xfs: remove xfs_iget.c (33479e05) · Commits · e / devices / android_kernel_xiaomi_markw

fs/xfs/Makefile

+0 −1

Original line number	Diff line number	Diff line
		@@ -40,7 +40,6 @@ xfs-y += xfs_aops.o \
		xfs_fs_subr.o \
		xfs_globals.o \
		xfs_icache.o \
		xfs_iget.o \
		xfs_ioctl.o \
		xfs_iomap.o \
		xfs_iops.o \

fs/xfs/xfs_export.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -29,6 +29,7 @@
		#include "xfs_inode.h"
		#include "xfs_inode_item.h"
		#include "xfs_trace.h"
		#include "xfs_icache.h"

		/*
		* Note that we only accept fileids which are long enough rather than allow

fs/xfs/xfs_icache.c

+418 −3

Original line number	Diff line number	Diff line
		@@ -41,6 +41,421 @@
		#include <linux/kthread.h>
		#include <linux/freezer.h>

		STATIC void __xfs_inode_clear_reclaim_tag(struct xfs_mount *mp,
		struct xfs_perag pag, struct xfs_inode ip);

		/*
		* Allocate and initialise an xfs_inode.
		*/
		STATIC struct xfs_inode *
		xfs_inode_alloc(
		struct xfs_mount *mp,
		xfs_ino_t ino)
		{
		struct xfs_inode *ip;

		/*
		* if this didn't occur in transactions, we could use
		* KM_MAYFAIL and return NULL here on ENOMEM. Set the
		* code up to do this anyway.
		*/
		ip = kmem_zone_alloc(xfs_inode_zone, KM_SLEEP);
		if (!ip)
		return NULL;
		if (inode_init_always(mp->m_super, VFS_I(ip))) {
		kmem_zone_free(xfs_inode_zone, ip);
		return NULL;
		}

		ASSERT(atomic_read(&ip->i_pincount) == 0);
		ASSERT(!spin_is_locked(&ip->i_flags_lock));
		ASSERT(!xfs_isiflocked(ip));
		ASSERT(ip->i_ino == 0);

		mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", ip->i_ino);

		/* initialise the xfs inode */
		ip->i_ino = ino;
		ip->i_mount = mp;
		memset(&ip->i_imap, 0, sizeof(struct xfs_imap));
		ip->i_afp = NULL;
		memset(&ip->i_df, 0, sizeof(xfs_ifork_t));
		ip->i_flags = 0;
		ip->i_delayed_blks = 0;
		memset(&ip->i_d, 0, sizeof(xfs_icdinode_t));

		return ip;
		}

		STATIC void
		xfs_inode_free_callback(
		struct rcu_head *head)
		{
		struct inode *inode = container_of(head, struct inode, i_rcu);
		struct xfs_inode *ip = XFS_I(inode);

		kmem_zone_free(xfs_inode_zone, ip);
		}

		STATIC void
		xfs_inode_free(
		struct xfs_inode *ip)
		{
		switch (ip->i_d.di_mode & S_IFMT) {
		case S_IFREG:
		case S_IFDIR:
		case S_IFLNK:
		xfs_idestroy_fork(ip, XFS_DATA_FORK);
		break;
		}

		if (ip->i_afp)
		xfs_idestroy_fork(ip, XFS_ATTR_FORK);

		if (ip->i_itemp) {
		ASSERT(!(ip->i_itemp->ili_item.li_flags & XFS_LI_IN_AIL));
		xfs_inode_item_destroy(ip);
		ip->i_itemp = NULL;
		}

		/* asserts to verify all state is correct here */
		ASSERT(atomic_read(&ip->i_pincount) == 0);
		ASSERT(!spin_is_locked(&ip->i_flags_lock));
		ASSERT(!xfs_isiflocked(ip));

		/*
		* Because we use RCU freeing we need to ensure the inode always
		* appears to be reclaimed with an invalid inode number when in the
		* free state. The ip->i_flags_lock provides the barrier against lookup
		* races.
		*/
		spin_lock(&ip->i_flags_lock);
		ip->i_flags = XFS_IRECLAIM;
		ip->i_ino = 0;
		spin_unlock(&ip->i_flags_lock);

		call_rcu(&VFS_I(ip)->i_rcu, xfs_inode_free_callback);
		}

		/*
		* Check the validity of the inode we just found it the cache
		*/
		static int
		xfs_iget_cache_hit(
		struct xfs_perag *pag,
		struct xfs_inode *ip,
		xfs_ino_t ino,
		int flags,
		int lock_flags) __releases(RCU)
		{
		struct inode *inode = VFS_I(ip);
		struct xfs_mount *mp = ip->i_mount;
		int error;

		/*
		* check for re-use of an inode within an RCU grace period due to the
		* radix tree nodes not being updated yet. We monitor for this by
		* setting the inode number to zero before freeing the inode structure.
		* If the inode has been reallocated and set up, then the inode number
		* will not match, so check for that, too.
		*/
		spin_lock(&ip->i_flags_lock);
		if (ip->i_ino != ino) {
		trace_xfs_iget_skip(ip);
		XFS_STATS_INC(xs_ig_frecycle);
		error = EAGAIN;
		goto out_error;
		}


		/*
		* If we are racing with another cache hit that is currently
		* instantiating this inode or currently recycling it out of
		* reclaimabe state, wait for the initialisation to complete
		* before continuing.
		*
		* XXX(hch): eventually we should do something equivalent to
		* wait_on_inode to wait for these flags to be cleared
		* instead of polling for it.
		*/
		if (ip->i_flags & (XFS_INEW\|XFS_IRECLAIM)) {
		trace_xfs_iget_skip(ip);
		XFS_STATS_INC(xs_ig_frecycle);
		error = EAGAIN;
		goto out_error;
		}

		/*
		* If lookup is racing with unlink return an error immediately.
		*/
		if (ip->i_d.di_mode == 0 && !(flags & XFS_IGET_CREATE)) {
		error = ENOENT;
		goto out_error;
		}

		/*
		* If IRECLAIMABLE is set, we've torn down the VFS inode already.
		* Need to carefully get it back into useable state.
		*/
		if (ip->i_flags & XFS_IRECLAIMABLE) {
		trace_xfs_iget_reclaim(ip);

		/*
		* We need to set XFS_IRECLAIM to prevent xfs_reclaim_inode
		* from stomping over us while we recycle the inode. We can't
		* clear the radix tree reclaimable tag yet as it requires
		* pag_ici_lock to be held exclusive.
		*/
		ip->i_flags \|= XFS_IRECLAIM;

		spin_unlock(&ip->i_flags_lock);
		rcu_read_unlock();

		error = -inode_init_always(mp->m_super, inode);
		if (error) {
		/*
		* Re-initializing the inode failed, and we are in deep
		* trouble. Try to re-add it to the reclaim list.
		*/
		rcu_read_lock();
		spin_lock(&ip->i_flags_lock);

		ip->i_flags &= ~(XFS_INEW \| XFS_IRECLAIM);
		ASSERT(ip->i_flags & XFS_IRECLAIMABLE);
		trace_xfs_iget_reclaim_fail(ip);
		goto out_error;
		}

		spin_lock(&pag->pag_ici_lock);
		spin_lock(&ip->i_flags_lock);

		/*
		* Clear the per-lifetime state in the inode as we are now
		* effectively a new inode and need to return to the initial
		* state before reuse occurs.
		*/
		ip->i_flags &= ~XFS_IRECLAIM_RESET_FLAGS;
		ip->i_flags \|= XFS_INEW;
		__xfs_inode_clear_reclaim_tag(mp, pag, ip);
		inode->i_state = I_NEW;

		ASSERT(!rwsem_is_locked(&ip->i_iolock.mr_lock));
		mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", ip->i_ino);

		spin_unlock(&ip->i_flags_lock);
		spin_unlock(&pag->pag_ici_lock);
		} else {
		/* If the VFS inode is being torn down, pause and try again. */
		if (!igrab(inode)) {
		trace_xfs_iget_skip(ip);
		error = EAGAIN;
		goto out_error;
		}

		/* We've got a live one. */
		spin_unlock(&ip->i_flags_lock);
		rcu_read_unlock();
		trace_xfs_iget_hit(ip);
		}

		if (lock_flags != 0)
		xfs_ilock(ip, lock_flags);

		xfs_iflags_clear(ip, XFS_ISTALE \| XFS_IDONTCACHE);
		XFS_STATS_INC(xs_ig_found);

		return 0;

		out_error:
		spin_unlock(&ip->i_flags_lock);
		rcu_read_unlock();
		return error;
		}


		static int
		xfs_iget_cache_miss(
		struct xfs_mount *mp,
		struct xfs_perag *pag,
		xfs_trans_t *tp,
		xfs_ino_t ino,
		struct xfs_inode **ipp,
		int flags,
		int lock_flags)
		{
		struct xfs_inode *ip;
		int error;
		xfs_agino_t agino = XFS_INO_TO_AGINO(mp, ino);
		int iflags;

		ip = xfs_inode_alloc(mp, ino);
		if (!ip)
		return ENOMEM;

		error = xfs_iread(mp, tp, ip, flags);
		if (error)
		goto out_destroy;

		trace_xfs_iget_miss(ip);

		if ((ip->i_d.di_mode == 0) && !(flags & XFS_IGET_CREATE)) {
		error = ENOENT;
		goto out_destroy;
		}

		/*
		* Preload the radix tree so we can insert safely under the
		* write spinlock. Note that we cannot sleep inside the preload
		* region. Since we can be called from transaction context, don't
		* recurse into the file system.
		*/
		if (radix_tree_preload(GFP_NOFS)) {
		error = EAGAIN;
		goto out_destroy;
		}

		/*
		* Because the inode hasn't been added to the radix-tree yet it can't
		* be found by another thread, so we can do the non-sleeping lock here.
		*/
		if (lock_flags) {
		if (!xfs_ilock_nowait(ip, lock_flags))
		BUG();
		}

		/*
		* These values must be set before inserting the inode into the radix
		* tree as the moment it is inserted a concurrent lookup (allowed by the
		* RCU locking mechanism) can find it and that lookup must see that this
		* is an inode currently under construction (i.e. that XFS_INEW is set).
		* The ip->i_flags_lock that protects the XFS_INEW flag forms the
		* memory barrier that ensures this detection works correctly at lookup
		* time.
		*/
		iflags = XFS_INEW;
		if (flags & XFS_IGET_DONTCACHE)
		iflags \|= XFS_IDONTCACHE;
		ip->i_udquot = ip->i_gdquot = NULL;
		xfs_iflags_set(ip, iflags);

		/* insert the new inode */
		spin_lock(&pag->pag_ici_lock);
		error = radix_tree_insert(&pag->pag_ici_root, agino, ip);
		if (unlikely(error)) {
		WARN_ON(error != -EEXIST);
		XFS_STATS_INC(xs_ig_dup);
		error = EAGAIN;
		goto out_preload_end;
		}
		spin_unlock(&pag->pag_ici_lock);
		radix_tree_preload_end();

		*ipp = ip;
		return 0;

		out_preload_end:
		spin_unlock(&pag->pag_ici_lock);
		radix_tree_preload_end();
		if (lock_flags)
		xfs_iunlock(ip, lock_flags);
		out_destroy:
		__destroy_inode(VFS_I(ip));
		xfs_inode_free(ip);
		return error;
		}

		/*
		* Look up an inode by number in the given file system.
		* The inode is looked up in the cache held in each AG.
		* If the inode is found in the cache, initialise the vfs inode
		* if necessary.
		*
		* If it is not in core, read it in from the file system's device,
		* add it to the cache and initialise the vfs inode.
		*
		* The inode is locked according to the value of the lock_flags parameter.
		* This flag parameter indicates how and if the inode's IO lock and inode lock
		* should be taken.
		*
		* mp -- the mount point structure for the current file system. It points
		* to the inode hash table.
		* tp -- a pointer to the current transaction if there is one. This is
		* simply passed through to the xfs_iread() call.
		* ino -- the number of the inode desired. This is the unique identifier
		* within the file system for the inode being requested.
		* lock_flags -- flags indicating how to lock the inode. See the comment
		* for xfs_ilock() for a list of valid values.
		*/
		int
		xfs_iget(
		xfs_mount_t *mp,
		xfs_trans_t *tp,
		xfs_ino_t ino,
		uint flags,
		uint lock_flags,
		xfs_inode_t **ipp)
		{
		xfs_inode_t *ip;
		int error;
		xfs_perag_t *pag;
		xfs_agino_t agino;

		/*
		* xfs_reclaim_inode() uses the ILOCK to ensure an inode
		* doesn't get freed while it's being referenced during a
		* radix tree traversal here. It assumes this function
		* aqcuires only the ILOCK (and therefore it has no need to
		* involve the IOLOCK in this synchronization).
		*/
		ASSERT((lock_flags & (XFS_IOLOCK_EXCL \| XFS_IOLOCK_SHARED)) == 0);

		/* reject inode numbers outside existing AGs */
		if (!ino \|\| XFS_INO_TO_AGNO(mp, ino) >= mp->m_sb.sb_agcount)
		return EINVAL;

		/* get the perag structure and ensure that it's inode capable */
		pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ino));
		agino = XFS_INO_TO_AGINO(mp, ino);

		again:
		error = 0;
		rcu_read_lock();
		ip = radix_tree_lookup(&pag->pag_ici_root, agino);

		if (ip) {
		error = xfs_iget_cache_hit(pag, ip, ino, flags, lock_flags);
		if (error)
		goto out_error_or_again;
		} else {
		rcu_read_unlock();
		XFS_STATS_INC(xs_ig_missed);

		error = xfs_iget_cache_miss(mp, pag, tp, ino, &ip,
		flags, lock_flags);
		if (error)
		goto out_error_or_again;
		}
		xfs_perag_put(pag);

		*ipp = ip;

		/*
		* If we have a real type for an on-disk inode, we can set ops(&unlock)
		* now. If it's a new inode being created, xfs_ialloc will handle it.
		*/
		if (xfs_iflags_test(ip, XFS_INEW) && ip->i_d.di_mode != 0)
		xfs_setup_inode(ip);
		return 0;

		out_error_or_again:
		if (error == EAGAIN) {
		delay(1);
		goto again;
		}
		xfs_perag_put(pag);
		return error;
		}

		/*
		* The inode lookup is done in batches to keep the amount of lock traffic and
		* radix tree lookups to a minimum. The batch size is a trade off between
		@@ -253,7 +668,7 @@ xfs_reclaim_worker(
		xfs_reclaim_work_queue(mp);
		}

		void
		static void
		__xfs_inode_set_reclaim_tag(
		struct xfs_perag *pag,
		struct xfs_inode *ip)
		@@ -319,7 +734,7 @@ __xfs_inode_clear_reclaim(
		}
		}

		void
		STATIC void
		__xfs_inode_clear_reclaim_tag(
		xfs_mount_t *mp,
		xfs_perag_t *pag,
		@@ -542,7 +957,7 @@ out:
		* then a shut down during filesystem unmount reclaim walk leak all the
		* unreclaimed inodes.
		*/
		int
		STATIC int
		xfs_reclaim_inodes_ag(
		struct xfs_mount *mp,
		int flags,

fs/xfs/xfs_icache.h

+3 −3

Original line number	Diff line number	Diff line
		@@ -24,6 +24,9 @@ struct xfs_perag;
		#define SYNC_WAIT 0x0001 /* wait for i/o to complete */
		#define SYNC_TRYLOCK 0x0002 /* only try to lock inodes */

		int xfs_iget(struct xfs_mount mp, struct xfs_trans tp, xfs_ino_t ino,
		uint flags, uint lock_flags, xfs_inode_t **ipp);

		void xfs_reclaim_worker(struct work_struct *work);

		int xfs_reclaim_inodes(struct xfs_mount *mp, int mode);
		@@ -31,9 +34,6 @@ int xfs_reclaim_inodes_count(struct xfs_mount *mp);
		void xfs_reclaim_inodes_nr(struct xfs_mount *mp, int nr_to_scan);

		void xfs_inode_set_reclaim_tag(struct xfs_inode *ip);
		void __xfs_inode_set_reclaim_tag(struct xfs_perag pag, struct xfs_inode ip);
		void __xfs_inode_clear_reclaim_tag(struct xfs_mount mp, struct xfs_perag pag,
		struct xfs_inode *ip);

		int xfs_sync_inode_grab(struct xfs_inode *ip);
		int xfs_inode_ag_iterator(struct xfs_mount *mp,

fs/xfs/xfs_iget.c

deleted100644 → 0

+0 −455

Original line number	Diff line number	Diff line
		/*
		* Copyright (c) 2000-2005 Silicon Graphics, Inc.
		* All Rights Reserved.
		*
		* This program is free software; you can redistribute it and/or
		* modify it under the terms of the GNU General Public License as
		* published by the Free Software Foundation.
		*
		* This program is distributed in the hope that it would be useful,
		* but WITHOUT ANY WARRANTY; without even the implied warranty of
		* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
		* GNU General Public License for more details.
		*
		* You should have received a copy of the GNU General Public License
		* along with this program; if not, write the Free Software Foundation,
		* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
		*/
		#include "xfs.h"
		#include "xfs_fs.h"
		#include "xfs_types.h"
		#include "xfs_acl.h"
		#include "xfs_log.h"
		#include "xfs_inum.h"
		#include "xfs_trans.h"
		#include "xfs_sb.h"
		#include "xfs_ag.h"
		#include "xfs_mount.h"
		#include "xfs_bmap_btree.h"
		#include "xfs_alloc_btree.h"
		#include "xfs_ialloc_btree.h"
		#include "xfs_dinode.h"
		#include "xfs_inode.h"
		#include "xfs_btree.h"
		#include "xfs_ialloc.h"
		#include "xfs_quota.h"
		#include "xfs_utils.h"
		#include "xfs_trans_priv.h"
		#include "xfs_inode_item.h"
		#include "xfs_bmap.h"
		#include "xfs_trace.h"
		#include "xfs_icache.h"


		/*
		* Allocate and initialise an xfs_inode.
		*/
		STATIC struct xfs_inode *
		xfs_inode_alloc(
		struct xfs_mount *mp,
		xfs_ino_t ino)
		{
		struct xfs_inode *ip;

		/*
		* if this didn't occur in transactions, we could use
		* KM_MAYFAIL and return NULL here on ENOMEM. Set the
		* code up to do this anyway.
		*/
		ip = kmem_zone_alloc(xfs_inode_zone, KM_SLEEP);
		if (!ip)
		return NULL;
		if (inode_init_always(mp->m_super, VFS_I(ip))) {
		kmem_zone_free(xfs_inode_zone, ip);
		return NULL;
		}

		ASSERT(atomic_read(&ip->i_pincount) == 0);
		ASSERT(!spin_is_locked(&ip->i_flags_lock));
		ASSERT(!xfs_isiflocked(ip));
		ASSERT(ip->i_ino == 0);

		mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", ip->i_ino);

		/* initialise the xfs inode */
		ip->i_ino = ino;
		ip->i_mount = mp;
		memset(&ip->i_imap, 0, sizeof(struct xfs_imap));
		ip->i_afp = NULL;
		memset(&ip->i_df, 0, sizeof(xfs_ifork_t));
		ip->i_flags = 0;
		ip->i_delayed_blks = 0;
		memset(&ip->i_d, 0, sizeof(xfs_icdinode_t));

		return ip;
		}

		STATIC void
		xfs_inode_free_callback(
		struct rcu_head *head)
		{
		struct inode *inode = container_of(head, struct inode, i_rcu);
		struct xfs_inode *ip = XFS_I(inode);

		kmem_zone_free(xfs_inode_zone, ip);
		}

		void
		xfs_inode_free(
		struct xfs_inode *ip)
		{
		switch (ip->i_d.di_mode & S_IFMT) {
		case S_IFREG:
		case S_IFDIR:
		case S_IFLNK:
		xfs_idestroy_fork(ip, XFS_DATA_FORK);
		break;
		}

		if (ip->i_afp)
		xfs_idestroy_fork(ip, XFS_ATTR_FORK);

		if (ip->i_itemp) {
		ASSERT(!(ip->i_itemp->ili_item.li_flags & XFS_LI_IN_AIL));
		xfs_inode_item_destroy(ip);
		ip->i_itemp = NULL;
		}

		/* asserts to verify all state is correct here */
		ASSERT(atomic_read(&ip->i_pincount) == 0);
		ASSERT(!spin_is_locked(&ip->i_flags_lock));
		ASSERT(!xfs_isiflocked(ip));

		/*
		* Because we use RCU freeing we need to ensure the inode always
		* appears to be reclaimed with an invalid inode number when in the
		* free state. The ip->i_flags_lock provides the barrier against lookup
		* races.
		*/
		spin_lock(&ip->i_flags_lock);
		ip->i_flags = XFS_IRECLAIM;
		ip->i_ino = 0;
		spin_unlock(&ip->i_flags_lock);

		call_rcu(&VFS_I(ip)->i_rcu, xfs_inode_free_callback);
		}

		/*
		* Check the validity of the inode we just found it the cache
		*/
		static int
		xfs_iget_cache_hit(
		struct xfs_perag *pag,
		struct xfs_inode *ip,
		xfs_ino_t ino,
		int flags,
		int lock_flags) __releases(RCU)
		{
		struct inode *inode = VFS_I(ip);
		struct xfs_mount *mp = ip->i_mount;
		int error;

		/*
		* check for re-use of an inode within an RCU grace period due to the
		* radix tree nodes not being updated yet. We monitor for this by
		* setting the inode number to zero before freeing the inode structure.
		* If the inode has been reallocated and set up, then the inode number
		* will not match, so check for that, too.
		*/
		spin_lock(&ip->i_flags_lock);
		if (ip->i_ino != ino) {
		trace_xfs_iget_skip(ip);
		XFS_STATS_INC(xs_ig_frecycle);
		error = EAGAIN;
		goto out_error;
		}


		/*
		* If we are racing with another cache hit that is currently
		* instantiating this inode or currently recycling it out of
		* reclaimabe state, wait for the initialisation to complete
		* before continuing.
		*
		* XXX(hch): eventually we should do something equivalent to
		* wait_on_inode to wait for these flags to be cleared
		* instead of polling for it.
		*/
		if (ip->i_flags & (XFS_INEW\|XFS_IRECLAIM)) {
		trace_xfs_iget_skip(ip);
		XFS_STATS_INC(xs_ig_frecycle);
		error = EAGAIN;
		goto out_error;
		}

		/*
		* If lookup is racing with unlink return an error immediately.
		*/
		if (ip->i_d.di_mode == 0 && !(flags & XFS_IGET_CREATE)) {
		error = ENOENT;
		goto out_error;
		}

		/*
		* If IRECLAIMABLE is set, we've torn down the VFS inode already.
		* Need to carefully get it back into useable state.
		*/
		if (ip->i_flags & XFS_IRECLAIMABLE) {
		trace_xfs_iget_reclaim(ip);

		/*
		* We need to set XFS_IRECLAIM to prevent xfs_reclaim_inode
		* from stomping over us while we recycle the inode. We can't
		* clear the radix tree reclaimable tag yet as it requires
		* pag_ici_lock to be held exclusive.
		*/
		ip->i_flags \|= XFS_IRECLAIM;

		spin_unlock(&ip->i_flags_lock);
		rcu_read_unlock();

		error = -inode_init_always(mp->m_super, inode);
		if (error) {
		/*
		* Re-initializing the inode failed, and we are in deep
		* trouble. Try to re-add it to the reclaim list.
		*/
		rcu_read_lock();
		spin_lock(&ip->i_flags_lock);

		ip->i_flags &= ~(XFS_INEW \| XFS_IRECLAIM);
		ASSERT(ip->i_flags & XFS_IRECLAIMABLE);
		trace_xfs_iget_reclaim_fail(ip);
		goto out_error;
		}

		spin_lock(&pag->pag_ici_lock);
		spin_lock(&ip->i_flags_lock);

		/*
		* Clear the per-lifetime state in the inode as we are now
		* effectively a new inode and need to return to the initial
		* state before reuse occurs.
		*/
		ip->i_flags &= ~XFS_IRECLAIM_RESET_FLAGS;
		ip->i_flags \|= XFS_INEW;
		__xfs_inode_clear_reclaim_tag(mp, pag, ip);
		inode->i_state = I_NEW;

		ASSERT(!rwsem_is_locked(&ip->i_iolock.mr_lock));
		mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", ip->i_ino);

		spin_unlock(&ip->i_flags_lock);
		spin_unlock(&pag->pag_ici_lock);
		} else {
		/* If the VFS inode is being torn down, pause and try again. */
		if (!igrab(inode)) {
		trace_xfs_iget_skip(ip);
		error = EAGAIN;
		goto out_error;
		}

		/* We've got a live one. */
		spin_unlock(&ip->i_flags_lock);
		rcu_read_unlock();
		trace_xfs_iget_hit(ip);
		}

		if (lock_flags != 0)
		xfs_ilock(ip, lock_flags);

		xfs_iflags_clear(ip, XFS_ISTALE \| XFS_IDONTCACHE);
		XFS_STATS_INC(xs_ig_found);

		return 0;

		out_error:
		spin_unlock(&ip->i_flags_lock);
		rcu_read_unlock();
		return error;
		}


		static int
		xfs_iget_cache_miss(
		struct xfs_mount *mp,
		struct xfs_perag *pag,
		xfs_trans_t *tp,
		xfs_ino_t ino,
		struct xfs_inode **ipp,
		int flags,
		int lock_flags)
		{
		struct xfs_inode *ip;
		int error;
		xfs_agino_t agino = XFS_INO_TO_AGINO(mp, ino);
		int iflags;

		ip = xfs_inode_alloc(mp, ino);
		if (!ip)
		return ENOMEM;

		error = xfs_iread(mp, tp, ip, flags);
		if (error)
		goto out_destroy;

		trace_xfs_iget_miss(ip);

		if ((ip->i_d.di_mode == 0) && !(flags & XFS_IGET_CREATE)) {
		error = ENOENT;
		goto out_destroy;
		}

		/*
		* Preload the radix tree so we can insert safely under the
		* write spinlock. Note that we cannot sleep inside the preload
		* region. Since we can be called from transaction context, don't
		* recurse into the file system.
		*/
		if (radix_tree_preload(GFP_NOFS)) {
		error = EAGAIN;
		goto out_destroy;
		}

		/*
		* Because the inode hasn't been added to the radix-tree yet it can't
		* be found by another thread, so we can do the non-sleeping lock here.
		*/
		if (lock_flags) {
		if (!xfs_ilock_nowait(ip, lock_flags))
		BUG();
		}

		/*
		* These values must be set before inserting the inode into the radix
		* tree as the moment it is inserted a concurrent lookup (allowed by the
		* RCU locking mechanism) can find it and that lookup must see that this
		* is an inode currently under construction (i.e. that XFS_INEW is set).
		* The ip->i_flags_lock that protects the XFS_INEW flag forms the
		* memory barrier that ensures this detection works correctly at lookup
		* time.
		*/
		iflags = XFS_INEW;
		if (flags & XFS_IGET_DONTCACHE)
		iflags \|= XFS_IDONTCACHE;
		ip->i_udquot = ip->i_gdquot = NULL;
		xfs_iflags_set(ip, iflags);

		/* insert the new inode */
		spin_lock(&pag->pag_ici_lock);
		error = radix_tree_insert(&pag->pag_ici_root, agino, ip);
		if (unlikely(error)) {
		WARN_ON(error != -EEXIST);
		XFS_STATS_INC(xs_ig_dup);
		error = EAGAIN;
		goto out_preload_end;
		}
		spin_unlock(&pag->pag_ici_lock);
		radix_tree_preload_end();

		*ipp = ip;
		return 0;

		out_preload_end:
		spin_unlock(&pag->pag_ici_lock);
		radix_tree_preload_end();
		if (lock_flags)
		xfs_iunlock(ip, lock_flags);
		out_destroy:
		__destroy_inode(VFS_I(ip));
		xfs_inode_free(ip);
		return error;
		}

		/*
		* Look up an inode by number in the given file system.
		* The inode is looked up in the cache held in each AG.
		* If the inode is found in the cache, initialise the vfs inode
		* if necessary.
		*
		* If it is not in core, read it in from the file system's device,
		* add it to the cache and initialise the vfs inode.
		*
		* The inode is locked according to the value of the lock_flags parameter.
		* This flag parameter indicates how and if the inode's IO lock and inode lock
		* should be taken.
		*
		* mp -- the mount point structure for the current file system. It points
		* to the inode hash table.
		* tp -- a pointer to the current transaction if there is one. This is
		* simply passed through to the xfs_iread() call.
		* ino -- the number of the inode desired. This is the unique identifier
		* within the file system for the inode being requested.
		* lock_flags -- flags indicating how to lock the inode. See the comment
		* for xfs_ilock() for a list of valid values.
		*/
		int
		xfs_iget(
		xfs_mount_t *mp,
		xfs_trans_t *tp,
		xfs_ino_t ino,
		uint flags,
		uint lock_flags,
		xfs_inode_t **ipp)
		{
		xfs_inode_t *ip;
		int error;
		xfs_perag_t *pag;
		xfs_agino_t agino;

		/*
		* xfs_reclaim_inode() uses the ILOCK to ensure an inode
		* doesn't get freed while it's being referenced during a
		* radix tree traversal here. It assumes this function
		* aqcuires only the ILOCK (and therefore it has no need to
		* involve the IOLOCK in this synchronization).
		*/
		ASSERT((lock_flags & (XFS_IOLOCK_EXCL \| XFS_IOLOCK_SHARED)) == 0);

		/* reject inode numbers outside existing AGs */
		if (!ino \|\| XFS_INO_TO_AGNO(mp, ino) >= mp->m_sb.sb_agcount)
		return EINVAL;

		/* get the perag structure and ensure that it's inode capable */
		pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ino));
		agino = XFS_INO_TO_AGINO(mp, ino);

		again:
		error = 0;
		rcu_read_lock();
		ip = radix_tree_lookup(&pag->pag_ici_root, agino);

		if (ip) {
		error = xfs_iget_cache_hit(pag, ip, ino, flags, lock_flags);
		if (error)
		goto out_error_or_again;
		} else {
		rcu_read_unlock();
		XFS_STATS_INC(xs_ig_missed);

		error = xfs_iget_cache_miss(mp, pag, tp, ino, &ip,
		flags, lock_flags);
		if (error)
		goto out_error_or_again;
		}
		xfs_perag_put(pag);

		*ipp = ip;

		/*
		* If we have a real type for an on-disk inode, we can set ops(&unlock)
		* now. If it's a new inode being created, xfs_ialloc will handle it.
		*/
		if (xfs_iflags_test(ip, XFS_INEW) && ip->i_d.di_mode != 0)
		xfs_setup_inode(ip);
		return 0;

		out_error_or_again:
		if (error == EAGAIN) {
		delay(1);
		goto again;
		}
		xfs_perag_put(pag);
		return error;
		}