Merge tag 'for-3.11-rc1' of git://gitorious.org/linux-pwm/linux-pwm

[linux-2.6.git] / fs / xfs / xfs_vnodeops.c

/*
 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
 * Copyright (c) 2012 Red Hat, 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_bit.h"
#include "xfs_log.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir2.h"
#include "xfs_mount.h"
#include "xfs_da_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_inode_item.h"
#include "xfs_itable.h"
#include "xfs_ialloc.h"
#include "xfs_alloc.h"
#include "xfs_bmap.h"
#include "xfs_acl.h"
#include "xfs_attr.h"
#include "xfs_error.h"
#include "xfs_quota.h"
#include "xfs_utils.h"
#include "xfs_rtalloc.h"
#include "xfs_trans_space.h"
#include "xfs_log_priv.h"
#include "xfs_filestream.h"
#include "xfs_vnodeops.h"
#include "xfs_trace.h"
#include "xfs_icache.h"
#include "xfs_symlink.h"


/*
 * This is called by xfs_inactive to free any blocks beyond eof
 * when the link count isn't zero and by xfs_dm_punch_hole() when
 * punching a hole to EOF.
 */
int
xfs_free_eofblocks(
        xfs_mount_t     *mp,
        xfs_inode_t     *ip,
        bool            need_iolock)
{
        xfs_trans_t     *tp;
        int             error;
        xfs_fileoff_t   end_fsb;
        xfs_fileoff_t   last_fsb;
        xfs_filblks_t   map_len;
        int             nimaps;
        xfs_bmbt_irec_t imap;

        /*
         * Figure out if there are any blocks beyond the end
         * of the file.  If not, then there is nothing to do.
         */
        end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)XFS_ISIZE(ip));
        last_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
        if (last_fsb <= end_fsb)
                return 0;
        map_len = last_fsb - end_fsb;

        nimaps = 1;
        xfs_ilock(ip, XFS_ILOCK_SHARED);
        error = xfs_bmapi_read(ip, end_fsb, map_len, &imap, &nimaps, 0);
        xfs_iunlock(ip, XFS_ILOCK_SHARED);

        if (!error && (nimaps != 0) &&
            (imap.br_startblock != HOLESTARTBLOCK ||
             ip->i_delayed_blks)) {
                /*
                 * Attach the dquots to the inode up front.
                 */
                error = xfs_qm_dqattach(ip, 0);
                if (error)
                        return error;

                /*
                 * There are blocks after the end of file.
                 * Free them up now by truncating the file to
                 * its current size.
                 */
                tp = xfs_trans_alloc(mp, XFS_TRANS_INACTIVE);

                if (need_iolock) {
                        if (!xfs_ilock_nowait(ip, XFS_IOLOCK_EXCL)) {
                                xfs_trans_cancel(tp, 0);
                                return EAGAIN;
                        }
                }

                error = xfs_trans_reserve(tp, 0,
                                          XFS_ITRUNCATE_LOG_RES(mp),
                                          0, XFS_TRANS_PERM_LOG_RES,
                                          XFS_ITRUNCATE_LOG_COUNT);
                if (error) {
                        ASSERT(XFS_FORCED_SHUTDOWN(mp));
                        xfs_trans_cancel(tp, 0);
                        if (need_iolock)
                                xfs_iunlock(ip, XFS_IOLOCK_EXCL);
                        return error;
                }

                xfs_ilock(ip, XFS_ILOCK_EXCL);
                xfs_trans_ijoin(tp, ip, 0);

                /*
                 * Do not update the on-disk file size.  If we update the
                 * on-disk file size and then the system crashes before the
                 * contents of the file are flushed to disk then the files
                 * may be full of holes (ie NULL files bug).
                 */
                error = xfs_itruncate_extents(&tp, ip, XFS_DATA_FORK,
                                              XFS_ISIZE(ip));
                if (error) {
                        /*
                         * If we get an error at this point we simply don't
                         * bother truncating the file.
                         */
                        xfs_trans_cancel(tp,
                                         (XFS_TRANS_RELEASE_LOG_RES |
                                          XFS_TRANS_ABORT));
                } else {
                        error = xfs_trans_commit(tp,
                                                XFS_TRANS_RELEASE_LOG_RES);
                        if (!error)
                                xfs_inode_clear_eofblocks_tag(ip);
                }

                xfs_iunlock(ip, XFS_ILOCK_EXCL);
                if (need_iolock)
                        xfs_iunlock(ip, XFS_IOLOCK_EXCL);
        }
        return error;
}

int
xfs_release(
        xfs_inode_t     *ip)
{
        xfs_mount_t     *mp = ip->i_mount;
        int             error;

        if (!S_ISREG(ip->i_d.di_mode) || (ip->i_d.di_mode == 0))
                return 0;

        /* If this is a read-only mount, don't do this (would generate I/O) */
        if (mp->m_flags & XFS_MOUNT_RDONLY)
                return 0;

        if (!XFS_FORCED_SHUTDOWN(mp)) {
                int truncated;

                /*
                 * If we are using filestreams, and we have an unlinked
                 * file that we are processing the last close on, then nothing
                 * will be able to reopen and write to this file. Purge this
                 * inode from the filestreams cache so that it doesn't delay
                 * teardown of the inode.
                 */
                if ((ip->i_d.di_nlink == 0) && xfs_inode_is_filestream(ip))
                        xfs_filestream_deassociate(ip);

                /*
                 * If we previously truncated this file and removed old data
                 * in the process, we want to initiate "early" writeout on
                 * the last close.  This is an attempt to combat the notorious
                 * NULL files problem which is particularly noticeable from a
                 * truncate down, buffered (re-)write (delalloc), followed by
                 * a crash.  What we are effectively doing here is
                 * significantly reducing the time window where we'd otherwise
                 * be exposed to that problem.
                 */
                truncated = xfs_iflags_test_and_clear(ip, XFS_ITRUNCATED);
                if (truncated) {
                        xfs_iflags_clear(ip, XFS_IDIRTY_RELEASE);
                        if (VN_DIRTY(VFS_I(ip)) && ip->i_delayed_blks > 0) {
                                error = -filemap_flush(VFS_I(ip)->i_mapping);
                                if (error)
                                        return error;
                        }
                }
        }

        if (ip->i_d.di_nlink == 0)
                return 0;

        if (xfs_can_free_eofblocks(ip, false)) {

                /*
                 * If we can't get the iolock just skip truncating the blocks
                 * past EOF because we could deadlock with the mmap_sem
                 * otherwise.  We'll get another chance to drop them once the
                 * last reference to the inode is dropped, so we'll never leak
                 * blocks permanently.
                 *
                 * Further, check if the inode is being opened, written and
                 * closed frequently and we have delayed allocation blocks
                 * outstanding (e.g. streaming writes from the NFS server),
                 * truncating the blocks past EOF will cause fragmentation to
                 * occur.
                 *
                 * In this case don't do the truncation, either, but we have to
                 * be careful how we detect this case. Blocks beyond EOF show
                 * up as i_delayed_blks even when the inode is clean, so we
                 * need to truncate them away first before checking for a dirty
                 * release. Hence on the first dirty close we will still remove
                 * the speculative allocation, but after that we will leave it
                 * in place.
                 */
                if (xfs_iflags_test(ip, XFS_IDIRTY_RELEASE))
                        return 0;

                error = xfs_free_eofblocks(mp, ip, true);
                if (error && error != EAGAIN)
                        return error;

                /* delalloc blocks after truncation means it really is dirty */
                if (ip->i_delayed_blks)
                        xfs_iflags_set(ip, XFS_IDIRTY_RELEASE);
        }
        return 0;
}

/*
 * xfs_inactive
 *
 * This is called when the vnode reference count for the vnode
 * goes to zero.  If the file has been unlinked, then it must
 * now be truncated.  Also, we clear all of the read-ahead state
 * kept for the inode here since the file is now closed.
 */
int
xfs_inactive(
        xfs_inode_t     *ip)
{
        xfs_bmap_free_t free_list;
        xfs_fsblock_t   first_block;
        int             committed;
        xfs_trans_t     *tp;
        xfs_mount_t     *mp;
        int             error;
        int             truncate = 0;

        /*
         * If the inode is already free, then there can be nothing
         * to clean up here.
         */
        if (ip->i_d.di_mode == 0 || is_bad_inode(VFS_I(ip))) {
                ASSERT(ip->i_df.if_real_bytes == 0);
                ASSERT(ip->i_df.if_broot_bytes == 0);
                return VN_INACTIVE_CACHE;
        }

        mp = ip->i_mount;

        error = 0;

        /* If this is a read-only mount, don't do this (would generate I/O) */
        if (mp->m_flags & XFS_MOUNT_RDONLY)
                goto out;

        if (ip->i_d.di_nlink != 0) {
                /*
                 * force is true because we are evicting an inode from the
                 * cache. Post-eof blocks must be freed, lest we end up with
                 * broken free space accounting.
                 */
                if (xfs_can_free_eofblocks(ip, true)) {
                        error = xfs_free_eofblocks(mp, ip, false);
                        if (error)
                                return VN_INACTIVE_CACHE;
                }
                goto out;
        }

        if (S_ISREG(ip->i_d.di_mode) &&
            (ip->i_d.di_size != 0 || XFS_ISIZE(ip) != 0 ||
             ip->i_d.di_nextents > 0 || ip->i_delayed_blks > 0))
                truncate = 1;

        error = xfs_qm_dqattach(ip, 0);
        if (error)
                return VN_INACTIVE_CACHE;

        tp = xfs_trans_alloc(mp, XFS_TRANS_INACTIVE);
        error = xfs_trans_reserve(tp, 0,
                        (truncate || S_ISLNK(ip->i_d.di_mode)) ?
                                XFS_ITRUNCATE_LOG_RES(mp) :
                                XFS_IFREE_LOG_RES(mp),
                        0,
                        XFS_TRANS_PERM_LOG_RES,
                        XFS_ITRUNCATE_LOG_COUNT);
        if (error) {
                ASSERT(XFS_FORCED_SHUTDOWN(mp));
                xfs_trans_cancel(tp, 0);
                return VN_INACTIVE_CACHE;
        }

        xfs_ilock(ip, XFS_ILOCK_EXCL);
        xfs_trans_ijoin(tp, ip, 0);

        if (S_ISLNK(ip->i_d.di_mode)) {
                error = xfs_inactive_symlink(ip, &tp);
                if (error)
                        goto out_cancel;
        } else if (truncate) {
                ip->i_d.di_size = 0;
                xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);

                error = xfs_itruncate_extents(&tp, ip, XFS_DATA_FORK, 0);
                if (error)
                        goto out_cancel;

                ASSERT(ip->i_d.di_nextents == 0);
        }

        /*
         * If there are attributes associated with the file then blow them away
         * now.  The code calls a routine that recursively deconstructs the
         * attribute fork.  We need to just commit the current transaction
         * because we can't use it for xfs_attr_inactive().
         */
        if (ip->i_d.di_anextents > 0) {
                ASSERT(ip->i_d.di_forkoff != 0);

                error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
                if (error)
                        goto out_unlock;

                xfs_iunlock(ip, XFS_ILOCK_EXCL);

                error = xfs_attr_inactive(ip);
                if (error)
                        goto out;

                tp = xfs_trans_alloc(mp, XFS_TRANS_INACTIVE);
                error = xfs_trans_reserve(tp, 0,
                                          XFS_IFREE_LOG_RES(mp),
                                          0, XFS_TRANS_PERM_LOG_RES,
                                          XFS_INACTIVE_LOG_COUNT);
                if (error) {
                        xfs_trans_cancel(tp, 0);
                        goto out;
                }

                xfs_ilock(ip, XFS_ILOCK_EXCL);
                xfs_trans_ijoin(tp, ip, 0);
        }

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

        ASSERT(ip->i_d.di_anextents == 0);

        /*
         * Free the inode.
         */
        xfs_bmap_init(&free_list, &first_block);
        error = xfs_ifree(tp, ip, &free_list);
        if (error) {
                /*
                 * If we fail to free the inode, shut down.  The cancel
                 * might do that, we need to make sure.  Otherwise the
                 * inode might be lost for a long time or forever.
                 */
                if (!XFS_FORCED_SHUTDOWN(mp)) {
                        xfs_notice(mp, "%s: xfs_ifree returned error %d",
                                __func__, error);
                        xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
                }
                xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES|XFS_TRANS_ABORT);
        } else {
                /*
                 * Credit the quota account(s). The inode is gone.
                 */
                xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_ICOUNT, -1);

                /*
                 * Just ignore errors at this point.  There is nothing we can
                 * do except to try to keep going. Make sure it's not a silent
                 * error.
                 */
                error = xfs_bmap_finish(&tp,  &free_list, &committed);
                if (error)
                        xfs_notice(mp, "%s: xfs_bmap_finish returned error %d",
                                __func__, error);
                error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
                if (error)
                        xfs_notice(mp, "%s: xfs_trans_commit returned error %d",
                                __func__, error);
        }

        /*
         * Release the dquots held by inode, if any.
         */
        xfs_qm_dqdetach(ip);
out_unlock:
        xfs_iunlock(ip, XFS_ILOCK_EXCL);
out:
        return VN_INACTIVE_CACHE;
out_cancel:
        xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
        goto out_unlock;
}

/*
 * Lookups up an inode from "name". If ci_name is not NULL, then a CI match
 * is allowed, otherwise it has to be an exact match. If a CI match is found,
 * ci_name->name will point to a the actual name (caller must free) or
 * will be set to NULL if an exact match is found.
 */
int
xfs_lookup(
        xfs_inode_t             *dp,
        struct xfs_name         *name,
        xfs_inode_t             **ipp,
        struct xfs_name         *ci_name)
{
        xfs_ino_t               inum;
        int                     error;
        uint                    lock_mode;

        trace_xfs_lookup(dp, name);

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

        lock_mode = xfs_ilock_map_shared(dp);
        error = xfs_dir_lookup(NULL, dp, name, &inum, ci_name);
        xfs_iunlock_map_shared(dp, lock_mode);

        if (error)
                goto out;

        error = xfs_iget(dp->i_mount, NULL, inum, 0, 0, ipp);
        if (error)
                goto out_free_name;

        return 0;

out_free_name:
        if (ci_name)
                kmem_free(ci_name->name);
out:
        *ipp = NULL;
        return error;
}

int
xfs_create(
        xfs_inode_t             *dp,
        struct xfs_name         *name,
        umode_t                 mode,
        xfs_dev_t               rdev,
        xfs_inode_t             **ipp)
{
        int                     is_dir = S_ISDIR(mode);
        struct xfs_mount        *mp = dp->i_mount;
        struct xfs_inode        *ip = NULL;
        struct xfs_trans        *tp = NULL;
        int                     error;
        xfs_bmap_free_t         free_list;
        xfs_fsblock_t           first_block;
        bool                    unlock_dp_on_error = false;
        uint                    cancel_flags;
        int                     committed;
        prid_t                  prid;
        struct xfs_dquot        *udqp = NULL;
        struct xfs_dquot        *gdqp = NULL;
        uint                    resblks;
        uint                    log_res;
        uint                    log_count;

        trace_xfs_create(dp, name);

        if (XFS_FORCED_SHUTDOWN(mp))
                return XFS_ERROR(EIO);

        if (dp->i_d.di_flags & XFS_DIFLAG_PROJINHERIT)
                prid = xfs_get_projid(dp);
        else
                prid = XFS_PROJID_DEFAULT;

        /*
         * Make sure that we have allocated dquot(s) on disk.
         */
        error = xfs_qm_vop_dqalloc(dp, current_fsuid(), current_fsgid(), prid,
                        XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT, &udqp, &gdqp);
        if (error)
                return error;

        if (is_dir) {
                rdev = 0;
                resblks = XFS_MKDIR_SPACE_RES(mp, name->len);
                log_res = XFS_MKDIR_LOG_RES(mp);
                log_count = XFS_MKDIR_LOG_COUNT;
                tp = xfs_trans_alloc(mp, XFS_TRANS_MKDIR);
        } else {
                resblks = XFS_CREATE_SPACE_RES(mp, name->len);
                log_res = XFS_CREATE_LOG_RES(mp);
                log_count = XFS_CREATE_LOG_COUNT;
                tp = xfs_trans_alloc(mp, XFS_TRANS_CREATE);
        }

        cancel_flags = XFS_TRANS_RELEASE_LOG_RES;

        /*
         * Initially assume that the file does not exist and
         * reserve the resources for that case.  If that is not
         * the case we'll drop the one we have and get a more
         * appropriate transaction later.
         */
        error = xfs_trans_reserve(tp, resblks, log_res, 0,
                        XFS_TRANS_PERM_LOG_RES, log_count);
        if (error == ENOSPC) {
                /* flush outstanding delalloc blocks and retry */
                xfs_flush_inodes(mp);
                error = xfs_trans_reserve(tp, resblks, log_res, 0,
                                XFS_TRANS_PERM_LOG_RES, log_count);
        }
        if (error == ENOSPC) {
                /* No space at all so try a "no-allocation" reservation */
                resblks = 0;
                error = xfs_trans_reserve(tp, 0, log_res, 0,
                                XFS_TRANS_PERM_LOG_RES, log_count);
        }
        if (error) {
                cancel_flags = 0;
                goto out_trans_cancel;
        }

        xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
        unlock_dp_on_error = true;

        xfs_bmap_init(&free_list, &first_block);

        /*
         * Reserve disk quota and the inode.
         */
        error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp, resblks, 1, 0);
        if (error)
                goto out_trans_cancel;

        error = xfs_dir_canenter(tp, dp, name, resblks);
        if (error)
                goto out_trans_cancel;

        /*
         * A newly created regular or special file just has one directory
         * entry pointing to them, but a directory also the "." entry
         * pointing to itself.
         */
        error = xfs_dir_ialloc(&tp, dp, mode, is_dir ? 2 : 1, rdev,
                               prid, resblks > 0, &ip, &committed);
        if (error) {
                if (error == ENOSPC)
                        goto out_trans_cancel;
                goto out_trans_abort;
        }

        /*
         * Now we join the directory inode to the transaction.  We do not do it
         * earlier because xfs_dir_ialloc might commit the previous transaction
         * (and release all the locks).  An error from here on will result in
         * the transaction cancel unlocking dp so don't do it explicitly in the
         * error path.
         */
        xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
        unlock_dp_on_error = false;

        error = xfs_dir_createname(tp, dp, name, ip->i_ino,
                                        &first_block, &free_list, resblks ?
                                        resblks - XFS_IALLOC_SPACE_RES(mp) : 0);
        if (error) {
                ASSERT(error != ENOSPC);
                goto out_trans_abort;
        }
        xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
        xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);

        if (is_dir) {
                error = xfs_dir_init(tp, ip, dp);
                if (error)
                        goto out_bmap_cancel;

                error = xfs_bumplink(tp, dp);
                if (error)
                        goto out_bmap_cancel;
        }

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

        /*
         * Attach the dquot(s) to the inodes and modify them incore.
         * These ids of the inode couldn't have changed since the new
         * inode has been locked ever since it was created.
         */
        xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp);

        error = xfs_bmap_finish(&tp, &free_list, &committed);
        if (error)
                goto out_bmap_cancel;

        error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
        if (error)
                goto out_release_inode;

        xfs_qm_dqrele(udqp);
        xfs_qm_dqrele(gdqp);

        *ipp = ip;
        return 0;

 out_bmap_cancel:
        xfs_bmap_cancel(&free_list);
 out_trans_abort:
        cancel_flags |= XFS_TRANS_ABORT;
 out_trans_cancel:
        xfs_trans_cancel(tp, cancel_flags);
 out_release_inode:
        /*
         * Wait until after the current transaction is aborted to
         * release the inode.  This prevents recursive transactions
         * and deadlocks from xfs_inactive.
         */
        if (ip)
                IRELE(ip);

        xfs_qm_dqrele(udqp);
        xfs_qm_dqrele(gdqp);

        if (unlock_dp_on_error)
                xfs_iunlock(dp, XFS_ILOCK_EXCL);
        return error;
}

#ifdef DEBUG
int xfs_locked_n;
int xfs_small_retries;
int xfs_middle_retries;
int xfs_lots_retries;
int xfs_lock_delays;
#endif

/*
 * Bump the subclass so xfs_lock_inodes() acquires each lock with
 * a different value
 */
static inline int
xfs_lock_inumorder(int lock_mode, int subclass)
{
        if (lock_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL))
                lock_mode |= (subclass + XFS_LOCK_INUMORDER) << XFS_IOLOCK_SHIFT;
        if (lock_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL))
                lock_mode |= (subclass + XFS_LOCK_INUMORDER) << XFS_ILOCK_SHIFT;

        return lock_mode;
}

/*
 * The following routine will lock n inodes in exclusive mode.
 * We assume the caller calls us with the inodes in i_ino order.
 *
 * We need to detect deadlock where an inode that we lock
 * is in the AIL and we start waiting for another inode that is locked
 * by a thread in a long running transaction (such as truncate). This can
 * result in deadlock since the long running trans might need to wait
 * for the inode we just locked in order to push the tail and free space
 * in the log.
 */
void
xfs_lock_inodes(
        xfs_inode_t     **ips,
        int             inodes,
        uint            lock_mode)
{
        int             attempts = 0, i, j, try_lock;
        xfs_log_item_t  *lp;

        ASSERT(ips && (inodes >= 2)); /* we need at least two */

        try_lock = 0;
        i = 0;

again:
        for (; i < inodes; i++) {
                ASSERT(ips[i]);

                if (i && (ips[i] == ips[i-1]))  /* Already locked */
                        continue;

                /*
                 * If try_lock is not set yet, make sure all locked inodes
                 * are not in the AIL.
                 * If any are, set try_lock to be used later.
                 */

                if (!try_lock) {
                        for (j = (i - 1); j >= 0 && !try_lock; j--) {
                                lp = (xfs_log_item_t *)ips[j]->i_itemp;
                                if (lp && (lp->li_flags & XFS_LI_IN_AIL)) {
                                        try_lock++;
                                }
                        }
                }

                /*
                 * If any of the previous locks we have locked is in the AIL,
                 * we must TRY to get the second and subsequent locks. If
                 * we can't get any, we must release all we have
                 * and try again.
                 */

                if (try_lock) {
                        /* try_lock must be 0 if i is 0. */
                        /*
                         * try_lock means we have an inode locked
                         * that is in the AIL.
                         */
                        ASSERT(i != 0);
                        if (!xfs_ilock_nowait(ips[i], xfs_lock_inumorder(lock_mode, i))) {
                                attempts++;

                                /*
                                 * Unlock all previous guys and try again.
                                 * xfs_iunlock will try to push the tail
                                 * if the inode is in the AIL.
                                 */

                                for(j = i - 1; j >= 0; j--) {

                                        /*
                                         * Check to see if we've already
                                         * unlocked this one.
                                         * Not the first one going back,
                                         * and the inode ptr is the same.
                                         */
                                        if ((j != (i - 1)) && ips[j] ==
                                                                ips[j+1])
                                                continue;

                                        xfs_iunlock(ips[j], lock_mode);
                                }

                                if ((attempts % 5) == 0) {
                                        delay(1); /* Don't just spin the CPU */
#ifdef DEBUG
                                        xfs_lock_delays++;
#endif
                                }
                                i = 0;
                                try_lock = 0;
                                goto again;
                        }
                } else {
                        xfs_ilock(ips[i], xfs_lock_inumorder(lock_mode, i));
                }
        }

#ifdef DEBUG
        if (attempts) {
                if (attempts < 5) xfs_small_retries++;
                else if (attempts < 100) xfs_middle_retries++;
                else xfs_lots_retries++;
        } else {
                xfs_locked_n++;
        }
#endif
}

/*
 * xfs_lock_two_inodes() can only be used to lock one type of lock
 * at a time - the iolock or the ilock, but not both at once. If
 * we lock both at once, lockdep will report false positives saying
 * we have violated locking orders.
 */
void
xfs_lock_two_inodes(
        xfs_inode_t             *ip0,
        xfs_inode_t             *ip1,
        uint                    lock_mode)
{
        xfs_inode_t             *temp;
        int                     attempts = 0;
        xfs_log_item_t          *lp;

        if (lock_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL))
                ASSERT((lock_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)) == 0);
        ASSERT(ip0->i_ino != ip1->i_ino);

        if (ip0->i_ino > ip1->i_ino) {
                temp = ip0;
                ip0 = ip1;
                ip1 = temp;
        }

 again:
        xfs_ilock(ip0, xfs_lock_inumorder(lock_mode, 0));

        /*
         * If the first lock we have locked is in the AIL, we must TRY to get
         * the second lock. If we can't get it, we must release the first one
         * and try again.
         */
        lp = (xfs_log_item_t *)ip0->i_itemp;
        if (lp && (lp->li_flags & XFS_LI_IN_AIL)) {
                if (!xfs_ilock_nowait(ip1, xfs_lock_inumorder(lock_mode, 1))) {
                        xfs_iunlock(ip0, lock_mode);
                        if ((++attempts % 5) == 0)
                                delay(1); /* Don't just spin the CPU */
                        goto again;
                }
        } else {
                xfs_ilock(ip1, xfs_lock_inumorder(lock_mode, 1));
        }
}

int
xfs_remove(
        xfs_inode_t             *dp,
        struct xfs_name         *name,
        xfs_inode_t             *ip)
{
        xfs_mount_t             *mp = dp->i_mount;
        xfs_trans_t             *tp = NULL;
        int                     is_dir = S_ISDIR(ip->i_d.di_mode);
        int                     error = 0;
        xfs_bmap_free_t         free_list;
        xfs_fsblock_t           first_block;
        int                     cancel_flags;
        int                     committed;
        int                     link_zero;
        uint                    resblks;
        uint                    log_count;

        trace_xfs_remove(dp, name);

        if (XFS_FORCED_SHUTDOWN(mp))
                return XFS_ERROR(EIO);

        error = xfs_qm_dqattach(dp, 0);
        if (error)
                goto std_return;

        error = xfs_qm_dqattach(ip, 0);
        if (error)
                goto std_return;

        if (is_dir) {
                tp = xfs_trans_alloc(mp, XFS_TRANS_RMDIR);
                log_count = XFS_DEFAULT_LOG_COUNT;
        } else {
                tp = xfs_trans_alloc(mp, XFS_TRANS_REMOVE);
                log_count = XFS_REMOVE_LOG_COUNT;
        }
        cancel_flags = XFS_TRANS_RELEASE_LOG_RES;

        /*
         * We try to get the real space reservation first,
         * allowing for directory btree deletion(s) implying
         * possible bmap insert(s).  If we can't get the space
         * reservation then we use 0 instead, and avoid the bmap
         * btree insert(s) in the directory code by, if the bmap
         * insert tries to happen, instead trimming the LAST
         * block from the directory.
         */
        resblks = XFS_REMOVE_SPACE_RES(mp);
        error = xfs_trans_reserve(tp, resblks, XFS_REMOVE_LOG_RES(mp), 0,
                                  XFS_TRANS_PERM_LOG_RES, log_count);
        if (error == ENOSPC) {
                resblks = 0;
                error = xfs_trans_reserve(tp, 0, XFS_REMOVE_LOG_RES(mp), 0,
                                          XFS_TRANS_PERM_LOG_RES, log_count);
        }
        if (error) {
                ASSERT(error != ENOSPC);
                cancel_flags = 0;
                goto out_trans_cancel;
        }

        xfs_lock_two_inodes(dp, ip, XFS_ILOCK_EXCL);

        xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
        xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);

        /*
         * If we're removing a directory perform some additional validation.
         */
        if (is_dir) {
                ASSERT(ip->i_d.di_nlink >= 2);
                if (ip->i_d.di_nlink != 2) {
                        error = XFS_ERROR(ENOTEMPTY);
                        goto out_trans_cancel;
                }
                if (!xfs_dir_isempty(ip)) {
                        error = XFS_ERROR(ENOTEMPTY);
                        goto out_trans_cancel;
                }
        }

        xfs_bmap_init(&free_list, &first_block);
        error = xfs_dir_removename(tp, dp, name, ip->i_ino,
                                        &first_block, &free_list, resblks);
        if (error) {
                ASSERT(error != ENOENT);
                goto out_bmap_cancel;
        }
        xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);

        if (is_dir) {
                /*
                 * Drop the link from ip's "..".
                 */
                error = xfs_droplink(tp, dp);
                if (error)
                        goto out_bmap_cancel;

                /*
                 * Drop the "." link from ip to self.
                 */
                error = xfs_droplink(tp, ip);
                if (error)
                        goto out_bmap_cancel;
        } else {
                /*
                 * When removing a non-directory we need to log the parent
                 * inode here.  For a directory this is done implicitly
                 * by the xfs_droplink call for the ".." entry.
                 */
                xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
        }

        /*
         * Drop the link from dp to ip.
         */
        error = xfs_droplink(tp, ip);
        if (error)
                goto out_bmap_cancel;

        /*
         * Determine if this is the last link while
         * we are in the transaction.
         */
        link_zero = (ip->i_d.di_nlink == 0);

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

        error = xfs_bmap_finish(&tp, &free_list, &committed);
        if (error)
                goto out_bmap_cancel;

        error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
        if (error)
                goto std_return;

        /*
         * If we are using filestreams, kill the stream association.
         * If the file is still open it may get a new one but that
         * will get killed on last close in xfs_close() so we don't
         * have to worry about that.
         */
        if (!is_dir && link_zero && xfs_inode_is_filestream(ip))
                xfs_filestream_deassociate(ip);

        return 0;

 out_bmap_cancel:
        xfs_bmap_cancel(&free_list);
        cancel_flags |= XFS_TRANS_ABORT;
 out_trans_cancel:
        xfs_trans_cancel(tp, cancel_flags);
 std_return:
        return error;
}

int
xfs_link(
        xfs_inode_t             *tdp,
        xfs_inode_t             *sip,
        struct xfs_name         *target_name)
{
        xfs_mount_t             *mp = tdp->i_mount;
        xfs_trans_t             *tp;
        int                     error;
        xfs_bmap_free_t         free_list;
        xfs_fsblock_t           first_block;
        int                     cancel_flags;
        int                     committed;
        int                     resblks;

        trace_xfs_link(tdp, target_name);

        ASSERT(!S_ISDIR(sip->i_d.di_mode));

        if (XFS_FORCED_SHUTDOWN(mp))
                return XFS_ERROR(EIO);

        error = xfs_qm_dqattach(sip, 0);
        if (error)
                goto std_return;

        error = xfs_qm_dqattach(tdp, 0);
        if (error)
                goto std_return;

        tp = xfs_trans_alloc(mp, XFS_TRANS_LINK);
        cancel_flags = XFS_TRANS_RELEASE_LOG_RES;
        resblks = XFS_LINK_SPACE_RES(mp, target_name->len);
        error = xfs_trans_reserve(tp, resblks, XFS_LINK_LOG_RES(mp), 0,
                        XFS_TRANS_PERM_LOG_RES, XFS_LINK_LOG_COUNT);
        if (error == ENOSPC) {
                resblks = 0;
                error = xfs_trans_reserve(tp, 0, XFS_LINK_LOG_RES(mp), 0,
                                XFS_TRANS_PERM_LOG_RES, XFS_LINK_LOG_COUNT);
        }
        if (error) {
                cancel_flags = 0;
                goto error_return;
        }

        xfs_lock_two_inodes(sip, tdp, XFS_ILOCK_EXCL);

        xfs_trans_ijoin(tp, sip, XFS_ILOCK_EXCL);
        xfs_trans_ijoin(tp, tdp, XFS_ILOCK_EXCL);

        /*
         * If we are using project inheritance, we only allow hard link
         * creation in our tree when the project IDs are the same; else
         * the tree quota mechanism could be circumvented.
         */
        if (unlikely((tdp->i_d.di_flags & XFS_DIFLAG_PROJINHERIT) &&
                     (xfs_get_projid(tdp) != xfs_get_projid(sip)))) {
                error = XFS_ERROR(EXDEV);
                goto error_return;
        }

        error = xfs_dir_canenter(tp, tdp, target_name, resblks);
        if (error)
                goto error_return;

        xfs_bmap_init(&free_list, &first_block);

        error = xfs_dir_createname(tp, tdp, target_name, sip->i_ino,
                                        &first_block, &free_list, resblks);
        if (error)
                goto abort_return;
        xfs_trans_ichgtime(tp, tdp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
        xfs_trans_log_inode(tp, tdp, XFS_ILOG_CORE);

        error = xfs_bumplink(tp, sip);
        if (error)
                goto abort_return;

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

        error = xfs_bmap_finish (&tp, &free_list, &committed);
        if (error) {
                xfs_bmap_cancel(&free_list);
                goto abort_return;
        }

        return xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);

 abort_return:
        cancel_flags |= XFS_TRANS_ABORT;
 error_return:
        xfs_trans_cancel(tp, cancel_flags);
 std_return:
        return error;
}

int
xfs_set_dmattrs(
        xfs_inode_t     *ip,
        u_int           evmask,
        u_int16_t       state)
{
        xfs_mount_t     *mp = ip->i_mount;
        xfs_trans_t     *tp;
        int             error;

        if (!capable(CAP_SYS_ADMIN))
                return XFS_ERROR(EPERM);

        if (XFS_FORCED_SHUTDOWN(mp))
                return XFS_ERROR(EIO);

        tp = xfs_trans_alloc(mp, XFS_TRANS_SET_DMATTRS);
        error = xfs_trans_reserve(tp, 0, XFS_ICHANGE_LOG_RES (mp), 0, 0, 0);
        if (error) {
                xfs_trans_cancel(tp, 0);
                return error;
        }
        xfs_ilock(ip, XFS_ILOCK_EXCL);
        xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);

        ip->i_d.di_dmevmask = evmask;
        ip->i_d.di_dmstate  = state;

        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
        error = xfs_trans_commit(tp, 0);

        return error;
}

/*
 * xfs_alloc_file_space()
 *      This routine allocates disk space for the given file.
 *
 *      If alloc_type == 0, this request is for an ALLOCSP type
 *      request which will change the file size.  In this case, no
 *      DMAPI event will be generated by the call.  A TRUNCATE event
 *      will be generated later by xfs_setattr.
 *
 *      If alloc_type != 0, this request is for a RESVSP type
 *      request, and a DMAPI DM_EVENT_WRITE will be generated if the
 *      lower block boundary byte address is less than the file's
 *      length.
 *
 * RETURNS:
 *       0 on success
 *      errno on error
 *
 */
STATIC int
xfs_alloc_file_space(
        xfs_inode_t             *ip,
        xfs_off_t               offset,
        xfs_off_t               len,
        int                     alloc_type,
        int                     attr_flags)
{
        xfs_mount_t             *mp = ip->i_mount;
        xfs_off_t               count;
        xfs_filblks_t           allocated_fsb;
        xfs_filblks_t           allocatesize_fsb;
        xfs_extlen_t            extsz, temp;
        xfs_fileoff_t           startoffset_fsb;
        xfs_fsblock_t           firstfsb;
        int                     nimaps;
        int                     quota_flag;
        int                     rt;
        xfs_trans_t             *tp;
        xfs_bmbt_irec_t         imaps[1], *imapp;
        xfs_bmap_free_t         free_list;
        uint                    qblocks, resblks, resrtextents;
        int                     committed;
        int                     error;

        trace_xfs_alloc_file_space(ip);

        if (XFS_FORCED_SHUTDOWN(mp))
                return XFS_ERROR(EIO);

        error = xfs_qm_dqattach(ip, 0);
        if (error)
                return error;

        if (len <= 0)
                return XFS_ERROR(EINVAL);

        rt = XFS_IS_REALTIME_INODE(ip);
        extsz = xfs_get_extsz_hint(ip);

        count = len;
        imapp = &imaps[0];
        nimaps = 1;
        startoffset_fsb = XFS_B_TO_FSBT(mp, offset);
        allocatesize_fsb = XFS_B_TO_FSB(mp, count);

        /*
         * Allocate file space until done or until there is an error
         */
        while (allocatesize_fsb && !error) {
                xfs_fileoff_t   s, e;

                /*
                 * Determine space reservations for data/realtime.
                 */
                if (unlikely(extsz)) {
                        s = startoffset_fsb;
                        do_div(s, extsz);
                        s *= extsz;
                        e = startoffset_fsb + allocatesize_fsb;
                        if ((temp = do_mod(startoffset_fsb, extsz)))
                                e += temp;
                        if ((temp = do_mod(e, extsz)))
                                e += extsz - temp;
                } else {
                        s = 0;
                        e = allocatesize_fsb;
                }

                /*
                 * The transaction reservation is limited to a 32-bit block
                 * count, hence we need to limit the number of blocks we are
                 * trying to reserve to avoid an overflow. We can't allocate
                 * more than @nimaps extents, and an extent is limited on disk
                 * to MAXEXTLEN (21 bits), so use that to enforce the limit.
                 */
                resblks = min_t(xfs_fileoff_t, (e - s), (MAXEXTLEN * nimaps));
                if (unlikely(rt)) {
                        resrtextents = qblocks = resblks;
                        resrtextents /= mp->m_sb.sb_rextsize;
                        resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
                        quota_flag = XFS_QMOPT_RES_RTBLKS;
                } else {
                        resrtextents = 0;
                        resblks = qblocks = XFS_DIOSTRAT_SPACE_RES(mp, resblks);
                        quota_flag = XFS_QMOPT_RES_REGBLKS;
                }

                /*
                 * Allocate and setup the transaction.
                 */
                tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
                error = xfs_trans_reserve(tp, resblks,
                                          XFS_WRITE_LOG_RES(mp), resrtextents,
                                          XFS_TRANS_PERM_LOG_RES,
                                          XFS_WRITE_LOG_COUNT);
                /*
                 * Check for running out of space
                 */
                if (error) {
                        /*
                         * Free the transaction structure.
                         */
                        ASSERT(error == ENOSPC || XFS_FORCED_SHUTDOWN(mp));
                        xfs_trans_cancel(tp, 0);
                        break;
                }
                xfs_ilock(ip, XFS_ILOCK_EXCL);
                error = xfs_trans_reserve_quota_nblks(tp, ip, qblocks,
                                                      0, quota_flag);
                if (error)
                        goto error1;

                xfs_trans_ijoin(tp, ip, 0);

                xfs_bmap_init(&free_list, &firstfsb);
                error = xfs_bmapi_write(tp, ip, startoffset_fsb,
                                        allocatesize_fsb, alloc_type, &firstfsb,
                                        0, imapp, &nimaps, &free_list);
                if (error) {
                        goto error0;
                }

                /*
                 * Complete the transaction
                 */
                error = xfs_bmap_finish(&tp, &free_list, &committed);
                if (error) {
                        goto error0;
                }

                error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
                xfs_iunlock(ip, XFS_ILOCK_EXCL);
                if (error) {
                        break;
                }

                allocated_fsb = imapp->br_blockcount;

                if (nimaps == 0) {
                        error = XFS_ERROR(ENOSPC);
                        break;
                }

                startoffset_fsb += allocated_fsb;
                allocatesize_fsb -= allocated_fsb;
        }

        return error;

error0: /* Cancel bmap, unlock inode, unreserve quota blocks, cancel trans */
        xfs_bmap_cancel(&free_list);
        xfs_trans_unreserve_quota_nblks(tp, ip, (long)qblocks, 0, quota_flag);

error1: /* Just cancel transaction */
        xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
        xfs_iunlock(ip, XFS_ILOCK_EXCL);
        return error;
}

/*
 * Zero file bytes between startoff and endoff inclusive.
 * The iolock is held exclusive and no blocks are buffered.
 *
 * This function is used by xfs_free_file_space() to zero
 * partial blocks when the range to free is not block aligned.
 * When unreserving space with boundaries that are not block
 * aligned we round up the start and round down the end
 * boundaries and then use this function to zero the parts of
 * the blocks that got dropped during the rounding.
 */
STATIC int
xfs_zero_remaining_bytes(
        xfs_inode_t             *ip,
        xfs_off_t               startoff,
        xfs_off_t               endoff)
{
        xfs_bmbt_irec_t         imap;
        xfs_fileoff_t           offset_fsb;
        xfs_off_t               lastoffset;
        xfs_off_t               offset;
        xfs_buf_t               *bp;
        xfs_mount_t             *mp = ip->i_mount;
        int                     nimap;
        int                     error = 0;

        /*
         * Avoid doing I/O beyond eof - it's not necessary
         * since nothing can read beyond eof.  The space will
         * be zeroed when the file is extended anyway.
         */
        if (startoff >= XFS_ISIZE(ip))
                return 0;

        if (endoff > XFS_ISIZE(ip))
                endoff = XFS_ISIZE(ip);

        bp = xfs_buf_get_uncached(XFS_IS_REALTIME_INODE(ip) ?
                                        mp->m_rtdev_targp : mp->m_ddev_targp,
                                  BTOBB(mp->m_sb.sb_blocksize), 0);
        if (!bp)
                return XFS_ERROR(ENOMEM);

        xfs_buf_unlock(bp);

        for (offset = startoff; offset <= endoff; offset = lastoffset + 1) {
                offset_fsb = XFS_B_TO_FSBT(mp, offset);
                nimap = 1;
                error = xfs_bmapi_read(ip, offset_fsb, 1, &imap, &nimap, 0);
                if (error || nimap < 1)
                        break;
                ASSERT(imap.br_blockcount >= 1);
                ASSERT(imap.br_startoff == offset_fsb);
                lastoffset = XFS_FSB_TO_B(mp, imap.br_startoff + 1) - 1;
                if (lastoffset > endoff)
                        lastoffset = endoff;
                if (imap.br_startblock == HOLESTARTBLOCK)
                        continue;
                ASSERT(imap.br_startblock != DELAYSTARTBLOCK);
                if (imap.br_state == XFS_EXT_UNWRITTEN)
                        continue;
                XFS_BUF_UNDONE(bp);
                XFS_BUF_UNWRITE(bp);
                XFS_BUF_READ(bp);
                XFS_BUF_SET_ADDR(bp, xfs_fsb_to_db(ip, imap.br_startblock));
                xfsbdstrat(mp, bp);
                error = xfs_buf_iowait(bp);
                if (error) {
                        xfs_buf_ioerror_alert(bp,
                                        "xfs_zero_remaining_bytes(read)");
                        break;
                }
                memset(bp->b_addr +
                        (offset - XFS_FSB_TO_B(mp, imap.br_startoff)),
                      0, lastoffset - offset + 1);
                XFS_BUF_UNDONE(bp);
                XFS_BUF_UNREAD(bp);
                XFS_BUF_WRITE(bp);
                xfsbdstrat(mp, bp);
                error = xfs_buf_iowait(bp);
                if (error) {
                        xfs_buf_ioerror_alert(bp,
                                        "xfs_zero_remaining_bytes(write)");
                        break;
                }
        }
        xfs_buf_free(bp);
        return error;
}

/*
 * xfs_free_file_space()
 *      This routine frees disk space for the given file.
 *
 *      This routine is only called by xfs_change_file_space
 *      for an UNRESVSP type call.
 *
 * RETURNS:
 *       0 on success
 *      errno on error
 *
 */
STATIC int
xfs_free_file_space(
        xfs_inode_t             *ip,
        xfs_off_t               offset,
        xfs_off_t               len,
        int                     attr_flags)
{
        int                     committed;
        int                     done;
        xfs_fileoff_t           endoffset_fsb;
        int                     error;
        xfs_fsblock_t           firstfsb;
        xfs_bmap_free_t         free_list;
        xfs_bmbt_irec_t         imap;
        xfs_off_t               ioffset;
        xfs_extlen_t            mod=0;
        xfs_mount_t             *mp;
        int                     nimap;
        uint                    resblks;
        xfs_off_t               rounding;
        int                     rt;
        xfs_fileoff_t           startoffset_fsb;
        xfs_trans_t             *tp;
        int                     need_iolock = 1;

        mp = ip->i_mount;

        trace_xfs_free_file_space(ip);

        error = xfs_qm_dqattach(ip, 0);
        if (error)
                return error;

        error = 0;
        if (len <= 0)   /* if nothing being freed */
                return error;
        rt = XFS_IS_REALTIME_INODE(ip);
        startoffset_fsb = XFS_B_TO_FSB(mp, offset);
        endoffset_fsb = XFS_B_TO_FSBT(mp, offset + len);

        if (attr_flags & XFS_ATTR_NOLOCK)
                need_iolock = 0;
        if (need_iolock) {
                xfs_ilock(ip, XFS_IOLOCK_EXCL);
                /* wait for the completion of any pending DIOs */
                inode_dio_wait(VFS_I(ip));
        }

        rounding = max_t(xfs_off_t, 1 << mp->m_sb.sb_blocklog, PAGE_CACHE_SIZE);
        ioffset = offset & ~(rounding - 1);
        error = -filemap_write_and_wait_range(VFS_I(ip)->i_mapping,
                                              ioffset, -1);
        if (error)
                goto out_unlock_iolock;
        truncate_pagecache_range(VFS_I(ip), ioffset, -1);

        /*
         * Need to zero the stuff we're not freeing, on disk.
         * If it's a realtime file & can't use unwritten extents then we
         * actually need to zero the extent edges.  Otherwise xfs_bunmapi
         * will take care of it for us.
         */
        if (rt && !xfs_sb_version_hasextflgbit(&mp->m_sb)) {
                nimap = 1;
                error = xfs_bmapi_read(ip, startoffset_fsb, 1,
                                        &imap, &nimap, 0);
                if (error)
                        goto out_unlock_iolock;
                ASSERT(nimap == 0 || nimap == 1);
                if (nimap && imap.br_startblock != HOLESTARTBLOCK) {
                        xfs_daddr_t     block;

                        ASSERT(imap.br_startblock != DELAYSTARTBLOCK);
                        block = imap.br_startblock;
                        mod = do_div(block, mp->m_sb.sb_rextsize);
                        if (mod)
                                startoffset_fsb += mp->m_sb.sb_rextsize - mod;
                }
                nimap = 1;
                error = xfs_bmapi_read(ip, endoffset_fsb - 1, 1,
                                        &imap, &nimap, 0);
                if (error)
                        goto out_unlock_iolock;
                ASSERT(nimap == 0 || nimap == 1);
                if (nimap && imap.br_startblock != HOLESTARTBLOCK) {
                        ASSERT(imap.br_startblock != DELAYSTARTBLOCK);
                        mod++;
                        if (mod && (mod != mp->m_sb.sb_rextsize))
                                endoffset_fsb -= mod;
                }
        }
        if ((done = (endoffset_fsb <= startoffset_fsb)))
                /*
                 * One contiguous piece to clear
                 */
                error = xfs_zero_remaining_bytes(ip, offset, offset + len - 1);
        else {
                /*
                 * Some full blocks, possibly two pieces to clear
                 */
                if (offset < XFS_FSB_TO_B(mp, startoffset_fsb))
                        error = xfs_zero_remaining_bytes(ip, offset,
                                XFS_FSB_TO_B(mp, startoffset_fsb) - 1);
                if (!error &&
                    XFS_FSB_TO_B(mp, endoffset_fsb) < offset + len)
                        error = xfs_zero_remaining_bytes(ip,
                                XFS_FSB_TO_B(mp, endoffset_fsb),
                                offset + len - 1);
        }

        /*
         * free file space until done or until there is an error
         */
        resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
        while (!error && !done) {

                /*
                 * allocate and setup the transaction. Allow this
                 * transaction to dip into the reserve blocks to ensure
                 * the freeing of the space succeeds at ENOSPC.
                 */
                tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
                tp->t_flags |= XFS_TRANS_RESERVE;
                error = xfs_trans_reserve(tp,
                                          resblks,
                                          XFS_WRITE_LOG_RES(mp),
                                          0,
                                          XFS_TRANS_PERM_LOG_RES,
                                          XFS_WRITE_LOG_COUNT);

                /*
                 * check for running out of space
                 */
                if (error) {
                        /*
                         * Free the transaction structure.
                         */
                        ASSERT(error == ENOSPC || XFS_FORCED_SHUTDOWN(mp));
                        xfs_trans_cancel(tp, 0);
                        break;
                }
                xfs_ilock(ip, XFS_ILOCK_EXCL);
                error = xfs_trans_reserve_quota(tp, mp,
                                ip->i_udquot, ip->i_gdquot,
                                resblks, 0, XFS_QMOPT_RES_REGBLKS);
                if (error)
                        goto error1;

                xfs_trans_ijoin(tp, ip, 0);

                /*
                 * issue the bunmapi() call to free the blocks
                 */
                xfs_bmap_init(&free_list, &firstfsb);
                error = xfs_bunmapi(tp, ip, startoffset_fsb,
                                  endoffset_fsb - startoffset_fsb,
                                  0, 2, &firstfsb, &free_list, &done);
                if (error) {
                        goto error0;
                }

                /*
                 * complete the transaction
                 */
                error = xfs_bmap_finish(&tp, &free_list, &committed);
                if (error) {
                        goto error0;
                }

                error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
                xfs_iunlock(ip, XFS_ILOCK_EXCL);
        }

 out_unlock_iolock:
        if (need_iolock)
                xfs_iunlock(ip, XFS_IOLOCK_EXCL);
        return error;

 error0:
        xfs_bmap_cancel(&free_list);
 error1:
        xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
        xfs_iunlock(ip, need_iolock ? (XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL) :
                    XFS_ILOCK_EXCL);
        return error;
}


STATIC int
xfs_zero_file_space(
        struct xfs_inode        *ip,
        xfs_off_t               offset,
        xfs_off_t               len,
        int                     attr_flags)
{
        struct xfs_mount        *mp = ip->i_mount;
        uint                    granularity;
        xfs_off_t               start_boundary;
        xfs_off_t               end_boundary;
        int                     error;

        granularity = max_t(uint, 1 << mp->m_sb.sb_blocklog, PAGE_CACHE_SIZE);

        /*
         * Round the range of extents we are going to convert inwards.  If the
         * offset is aligned, then it doesn't get changed so we zero from the
         * start of the block offset points to.
         */
        start_boundary = round_up(offset, granularity);
        end_boundary = round_down(offset + len, granularity);

        ASSERT(start_boundary >= offset);
        ASSERT(end_boundary <= offset + len);

        if (!(attr_flags & XFS_ATTR_NOLOCK))
                xfs_ilock(ip, XFS_IOLOCK_EXCL);

        if (start_boundary < end_boundary - 1) {
                /* punch out the page cache over the conversion range */
                truncate_pagecache_range(VFS_I(ip), start_boundary,
                                         end_boundary - 1);
                /* convert the blocks */
                error = xfs_alloc_file_space(ip, start_boundary,
                                        end_boundary - start_boundary - 1,
                                        XFS_BMAPI_PREALLOC | XFS_BMAPI_CONVERT,
                                        attr_flags);
                if (error)
                        goto out_unlock;

                /* We've handled the interior of the range, now for the edges */
                if (start_boundary != offset)
                        error = xfs_iozero(ip, offset, start_boundary - offset);
                if (error)
                        goto out_unlock;

                if (end_boundary != offset + len)
                        error = xfs_iozero(ip, end_boundary,
                                           offset + len - end_boundary);

        } else {
                /*
                 * It's either a sub-granularity range or the range spanned lies
                 * partially across two adjacent blocks.
                 */
                error = xfs_iozero(ip, offset, len);
        }

out_unlock:
        if (!(attr_flags & XFS_ATTR_NOLOCK))
                xfs_iunlock(ip, XFS_IOLOCK_EXCL);
        return error;

}

/*
 * xfs_change_file_space()
 *      This routine allocates or frees disk space for the given file.
 *      The user specified parameters are checked for alignment and size
 *      limitations.
 *
 * RETURNS:
 *       0 on success
 *      errno on error
 *
 */
int
xfs_change_file_space(
        xfs_inode_t     *ip,
        int             cmd,
        xfs_flock64_t   *bf,
        xfs_off_t       offset,
        int             attr_flags)
{
        xfs_mount_t     *mp = ip->i_mount;
        int             clrprealloc;
        int             error;
        xfs_fsize_t     fsize;
        int             setprealloc;
        xfs_off_t       startoffset;
        xfs_trans_t     *tp;
        struct iattr    iattr;

        if (!S_ISREG(ip->i_d.di_mode))
                return XFS_ERROR(EINVAL);

        switch (bf->l_whence) {
        case 0: /*SEEK_SET*/
                break;
        case 1: /*SEEK_CUR*/
                bf->l_start += offset;
                break;
        case 2: /*SEEK_END*/
                bf->l_start += XFS_ISIZE(ip);
                break;
        default:
                return XFS_ERROR(EINVAL);
        }

        /*
         * length of <= 0 for resv/unresv/zero is invalid.  length for
         * alloc/free is ignored completely and we have no idea what userspace
         * might have set it to, so set it to zero to allow range
         * checks to pass.
         */
        switch (cmd) {
        case XFS_IOC_ZERO_RANGE:
        case XFS_IOC_RESVSP:
        case XFS_IOC_RESVSP64:
        case XFS_IOC_UNRESVSP:
        case XFS_IOC_UNRESVSP64:
                if (bf->l_len <= 0)
                        return XFS_ERROR(EINVAL);
                break;
        default:
                bf->l_len = 0;
                break;
        }

        if (bf->l_start < 0 ||
            bf->l_start > mp->m_super->s_maxbytes ||
            bf->l_start + bf->l_len < 0 ||
            bf->l_start + bf->l_len >= mp->m_super->s_maxbytes)
                return XFS_ERROR(EINVAL);

        bf->l_whence = 0;

        startoffset = bf->l_start;
        fsize = XFS_ISIZE(ip);

        setprealloc = clrprealloc = 0;
        switch (cmd) {
        case XFS_IOC_ZERO_RANGE:
                error = xfs_zero_file_space(ip, startoffset, bf->l_len,
                                                attr_flags);
                if (error)
                        return error;
                setprealloc = 1;
                break;

        case XFS_IOC_RESVSP:
        case XFS_IOC_RESVSP64:
                error = xfs_alloc_file_space(ip, startoffset, bf->l_len,
                                                XFS_BMAPI_PREALLOC, attr_flags);
                if (error)
                        return error;
                setprealloc = 1;
                break;

        case XFS_IOC_UNRESVSP:
        case XFS_IOC_UNRESVSP64:
                if ((error = xfs_free_file_space(ip, startoffset, bf->l_len,
                                                                attr_flags)))
                        return error;
                break;

        case XFS_IOC_ALLOCSP:
        case XFS_IOC_ALLOCSP64:
        case XFS_IOC_FREESP:
        case XFS_IOC_FREESP64:
                /*
                 * These operations actually do IO when extending the file, but
                 * the allocation is done seperately to the zeroing that is
                 * done. This set of operations need to be serialised against
                 * other IO operations, such as truncate and buffered IO. We
                 * need to take the IOLOCK here to serialise the allocation and
                 * zeroing IO to prevent other IOLOCK holders (e.g. getbmap,
                 * truncate, direct IO) from racing against the transient
                 * allocated but not written state we can have here.
                 */
                xfs_ilock(ip, XFS_IOLOCK_EXCL);
                if (startoffset > fsize) {
                        error = xfs_alloc_file_space(ip, fsize,
                                        startoffset - fsize, 0,
                                        attr_flags | XFS_ATTR_NOLOCK);
                        if (error) {
                                xfs_iunlock(ip, XFS_IOLOCK_EXCL);
                                break;
                        }
                }

                iattr.ia_valid = ATTR_SIZE;
                iattr.ia_size = startoffset;

                error = xfs_setattr_size(ip, &iattr,
                                         attr_flags | XFS_ATTR_NOLOCK);
                xfs_iunlock(ip, XFS_IOLOCK_EXCL);

                if (error)
                        return error;

                clrprealloc = 1;
                break;

        default:
                ASSERT(0);
                return XFS_ERROR(EINVAL);
        }

        /*
         * update the inode timestamp, mode, and prealloc flag bits
         */
        tp = xfs_trans_alloc(mp, XFS_TRANS_WRITEID);

        if ((error = xfs_trans_reserve(tp, 0, XFS_WRITEID_LOG_RES(mp),
                                      0, 0, 0))) {
                /* ASSERT(0); */
                xfs_trans_cancel(tp, 0);
                return error;
        }

        xfs_ilock(ip, XFS_ILOCK_EXCL);
        xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);

        if ((attr_flags & XFS_ATTR_DMI) == 0) {
                ip->i_d.di_mode &= ~S_ISUID;

                /*
                 * Note that we don't have to worry about mandatory
                 * file locking being disabled here because we only
                 * clear the S_ISGID bit if the Group execute bit is
                 * on, but if it was on then mandatory locking wouldn't
                 * have been enabled.
                 */
                if (ip->i_d.di_mode & S_IXGRP)
                        ip->i_d.di_mode &= ~S_ISGID;

                xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
        }
        if (setprealloc)
                ip->i_d.di_flags |= XFS_DIFLAG_PREALLOC;
        else if (clrprealloc)
                ip->i_d.di_flags &= ~XFS_DIFLAG_PREALLOC;

        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
        if (attr_flags & XFS_ATTR_SYNC)
                xfs_trans_set_sync(tp);
        return xfs_trans_commit(tp, 0);
}