error = xfs_attr_node_try_addname(attr);
        if (error == -ENOSPC) {
                error = xfs_attr3_leaf_to_node(args);
                if (error)
                        return error;
                /*
                 * No state change, we really are in node form now
                 * but we need the transaction rolled to continue.
                 */
                goto out;
        }
        if (error)
                return error;

        if (args->rmtblkno)
                attr->xattri_dela_state = XFS_DAS_NODE_SET_RMT;
        else
                attr->xattri_dela_state = xfs_attr_complete_op(attr,
                                                        XFS_DAS_NODE_REPLACE);
out:
        trace_xfs_attr_node_addname_return(attr->xattri_dela_state, args->dp);
        return error;
}

static int
xfs_attr_rmtval_alloc(
        struct xfs_attr_intent          *attr)
{
        struct xfs_da_args              *args = attr->xattri_da_args;
        int                             error = 0;

        /*
         * 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 (attr->xattri_blkcnt > 0) {
                error = xfs_attr_rmtval_set_blk(attr);
                if (error)
                        return error;
                /* Roll the transaction only if there is more to allocate. */
                if (attr->xattri_blkcnt > 0)
                        goto out;
        }

        error = xfs_attr_rmtval_set_value(args);
        if (error)
                return error;

        attr->xattri_dela_state = xfs_attr_complete_op(attr,
                                                ++attr->xattri_dela_state);
        /*
         * If we are not doing a rename, we've finished the operation but still
         * have to clear the incomplete flag protecting the new attr from
         * exposing partially initialised state if we crash during creation.
         */
        if (attr->xattri_dela_state == XFS_DAS_DONE)
                error = xfs_attr3_leaf_clearflag(args);
out:
        trace_xfs_attr_rmtval_alloc(attr->xattri_dela_state, args->dp);
        return error;
}

/*
 * Mark an attribute entry INCOMPLETE and save pointers to the relevant buffers
 * for later deletion of the entry.
 */
static int
xfs_attr_leaf_mark_incomplete(
        struct xfs_da_args      *args,
        struct xfs_da_state     *state)
{
        int                     error;

        /*
         * 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)
                return error;

        /*
         * Mark the attribute as INCOMPLETE
         */
        return xfs_attr3_leaf_setflag(args);
}

/* Ensure the da state of an xattr deferred work item is ready to go. */
static inline void
xfs_attr_item_init_da_state(
        struct xfs_attr_intent  *attr)
{
        struct xfs_da_args      *args = attr->xattri_da_args;

        if (!attr->xattri_da_state)
                attr->xattri_da_state = xfs_da_state_alloc(args);
        else
                xfs_da_state_reset(attr->xattri_da_state, args);
}

/*
 * Initial setup for xfs_attr_node_removename.  Make sure the attr is there and
 * the blocks are valid.  Attr keys with remote blocks will be marked
 * incomplete.
 */
static
int xfs_attr_node_removename_setup(
        struct xfs_attr_intent          *attr)
{
        struct xfs_da_args              *args = attr->xattri_da_args;
        struct xfs_da_state             *state;
        int                             error;

        xfs_attr_item_init_da_state(attr);
        error = xfs_attr_node_lookup(args, attr->xattri_da_state);
        if (error != -EEXIST)
                goto out;
        error = 0;

        state = attr->xattri_da_state;
        ASSERT(state->path.blk[state->path.active - 1].bp != NULL);
        ASSERT(state->path.blk[state->path.active - 1].magic ==
                XFS_ATTR_LEAF_MAGIC);

        error = xfs_attr_leaf_mark_incomplete(args, state);
        if (error)
                goto out;
        if (args->rmtblkno > 0)
                error = xfs_attr_rmtval_invalidate(args);
out:
        if (error) {
                xfs_da_state_free(attr->xattri_da_state);
                attr->xattri_da_state = NULL;
        }

        return error;
}

/*
 * Remove the original attr we have just replaced. This is dependent on the
 * original lookup and insert placing the old attr in args->blkno/args->index
 * and the new attr in args->blkno2/args->index2.
 */
static int
xfs_attr_leaf_remove_attr(
        struct xfs_attr_intent          *attr)
{
        struct xfs_da_args              *args = attr->xattri_da_args;
        struct xfs_inode                *dp = args->dp;
        struct xfs_buf                  *bp = NULL;
        int                             forkoff;
        int                             error;

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

        xfs_attr3_leaf_remove(bp, args);

        forkoff = xfs_attr_shortform_allfit(bp, dp);
        if (forkoff)
                error = xfs_attr3_leaf_to_shortform(bp, args, forkoff);
                /* bp is gone due to xfs_da_shrink_inode */

        return error;
}

/*
 * Shrink an attribute from leaf to shortform. Used by the node format remove
 * path when the node format collapses to a single block and so we have to check
 * if it can be collapsed further.
 */
static int
xfs_attr_leaf_shrink(
        struct xfs_da_args      *args)
{
        struct xfs_inode        *dp = args->dp;
        struct xfs_buf          *bp;
        int                     forkoff;
        int                     error;

        if (!xfs_attr_is_leaf(dp))
                return 0;

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

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

        return error;
}

/*
 * Run the attribute operation specified in @attr.
 *
 * This routine is meant to function as a delayed operation and will set the
 * state to XFS_DAS_DONE when the operation is complete.  Calling functions will
 * need to handle this, and recall the function until either an error or
 * XFS_DAS_DONE is detected.
 */
int
xfs_attr_set_iter(
        struct xfs_attr_intent          *attr)
{
        struct xfs_da_args              *args = attr->xattri_da_args;
        int                             error = 0;

        /* State machine switch */
next_state:
        switch (attr->xattri_dela_state) {
        case XFS_DAS_UNINIT:
                ASSERT(0);
                return -EFSCORRUPTED;
        case XFS_DAS_SF_ADD:
                return xfs_attr_sf_addname(attr);
        case XFS_DAS_LEAF_ADD:
                return xfs_attr_leaf_addname(attr);
        case XFS_DAS_NODE_ADD:
                return xfs_attr_node_addname(attr);

        case XFS_DAS_SF_REMOVE:
                error = xfs_attr_sf_removename(args);
                attr->xattri_dela_state = xfs_attr_complete_op(attr,
                                                xfs_attr_init_add_state(args));
                break;
        case XFS_DAS_LEAF_REMOVE:
                error = xfs_attr_leaf_removename(args);
                attr->xattri_dela_state = xfs_attr_complete_op(attr,
                                                xfs_attr_init_add_state(args));
                break;
        case XFS_DAS_NODE_REMOVE:
                error = xfs_attr_node_removename_setup(attr);
                if (error == -ENOATTR &&
                    (args->op_flags & XFS_DA_OP_RECOVERY)) {
                        attr->xattri_dela_state = xfs_attr_complete_op(attr,
                                                xfs_attr_init_add_state(args));
                        error = 0;
                        break;
                }
                if (error)
                        return error;
                attr->xattri_dela_state = XFS_DAS_NODE_REMOVE_RMT;
                if (args->rmtblkno == 0)
                        attr->xattri_dela_state++;
                break;

        case XFS_DAS_LEAF_SET_RMT:
        case XFS_DAS_NODE_SET_RMT:
                error = xfs_attr_rmtval_find_space(attr);
                if (error)
                        return error;
                attr->xattri_dela_state++;
                fallthrough;

        case XFS_DAS_LEAF_ALLOC_RMT:
        case XFS_DAS_NODE_ALLOC_RMT:
                error = xfs_attr_rmtval_alloc(attr);
                if (error)
                        return error;
                if (attr->xattri_dela_state == XFS_DAS_DONE)
                        break;
                goto next_state;

        case XFS_DAS_LEAF_REPLACE:
        case XFS_DAS_NODE_REPLACE:
                /*
                 * We must "flip" the incomplete flags on the "new" and "old"
                 * attribute/value pairs so that one disappears and one appears
                 * atomically.
                 */
                error = xfs_attr3_leaf_flipflags(args);
                if (error)
                        return error;
                /*
                 * We must commit the flag value change now to make it atomic
                 * and then we can start the next trans in series at REMOVE_OLD.
                 */
                attr->xattri_dela_state++;
                break;

        case XFS_DAS_LEAF_REMOVE_OLD:
        case XFS_DAS_NODE_REMOVE_OLD:
                /*
                 * If we have a remote attr, start the process of removing it
                 * by invalidating any cached buffers.
                 *
                 * If we don't have a remote attr, we skip the remote block
                 * removal state altogether with a second state increment.
                 */
                xfs_attr_restore_rmt_blk(args);
                if (args->rmtblkno) {
                        error = xfs_attr_rmtval_invalidate(args);
                        if (error)
                                return error;
                } else {
                        attr->xattri_dela_state++;
                }

                attr->xattri_dela_state++;
                goto next_state;

        case XFS_DAS_LEAF_REMOVE_RMT:
        case XFS_DAS_NODE_REMOVE_RMT:
                error = xfs_attr_rmtval_remove(attr);
                if (error == -EAGAIN) {
                        error = 0;
                        break;
                }
                if (error)
                        return error;

                /*
                 * We've finished removing the remote attr blocks, so commit the
                 * transaction and move on to removing the attr name from the
                 * leaf/node block. Removing the attr might require a full
                 * transaction reservation for btree block freeing, so we
                 * can't do that in the same transaction where we removed the
                 * remote attr blocks.
                 */
                attr->xattri_dela_state++;
                break;

        case XFS_DAS_LEAF_REMOVE_ATTR:
                error = xfs_attr_leaf_remove_attr(attr);
                attr->xattri_dela_state = xfs_attr_complete_op(attr,
                                                xfs_attr_init_add_state(args));
                break;

        case XFS_DAS_NODE_REMOVE_ATTR:
                error = xfs_attr_node_remove_attr(attr);
                if (!error)
                        error = xfs_attr_leaf_shrink(args);
                attr->xattri_dela_state = xfs_attr_complete_op(attr,
                                                xfs_attr_init_add_state(args));
                break;
        default:
                ASSERT(0);
                break;
        }

        trace_xfs_attr_set_iter_return(attr->xattri_dela_state, args->dp);
        return error;
}


/*
 * Return EEXIST if attr is found, or ENOATTR if not
 */
static int
xfs_attr_lookup(
        struct xfs_da_args      *args)
{
        struct xfs_inode        *dp = args->dp;
        struct xfs_buf          *bp = NULL;
        struct xfs_da_state     *state;
        int                     error;

        if (!xfs_inode_hasattr(dp))
                return -ENOATTR;

        if (dp->i_af.if_format == XFS_DINODE_FMT_LOCAL) {
                if (xfs_attr_sf_findname(args))
                        return -EEXIST;
                return -ENOATTR;
        }

        if (xfs_attr_is_leaf(dp)) {
                error = xfs_attr_leaf_hasname(args, &bp);

                if (bp)
                        xfs_trans_brelse(args->trans, bp);

                return error;
        }

        state = xfs_da_state_alloc(args);
        error = xfs_attr_node_lookup(args, state);
        xfs_da_state_free(state);
        return error;
}

static void
xfs_attr_defer_add(
        struct xfs_da_args      *args,
        unsigned int            op_flags)
{

        struct xfs_attr_intent  *new;

        new = kmem_cache_zalloc(xfs_attr_intent_cache,
                        GFP_KERNEL | __GFP_NOFAIL);
        new->xattri_op_flags = op_flags;
        new->xattri_da_args = args;

        switch (op_flags) {
        case XFS_ATTRI_OP_FLAGS_SET:
                new->xattri_dela_state = xfs_attr_init_add_state(args);
                break;
        case XFS_ATTRI_OP_FLAGS_REPLACE:
                new->xattri_dela_state = xfs_attr_init_replace_state(args);
                break;
        case XFS_ATTRI_OP_FLAGS_REMOVE:
                new->xattri_dela_state = xfs_attr_init_remove_state(args);
                break;
        default:
                ASSERT(0);
        }

        xfs_defer_add(args->trans, &new->xattri_list, &xfs_attr_defer_type);
        trace_xfs_attr_defer_add(new->xattri_dela_state, args->dp);
}

/*
 * Note: If args->value is NULL the attribute will be removed, just like the
 * Linux ->setattr API.
 */
int
xfs_attr_set(
        struct xfs_da_args      *args)
{
        struct xfs_inode        *dp = args->dp;
        struct xfs_mount        *mp = dp->i_mount;
        struct xfs_trans_res    tres;
        bool                    rsvd = (args->attr_filter & XFS_ATTR_ROOT);
        int                     error, local;
        int                     rmt_blks = 0;
        unsigned int            total;

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

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

        args->geo = mp->m_attr_geo;
        args->whichfork = XFS_ATTR_FORK;
        args->hashval = xfs_da_hashname(args->name, args->namelen);

        /*
         * 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 as well.  Preserve the logged flag, since we need
         * to pass that through to the logging code.
         */
        args->op_flags = XFS_DA_OP_OKNOENT |
                                        (args->op_flags & XFS_DA_OP_LOGGED);

        if (args->value) {
                XFS_STATS_INC(mp, xs_attr_set);
                args->total = xfs_attr_calc_size(args, &local);

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

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

                if (!local)
                        rmt_blks = xfs_attr3_rmt_blocks(mp, args->valuelen);
        } else {
                XFS_STATS_INC(mp, xs_attr_remove);
                rmt_blks = xfs_attr3_rmt_blocks(mp, XFS_XATTR_SIZE_MAX);
        }

        /*
         * Root fork attributes can use reserved data blocks for this
         * operation if necessary
         */
        xfs_init_attr_trans(args, &tres, &total);
        error = xfs_trans_alloc_inode(dp, &tres, total, 0, rsvd, &args->trans);
        if (error)
                return error;

        if (args->value || xfs_inode_hasattr(dp)) {
                error = xfs_iext_count_may_overflow(dp, XFS_ATTR_FORK,
                                XFS_IEXT_ATTR_MANIP_CNT(rmt_blks));
                if (error == -EFBIG)
                        error = xfs_iext_count_upgrade(args->trans, dp,
                                        XFS_IEXT_ATTR_MANIP_CNT(rmt_blks));
                if (error)
                        goto out_trans_cancel;
        }

        error = xfs_attr_lookup(args);
        switch (error) {
        case -EEXIST:
                if (!args->value) {
                        /* if no value, we are performing a remove operation */
                        xfs_attr_defer_add(args, XFS_ATTRI_OP_FLAGS_REMOVE);
                        break;
                }

                /* Pure create fails if the attr already exists */
                if (args->attr_flags & XATTR_CREATE)
                        goto out_trans_cancel;
                xfs_attr_defer_add(args, XFS_ATTRI_OP_FLAGS_REPLACE);
                break;
        case -ENOATTR:
                /* Can't remove what isn't there. */
                if (!args->value)
                        goto out_trans_cancel;

                /* Pure replace fails if no existing attr to replace. */
                if (args->attr_flags & XATTR_REPLACE)
                        goto out_trans_cancel;
                xfs_attr_defer_add(args, XFS_ATTRI_OP_FLAGS_SET);
                break;
        default:
                goto out_trans_cancel;
        }

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

        if (!(args->op_flags & XFS_DA_OP_NOTIME))
                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;
}

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

static inline int xfs_attr_sf_totsize(struct xfs_inode *dp)
{
        struct xfs_attr_sf_hdr *sf = dp->i_af.if_data;

        return be16_to_cpu(sf->totsize);
}

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

        trace_xfs_attr_sf_addname(args);

        if (xfs_attr_sf_findname(args)) {
                int             error;

                ASSERT(args->op_flags & XFS_DA_OP_REPLACE);

                error = xfs_attr_sf_removename(args);
                if (error)
                        return error;

                /*
                 * Since we have removed the old attr, clear XFS_DA_OP_REPLACE
                 * so that the new attr doesn't fit in shortform format, the
                 * leaf format add routine won't trip over the attr not being
                 * around.
                 */
                args->op_flags &= ~XFS_DA_OP_REPLACE;
        } else {
                ASSERT(!(args->op_flags & XFS_DA_OP_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
 *========================================================================*/

/* Save the current remote block info and clear the current pointers. */
static void
xfs_attr_save_rmt_blk(
        struct xfs_da_args      *args)
{
        args->blkno2 = args->blkno;
        args->index2 = args->index;
        args->rmtblkno2 = args->rmtblkno;
        args->rmtblkcnt2 = args->rmtblkcnt;
        args->rmtvaluelen2 = args->rmtvaluelen;
        args->rmtblkno = 0;
        args->rmtblkcnt = 0;
        args->rmtvaluelen = 0;
}

/* Set stored info about a remote block */
static void
xfs_attr_restore_rmt_blk(
        struct xfs_da_args      *args)
{
        args->blkno = args->blkno2;
        args->index = args->index2;
        args->rmtblkno = args->rmtblkno2;
        args->rmtblkcnt = args->rmtblkcnt2;
        args->rmtvaluelen = args->rmtvaluelen2;
}

/*
 * Tries to add an attribute to an inode in leaf form
 *
 * This function is meant to execute as part of a delayed operation and leaves
 * the transaction handling to the caller.  On success the attribute is added
 * and the inode and transaction are left dirty.  If there is not enough space,
 * the attr data is converted to node format and -ENOSPC is returned. Caller is
 * responsible for handling the dirty inode and transaction or adding the attr
 * in node format.
 */
STATIC int
xfs_attr_leaf_try_add(
        struct xfs_da_args      *args)
{
        struct xfs_buf          *bp;
        int                     error;

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

        /*
         * Look up the xattr name to set the insertion point for the new xattr.
         */
        error = xfs_attr3_leaf_lookup_int(bp, args);
        switch (error) {
        case -ENOATTR:
                if (args->op_flags & XFS_DA_OP_REPLACE)
                        goto out_brelse;
                break;
        case -EEXIST:
                if (!(args->op_flags & XFS_DA_OP_REPLACE))
                        goto out_brelse;

                trace_xfs_attr_leaf_replace(args);
                /*
                 * Save the existing remote attr state so that the current
                 * values reflect the state of the new attribute we are about to
                 * add, not the attribute we just found and will remove later.
                 */
                xfs_attr_save_rmt_blk(args);
                break;
        case 0:
                break;
        default:
                goto out_brelse;
        }

        return xfs_attr3_leaf_add(bp, args);

out_brelse:
        xfs_trans_brelse(args->trans, bp);
        return error;
}

/*
 * Return EEXIST if attr is found, or ENOATTR if not
 */
STATIC int
xfs_attr_leaf_hasname(
        struct xfs_da_args      *args,
        struct xfs_buf          **bp)
{
        int                     error = 0;

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

        error = xfs_attr3_leaf_lookup_int(*bp, args);
        if (error != -ENOATTR && error != -EEXIST)
                xfs_trans_brelse(args->trans, *bp);

        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;

        error = xfs_attr_leaf_hasname(args, &bp);
        if (error == -ENOATTR) {
                xfs_trans_brelse(args->trans, bp);
                if (args->op_flags & XFS_DA_OP_RECOVERY)
                        return 0;
                return error;
        } else if (error != -EEXIST)
                return error;

        xfs_attr3_leaf_remove(bp, args);

        /*
         * If the result is small enough, shrink it all into the inode.
         */
        forkoff = xfs_attr_shortform_allfit(bp, dp);
        if (forkoff)
                return xfs_attr3_leaf_to_shortform(bp, args, forkoff);
                /* bp is gone due to xfs_da_shrink_inode */

        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);

        error = xfs_attr_leaf_hasname(args, &bp);

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


        error = xfs_attr3_leaf_getvalue(bp, args);
        xfs_trans_brelse(args->trans, bp);
        return error;
}

/* Return EEXIST if attr is found, or ENOATTR if not. */
STATIC int
xfs_attr_node_lookup(
        struct xfs_da_args      *args,
        struct xfs_da_state     *state)
{
        int                     retval, error;

        /*
         * Search to see if name exists, and get back a pointer to it.
         */
        error = xfs_da3_node_lookup_int(state, &retval);
        if (error)
                return error;

        return retval;
}

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

STATIC int
xfs_attr_node_addname_find_attr(
         struct xfs_attr_intent *attr)
{
        struct xfs_da_args      *args = attr->xattri_da_args;
        int                     error;

        /*
         * Search to see if name already exists, and get back a pointer
         * to where it should go.
         */
        xfs_attr_item_init_da_state(attr);
        error = xfs_attr_node_lookup(args, attr->xattri_da_state);
        switch (error) {
        case -ENOATTR:
                if (args->op_flags & XFS_DA_OP_REPLACE)
                        goto error;
                break;
        case -EEXIST:
                if (!(args->op_flags & XFS_DA_OP_REPLACE))
                        goto error;


                trace_xfs_attr_node_replace(args);
                /*
                 * Save the existing remote attr state so that the current
                 * values reflect the state of the new attribute we are about to
                 * add, not the attribute we just found and will remove later.
                 */
                xfs_attr_save_rmt_blk(args);
                break;
        case 0:
                break;
        default:
                goto error;
        }

        return 0;
error:
        if (attr->xattri_da_state) {
                xfs_da_state_free(attr->xattri_da_state);
                attr->xattri_da_state = NULL;
        }
        return error;
}

/*
 * 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).
 */
static int
xfs_attr_node_try_addname(
        struct xfs_attr_intent          *attr)
{
        struct xfs_da_state             *state = attr->xattri_da_state;
        struct xfs_da_state_blk         *blk;
        int                             error;

        trace_xfs_attr_node_addname(state->args);

        blk = &state->path.blk[state->path.active-1];
        ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);

        error = xfs_attr3_leaf_add(blk->bp, state->args);
        if (error == -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. Let the caller deal with this.
                         */
                        goto out;
                }

                /*
                 * 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;
        } else {
                /*
                 * Addition succeeded, update Btree hashvals.
                 */
                xfs_da3_fixhashpath(state, &state->path);
        }

out:
        xfs_da_state_free(state);
        attr->xattri_da_state = NULL;
        return error;
}

static int
xfs_attr_node_removename(
        struct xfs_da_args      *args,
        struct xfs_da_state     *state)
{
        struct xfs_da_state_blk *blk;
        int                     retval;

        /*
         * 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);

        return retval;
}

static int
xfs_attr_node_remove_attr(
        struct xfs_attr_intent          *attr)
{
        struct xfs_da_args              *args = attr->xattri_da_args;
        struct xfs_da_state             *state = xfs_da_state_alloc(args);
        int                             retval = 0;
        int                             error = 0;

        /*
         * The attr we are removing has already been marked incomplete, so
         * we need to set the filter appropriately to re-find the "old"
         * attribute entry after any split ops.
         */
        args->attr_filter |= XFS_ATTR_INCOMPLETE;
        error = xfs_da3_node_lookup_int(state, &retval);
        if (error)
                goto out;

        error = xfs_attr_node_removename(args, state);

        /*
         * 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;
        }
        retval = error = 0;

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

/*
 * 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(
        struct xfs_da_args      *args)
{
        struct xfs_da_state     *state;
        struct xfs_da_state_blk *blk;
        int                     i;
        int                     error;

        trace_xfs_attr_node_get(args);

        /*
         * Search to see if name exists, and get back a pointer to it.
         */
        state = xfs_da_state_alloc(args);
        error = xfs_attr_node_lookup(args, state);
        if (error != -EEXIST)
                goto out_release;

        /*
         * Get the value, local or "remote"
         */
        blk = &state->path.blk[state->path.active - 1];
        error = 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 error;
}

/* 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);
}

int __init
xfs_attr_intent_init_cache(void)
{
        xfs_attr_intent_cache = kmem_cache_create("xfs_attr_intent",
                        sizeof(struct xfs_attr_intent),
                        0, 0, NULL);

        return xfs_attr_intent_cache != NULL ? 0 : -ENOMEM;
}

void
xfs_attr_intent_destroy_cache(void)
{
        kmem_cache_destroy(xfs_attr_intent_cache);
        xfs_attr_intent_cache = NULL;
}