xref: /linux/fs/xfs/libxfs/xfs_attr.c (revision b3f4e84e)

// 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"
#include "xfs_parent.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);

/*
 * 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;

	ASSERT(!xfs_need_iread_extents(ifp));

	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)
{
	int			error;

	xfs_assert_ilocked(args->dp, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL);

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

	/*
	 * The incore attr fork iext tree must be loaded for xfs_attr_is_leaf
	 * to work correctly.
	 */
	error = xfs_iread_extents(args->trans, args->dp, XFS_ATTR_FORK);
	if (error)
		return error;

	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;

	if (!args->owner)
		args->owner = args->dp->i_ino;
	args->geo = args->dp->i_mount->m_attr_geo;
	args->whichfork = XFS_ATTR_FORK;
	xfs_attr_sethash(args);

	/* 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 an xattr set/replace/upsert */
inline struct xfs_trans_res
xfs_attr_set_resv(
	const struct xfs_da_args	*args)
{
	struct xfs_mount		*mp = args->dp->i_mount;
	struct xfs_trans_res		ret = {
		.tr_logres = M_RES(mp)->tr_attrsetm.tr_logres +
			    M_RES(mp)->tr_attrsetrt.tr_logres * args->total,
		.tr_logcount		= XFS_ATTRSET_LOG_COUNT,
		.tr_logflags		= XFS_TRANS_PERM_LOG_RES,
	};

	return ret;
}

/*
 * 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)
		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;
}

/* Compute the hash value for a user/root/secure extended attribute */
xfs_dahash_t
xfs_attr_hashname(
	const uint8_t		*name,
	int			namelen)
{
	return xfs_da_hashname(name, namelen);
}

/* Compute the hash value for any extended attribute from any namespace. */
xfs_dahash_t
xfs_attr_hashval(
	struct xfs_mount	*mp,
	unsigned int		attr_flags,
	const uint8_t		*name,
	int			namelen,
	const void		*value,
	int			valuelen)
{
	ASSERT(xfs_attr_check_namespace(attr_flags));

	if (attr_flags & XFS_ATTR_PARENT)
		return xfs_parent_hashattr(mp, name, namelen, value, valuelen);

	return xfs_attr_hashname(name, namelen);
}

/* 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;
}

/*
 * PPTR_REPLACE operations require the caller to set the old and new names and
 * values explicitly.  Update the canonical fields to the new name and value
 * here now that the removal phase has finished.
 */
static void
xfs_attr_update_pptr_replace_args(
	struct xfs_da_args	*args)
{
	ASSERT(args->new_namelen > 0);
	args->name = args->new_name;
	args->namelen = args->new_namelen;
	args->value = args->new_value;
	args->valuelen = args->new_valuelen;
	xfs_attr_sethash(args);
}

/*
 * 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;

	if (!(args->op_flags & XFS_DA_OP_REPLACE))
		replace_state = XFS_DAS_DONE;
	else if (xfs_attr_intent_op(attr) == XFS_ATTRI_OP_FLAGS_PPTR_REPLACE)
		xfs_attr_update_pptr_replace_args(args);

	args->op_flags &= ~XFS_DA_OP_REPLACE;
	args->attr_filter &= ~XFS_ATTR_INCOMPLETE;
	return replace_state;
}

/*
 * Try to add an attribute to an inode in leaf form.
 */
static int
xfs_attr_leaf_addname(
	struct xfs_attr_intent	*attr)
{
	struct xfs_da_args	*args = attr->xattri_da_args;
	struct xfs_buf		*bp;
	int			error;

	ASSERT(xfs_attr_is_leaf(args->dp));

	error = xfs_attr3_leaf_read(args->trans, args->dp, args->owner, 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;
	}

	/*
	 * 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 (!xfs_attr3_leaf_add(bp, args)) {
		error = xfs_attr3_leaf_to_node(args);
		if (error)
			return error;

		attr->xattri_dela_state = XFS_DAS_NODE_ADD;
	} else 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);
	}

	trace_xfs_attr_leaf_addname_return(attr->xattri_dela_state, args->dp);
	return 0;

out_brelse:
	xfs_trans_brelse(args->trans, bp);
	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 == 1) {
		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->owner,
			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, args->owner, 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;
	}

	/* Prerequisite for xfs_attr_is_leaf */
	error = xfs_iread_extents(args->trans, args->dp, XFS_ATTR_FORK);
	if (error)
		return error;

	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;
}

int
xfs_attr_add_fork(
	struct xfs_inode	*ip,		/* incore inode pointer */
	int			size,		/* space new attribute needs */
	int			rsvd)		/* xact may use reserved blks */
{
	struct xfs_mount	*mp = ip->i_mount;
	struct xfs_trans	*tp;		/* transaction pointer */
	unsigned int		blks;		/* space reservation */
	int			error;		/* error return value */

	ASSERT(!XFS_NOT_DQATTACHED(mp, ip));

	blks = XFS_ADDAFORK_SPACE_RES(mp);

	error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_addafork, blks, 0,
			rsvd, &tp);
	if (error)
		return error;

	if (xfs_inode_has_attr_fork(ip))
		goto trans_cancel;

	error = xfs_bmap_add_attrfork(tp, ip, size, rsvd);
	if (error)
		goto trans_cancel;

	error = xfs_trans_commit(tp);
	xfs_iunlock(ip, XFS_ILOCK_EXCL);
	return error;

trans_cancel:
	xfs_trans_cancel(tp);
	xfs_iunlock(ip, XFS_ILOCK_EXCL);
	return error;
}

/*
 * Make a change to the xattr structure.
 *
 * The caller must have initialized @args, attached dquots, and must not hold
 * any ILOCKs.  Reserved data blocks may be used if @rsvd is set.
 *
 * Returns -EEXIST for XFS_ATTRUPDATE_CREATE if the name already exists.
 * Returns -ENOATTR for XFS_ATTRUPDATE_REMOVE if the name does not exist.
 * Returns 0 on success, or a negative errno if something else went wrong.
 */
int
xfs_attr_set(
	struct xfs_da_args	*args,
	enum xfs_attr_update	op,
	bool			rsvd)
{
	struct xfs_inode	*dp = args->dp;
	struct xfs_mount	*mp = dp->i_mount;
	struct xfs_trans_res	tres;
	int			error, local;
	int			rmt_blks = 0;
	unsigned int		total = 0;

	ASSERT(!args->trans);

	switch (op) {
	case XFS_ATTRUPDATE_UPSERT:
	case XFS_ATTRUPDATE_CREATE:
	case XFS_ATTRUPDATE_REPLACE:
		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_attr_add_fork(dp, sf_size, rsvd);
			if (error)
				return error;
		}

		if (!local)
			rmt_blks = xfs_attr3_rmt_blocks(mp, args->valuelen);

		tres = xfs_attr_set_resv(args);
		total = args->total;
		break;
	case XFS_ATTRUPDATE_REMOVE:
		XFS_STATS_INC(mp, xs_attr_remove);
		rmt_blks = xfs_attr3_max_rmt_blocks(mp);
		tres = M_RES(mp)->tr_attrrm;
		total = XFS_ATTRRM_SPACE_RES(mp);
		break;
	}

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

	if (op != XFS_ATTRUPDATE_REMOVE || xfs_inode_hasattr(dp)) {
		error = xfs_iext_count_extend(args->trans, dp, XFS_ATTR_FORK,
				XFS_IEXT_ATTR_MANIP_CNT(rmt_blks));
		if (error)
			goto out_trans_cancel;
	}

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

		/* Pure create fails if the attr already exists */
		if (op == XFS_ATTRUPDATE_CREATE)
			goto out_trans_cancel;
		xfs_attr_defer_add(args, XFS_ATTR_DEFER_REPLACE);
		break;
	case -ENOATTR:
		/* Can't remove what isn't there. */
		if (op == XFS_ATTRUPDATE_REMOVE)
			goto out_trans_cancel;

		/* Pure replace fails if no existing attr to replace. */
		if (op == XFS_ATTRUPDATE_REPLACE)
			goto out_trans_cancel;
		xfs_attr_defer_add(args, XFS_ATTR_DEFER_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);

	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);
	args->trans = NULL;
	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
 *========================================================================*/

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
 *========================================================================*/

/*
 * 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, args->owner, 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).
 *
 * If the tree was still in single leaf format and needs to converted to
 * real node format return 1 and let the caller handle that.
 */
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 = 0;

	trace_xfs_attr_node_addname(state->args);

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

	if (!xfs_attr3_leaf_add(blk->bp, state->args)) {
		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.
			 */
			error = 1;
			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;
}

/* Enforce that there is at most one namespace bit per attr. */
inline bool xfs_attr_check_namespace(unsigned int attr_flags)
{
	return hweight32(attr_flags & XFS_ATTR_NSP_ONDISK_MASK) < 2;
}

/* Returns true if the attribute entry name is valid. */
bool
xfs_attr_namecheck(
	unsigned int	attr_flags,
	const void	*name,
	size_t		length)
{
	/* Only one namespace bit allowed. */
	if (!xfs_attr_check_namespace(attr_flags))
		return false;

	/*
	 * MAXNAMELEN includes the trailing null, but (name/length) leave it
	 * out, so use >= for the length check.
	 */
	if (length >= MAXNAMELEN)
		return false;

	/* Parent pointers have their own validation. */
	if (attr_flags & XFS_ATTR_PARENT)
		return xfs_parent_namecheck(attr_flags, name, length);

	/* 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;
}