Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/avi/kvm

[wrt350n-kernel.git] / fs / xfs / xfs_rename.c

/*
 * Copyright (c) 2000-2003,2005 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_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_dir2.h"
#include "xfs_dmapi.h"
#include "xfs_mount.h"
#include "xfs_da_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_dir2_sf.h"
#include "xfs_attr_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_inode_item.h"
#include "xfs_bmap.h"
#include "xfs_error.h"
#include "xfs_quota.h"
#include "xfs_refcache.h"
#include "xfs_utils.h"
#include "xfs_trans_space.h"


/*
 * Given an array of up to 4 inode pointers, unlock the pointed to inodes.
 * If there are fewer than 4 entries in the array, the empty entries will
 * be at the end and will have NULL pointers in them.
 */
STATIC void
xfs_rename_unlock4(
        xfs_inode_t     **i_tab,
        uint            lock_mode)
{
        int     i;

        xfs_iunlock(i_tab[0], lock_mode);
        for (i = 1; i < 4; i++) {
                if (i_tab[i] == NULL) {
                        break;
                }
                /*
                 * Watch out for duplicate entries in the table.
                 */
                if (i_tab[i] != i_tab[i-1]) {
                        xfs_iunlock(i_tab[i], lock_mode);
                }
        }
}

#ifdef DEBUG
int xfs_rename_skip, xfs_rename_nskip;
#endif

/*
 * The following routine will acquire the locks required for a rename
 * operation. The code understands the semantics of renames and will
 * validate that name1 exists under dp1 & that name2 may or may not
 * exist under dp2.
 *
 * We are renaming dp1/name1 to dp2/name2.
 *
 * Return ENOENT if dp1 does not exist, other lookup errors, or 0 for success.
 */
STATIC int
xfs_lock_for_rename(
        xfs_inode_t     *dp1,   /* old (source) directory inode */
        xfs_inode_t     *dp2,   /* new (target) directory inode */
        bhv_vname_t     *vname1,/* old entry name */
        bhv_vname_t     *vname2,/* new entry name */
        xfs_inode_t     **ipp1, /* inode of old entry */
        xfs_inode_t     **ipp2, /* inode of new entry, if it
                                   already exists, NULL otherwise. */
        xfs_inode_t     **i_tab,/* array of inode returned, sorted */
        int             *num_inodes)  /* number of inodes in array */
{
        xfs_inode_t             *ip1, *ip2, *temp;
        xfs_ino_t               inum1, inum2;
        int                     error;
        int                     i, j;
        uint                    lock_mode;
        int                     diff_dirs = (dp1 != dp2);

        ip2 = NULL;

        /*
         * First, find out the current inums of the entries so that we
         * can determine the initial locking order.  We'll have to
         * sanity check stuff after all the locks have been acquired
         * to see if we still have the right inodes, directories, etc.
         */
        lock_mode = xfs_ilock_map_shared(dp1);
        error = xfs_get_dir_entry(vname1, &ip1);
        if (error) {
                xfs_iunlock_map_shared(dp1, lock_mode);
                return error;
        }

        inum1 = ip1->i_ino;

        ASSERT(ip1);
        ITRACE(ip1);

        /*
         * Unlock dp1 and lock dp2 if they are different.
         */

        if (diff_dirs) {
                xfs_iunlock_map_shared(dp1, lock_mode);
                lock_mode = xfs_ilock_map_shared(dp2);
        }

        error = xfs_dir_lookup_int(XFS_ITOBHV(dp2), lock_mode,
                                   vname2, &inum2, &ip2);
        if (error == ENOENT) {          /* target does not need to exist. */
                inum2 = 0;
        } else if (error) {
                /*
                 * If dp2 and dp1 are the same, the next line unlocks dp1.
                 * Got it?
                 */
                xfs_iunlock_map_shared(dp2, lock_mode);
                IRELE (ip1);
                return error;
        } else {
                ITRACE(ip2);
        }

        /*
         * i_tab contains a list of pointers to inodes.  We initialize
         * the table here & we'll sort it.  We will then use it to
         * order the acquisition of the inode locks.
         *
         * Note that the table may contain duplicates.  e.g., dp1 == dp2.
         */
        i_tab[0] = dp1;
        i_tab[1] = dp2;
        i_tab[2] = ip1;
        if (inum2 == 0) {
                *num_inodes = 3;
                i_tab[3] = NULL;
        } else {
                *num_inodes = 4;
                i_tab[3] = ip2;
        }

        /*
         * Sort the elements via bubble sort.  (Remember, there are at
         * most 4 elements to sort, so this is adequate.)
         */
        for (i=0; i < *num_inodes; i++) {
                for (j=1; j < *num_inodes; j++) {
                        if (i_tab[j]->i_ino < i_tab[j-1]->i_ino) {
                                temp = i_tab[j];
                                i_tab[j] = i_tab[j-1];
                                i_tab[j-1] = temp;
                        }
                }
        }

        /*
         * We have dp2 locked. If it isn't first, unlock it.
         * If it is first, tell xfs_lock_inodes so it can skip it
         * when locking. if dp1 == dp2, xfs_lock_inodes will skip both
         * since they are equal. xfs_lock_inodes needs all these inodes
         * so that it can unlock and retry if there might be a dead-lock
         * potential with the log.
         */

        if (i_tab[0] == dp2 && lock_mode == XFS_ILOCK_SHARED) {
#ifdef DEBUG
                xfs_rename_skip++;
#endif
                xfs_lock_inodes(i_tab, *num_inodes, 1, XFS_ILOCK_SHARED);
        } else {
#ifdef DEBUG
                xfs_rename_nskip++;
#endif
                xfs_iunlock_map_shared(dp2, lock_mode);
                xfs_lock_inodes(i_tab, *num_inodes, 0, XFS_ILOCK_SHARED);
        }

        /*
         * Set the return value. Null out any unused entries in i_tab.
         */
        *ipp1 = *ipp2 = NULL;
        for (i=0; i < *num_inodes; i++) {
                if (i_tab[i]->i_ino == inum1) {
                        *ipp1 = i_tab[i];
                }
                if (i_tab[i]->i_ino == inum2) {
                        *ipp2 = i_tab[i];
                }
        }
        for (;i < 4; i++) {
                i_tab[i] = NULL;
        }
        return 0;
}

/*
 * xfs_rename
 */
int
xfs_rename(
        bhv_desc_t      *src_dir_bdp,
        bhv_vname_t     *src_vname,
        bhv_vnode_t     *target_dir_vp,
        bhv_vname_t     *target_vname,
        cred_t          *credp)
{
        xfs_trans_t     *tp;
        xfs_inode_t     *src_dp, *target_dp, *src_ip, *target_ip;
        xfs_mount_t     *mp;
        int             new_parent;             /* moving to a new dir */
        int             src_is_directory;       /* src_name is a directory */
        int             error;
        xfs_bmap_free_t free_list;
        xfs_fsblock_t   first_block;
        int             cancel_flags;
        int             committed;
        xfs_inode_t     *inodes[4];
        int             target_ip_dropped = 0;  /* dropped target_ip link? */
        bhv_vnode_t     *src_dir_vp;
        int             spaceres;
        int             target_link_zero = 0;
        int             num_inodes;
        char            *src_name = VNAME(src_vname);
        char            *target_name = VNAME(target_vname);
        int             src_namelen = VNAMELEN(src_vname);
        int             target_namelen = VNAMELEN(target_vname);

        src_dir_vp = BHV_TO_VNODE(src_dir_bdp);
        vn_trace_entry(src_dir_vp, "xfs_rename", (inst_t *)__return_address);
        vn_trace_entry(target_dir_vp, "xfs_rename", (inst_t *)__return_address);

        /*
         * Find the XFS behavior descriptor for the target directory
         * vnode since it was not handed to us.
         */
        target_dp = xfs_vtoi(target_dir_vp);
        if (target_dp == NULL) {
                return XFS_ERROR(EXDEV);
        }

        src_dp = XFS_BHVTOI(src_dir_bdp);
        mp = src_dp->i_mount;

        if (DM_EVENT_ENABLED(src_dir_vp->v_vfsp, src_dp, DM_EVENT_RENAME) ||
            DM_EVENT_ENABLED(target_dir_vp->v_vfsp,
                                target_dp, DM_EVENT_RENAME)) {
                error = XFS_SEND_NAMESP(mp, DM_EVENT_RENAME,
                                        src_dir_vp, DM_RIGHT_NULL,
                                        target_dir_vp, DM_RIGHT_NULL,
                                        src_name, target_name,
                                        0, 0, 0);
                if (error) {
                        return error;
                }
        }
        /* Return through std_return after this point. */

        /*
         * Lock all the participating inodes. Depending upon whether
         * the target_name exists in the target directory, and
         * whether the target directory is the same as the source
         * directory, we can lock from 2 to 4 inodes.
         * xfs_lock_for_rename() will return ENOENT if src_name
         * does not exist in the source directory.
         */
        tp = NULL;
        error = xfs_lock_for_rename(src_dp, target_dp, src_vname,
                        target_vname, &src_ip, &target_ip, inodes,
                        &num_inodes);

        if (error) {
                /*
                 * We have nothing locked, no inode references, and
                 * no transaction, so just get out.
                 */
                goto std_return;
        }

        ASSERT(src_ip != NULL);

        if ((src_ip->i_d.di_mode & S_IFMT) == S_IFDIR) {
                /*
                 * Check for link count overflow on target_dp
                 */
                if (target_ip == NULL && (src_dp != target_dp) &&
                    target_dp->i_d.di_nlink >= XFS_MAXLINK) {
                        error = XFS_ERROR(EMLINK);
                        xfs_rename_unlock4(inodes, XFS_ILOCK_SHARED);
                        goto rele_return;
                }
        }

        /*
         * If we are using project inheritance, we only allow renames
         * into our tree when the project IDs are the same; else the
         * tree quota mechanism would be circumvented.
         */
        if (unlikely((target_dp->i_d.di_flags & XFS_DIFLAG_PROJINHERIT) &&
                     (target_dp->i_d.di_projid != src_ip->i_d.di_projid))) {
                error = XFS_ERROR(EXDEV);
                xfs_rename_unlock4(inodes, XFS_ILOCK_SHARED);
                goto rele_return;
        }

        new_parent = (src_dp != target_dp);
        src_is_directory = ((src_ip->i_d.di_mode & S_IFMT) == S_IFDIR);

        /*
         * Drop the locks on our inodes so that we can start the transaction.
         */
        xfs_rename_unlock4(inodes, XFS_ILOCK_SHARED);

        XFS_BMAP_INIT(&free_list, &first_block);
        tp = xfs_trans_alloc(mp, XFS_TRANS_RENAME);
        cancel_flags = XFS_TRANS_RELEASE_LOG_RES;
        spaceres = XFS_RENAME_SPACE_RES(mp, target_namelen);
        error = xfs_trans_reserve(tp, spaceres, XFS_RENAME_LOG_RES(mp), 0,
                        XFS_TRANS_PERM_LOG_RES, XFS_RENAME_LOG_COUNT);
        if (error == ENOSPC) {
                spaceres = 0;
                error = xfs_trans_reserve(tp, 0, XFS_RENAME_LOG_RES(mp), 0,
                                XFS_TRANS_PERM_LOG_RES, XFS_RENAME_LOG_COUNT);
        }
        if (error) {
                xfs_trans_cancel(tp, 0);
                goto rele_return;
        }

        /*
         * Attach the dquots to the inodes
         */
        if ((error = XFS_QM_DQVOPRENAME(mp, inodes))) {
                xfs_trans_cancel(tp, cancel_flags);
                goto rele_return;
        }

        /*
         * Reacquire the inode locks we dropped above.
         */
        xfs_lock_inodes(inodes, num_inodes, 0, XFS_ILOCK_EXCL);

        /*
         * Join all the inodes to the transaction. From this point on,
         * we can rely on either trans_commit or trans_cancel to unlock
         * them.  Note that we need to add a vnode reference to the
         * directories since trans_commit & trans_cancel will decrement
         * them when they unlock the inodes.  Also, we need to be careful
         * not to add an inode to the transaction more than once.
         */
        VN_HOLD(src_dir_vp);
        xfs_trans_ijoin(tp, src_dp, XFS_ILOCK_EXCL);
        if (new_parent) {
                VN_HOLD(target_dir_vp);
                xfs_trans_ijoin(tp, target_dp, XFS_ILOCK_EXCL);
        }
        if ((src_ip != src_dp) && (src_ip != target_dp)) {
                xfs_trans_ijoin(tp, src_ip, XFS_ILOCK_EXCL);
        }
        if ((target_ip != NULL) &&
            (target_ip != src_ip) &&
            (target_ip != src_dp) &&
            (target_ip != target_dp)) {
                xfs_trans_ijoin(tp, target_ip, XFS_ILOCK_EXCL);
        }

        /*
         * Set up the target.
         */
        if (target_ip == NULL) {
                /*
                 * If there's no space reservation, check the entry will
                 * fit before actually inserting it.
                 */
                if (spaceres == 0 &&
                    (error = xfs_dir_canenter(tp, target_dp, target_name,
                                                target_namelen)))
                        goto error_return;
                /*
                 * If target does not exist and the rename crosses
                 * directories, adjust the target directory link count
                 * to account for the ".." reference from the new entry.
                 */
                error = xfs_dir_createname(tp, target_dp, target_name,
                                           target_namelen, src_ip->i_ino,
                                           &first_block, &free_list, spaceres);
                if (error == ENOSPC)
                        goto error_return;
                if (error)
                        goto abort_return;
                xfs_ichgtime(target_dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);

                if (new_parent && src_is_directory) {
                        error = xfs_bumplink(tp, target_dp);
                        if (error)
                                goto abort_return;
                }
        } else { /* target_ip != NULL */
                /*
                 * If target exists and it's a directory, check that both
                 * target and source are directories and that target can be
                 * destroyed, or that neither is a directory.
                 */
                if ((target_ip->i_d.di_mode & S_IFMT) == S_IFDIR) {
                        /*
                         * Make sure target dir is empty.
                         */
                        if (!(xfs_dir_isempty(target_ip)) ||
                            (target_ip->i_d.di_nlink > 2)) {
                                error = XFS_ERROR(EEXIST);
                                goto error_return;
                        }
                }

                /*
                 * Link the source inode under the target name.
                 * If the source inode is a directory and we are moving
                 * it across directories, its ".." entry will be
                 * inconsistent until we replace that down below.
                 *
                 * In case there is already an entry with the same
                 * name at the destination directory, remove it first.
                 */
                error = xfs_dir_replace(tp, target_dp, target_name,
                                        target_namelen, src_ip->i_ino,
                                        &first_block, &free_list, spaceres);
                if (error)
                        goto abort_return;
                xfs_ichgtime(target_dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);

                /*
                 * Decrement the link count on the target since the target
                 * dir no longer points to it.
                 */
                error = xfs_droplink(tp, target_ip);
                if (error)
                        goto abort_return;
                target_ip_dropped = 1;

                if (src_is_directory) {
                        /*
                         * Drop the link from the old "." entry.
                         */
                        error = xfs_droplink(tp, target_ip);
                        if (error)
                                goto abort_return;
                }

                /* Do this test while we still hold the locks */
                target_link_zero = (target_ip)->i_d.di_nlink==0;

        } /* target_ip != NULL */

        /*
         * Remove the source.
         */
        if (new_parent && src_is_directory) {
                /*
                 * Rewrite the ".." entry to point to the new
                 * directory.
                 */
                error = xfs_dir_replace(tp, src_ip, "..", 2, target_dp->i_ino,
                                        &first_block, &free_list, spaceres);
                ASSERT(error != EEXIST);
                if (error)
                        goto abort_return;
                xfs_ichgtime(src_ip, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);

        } else {
                /*
                 * We always want to hit the ctime on the source inode.
                 * We do it in the if clause above for the 'new_parent &&
                 * src_is_directory' case, and here we get all the other
                 * cases.  This isn't strictly required by the standards
                 * since the source inode isn't really being changed,
                 * but old unix file systems did it and some incremental
                 * backup programs won't work without it.
                 */
                xfs_ichgtime(src_ip, XFS_ICHGTIME_CHG);
        }

        /*
         * Adjust the link count on src_dp.  This is necessary when
         * renaming a directory, either within one parent when
         * the target existed, or across two parent directories.
         */
        if (src_is_directory && (new_parent || target_ip != NULL)) {

                /*
                 * Decrement link count on src_directory since the
                 * entry that's moved no longer points to it.
                 */
                error = xfs_droplink(tp, src_dp);
                if (error)
                        goto abort_return;
        }

        error = xfs_dir_removename(tp, src_dp, src_name, src_namelen,
                        src_ip->i_ino, &first_block, &free_list, spaceres);
        if (error)
                goto abort_return;
        xfs_ichgtime(src_dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);

        /*
         * Update the generation counts on all the directory inodes
         * that we're modifying.
         */
        src_dp->i_gen++;
        xfs_trans_log_inode(tp, src_dp, XFS_ILOG_CORE);

        if (new_parent) {
                target_dp->i_gen++;
                xfs_trans_log_inode(tp, target_dp, XFS_ILOG_CORE);
        }

        /*
         * If there was a target inode, take an extra reference on
         * it here so that it doesn't go to xfs_inactive() from
         * within the commit.
         */
        if (target_ip != NULL) {
                IHOLD(target_ip);
        }

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

        /*
         * Take refs. for vop_link_removed calls below.  No need to worry
         * about directory refs. because the caller holds them.
         *
         * Do holds before the xfs_bmap_finish since it might rele them down
         * to zero.
         */

        if (target_ip_dropped)
                IHOLD(target_ip);
        IHOLD(src_ip);

        error = xfs_bmap_finish(&tp, &free_list, &committed);
        if (error) {
                xfs_bmap_cancel(&free_list);
                xfs_trans_cancel(tp, (XFS_TRANS_RELEASE_LOG_RES |
                                 XFS_TRANS_ABORT));
                if (target_ip != NULL) {
                        IRELE(target_ip);
                }
                if (target_ip_dropped) {
                        IRELE(target_ip);
                }
                IRELE(src_ip);
                goto std_return;
        }

        /*
         * trans_commit will unlock src_ip, target_ip & decrement
         * the vnode references.
         */
        error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES, NULL);
        if (target_ip != NULL) {
                xfs_refcache_purge_ip(target_ip);
                IRELE(target_ip);
        }
        /*
         * Let interposed file systems know about removed links.
         */
        if (target_ip_dropped) {
                bhv_vop_link_removed(XFS_ITOV(target_ip), target_dir_vp,
                                        target_link_zero);
                IRELE(target_ip);
        }

        IRELE(src_ip);

        /* Fall through to std_return with error = 0 or errno from
         * xfs_trans_commit      */
std_return:
        if (DM_EVENT_ENABLED(src_dir_vp->v_vfsp, src_dp, DM_EVENT_POSTRENAME) ||
            DM_EVENT_ENABLED(target_dir_vp->v_vfsp,
                                target_dp, DM_EVENT_POSTRENAME)) {
                (void) XFS_SEND_NAMESP (mp, DM_EVENT_POSTRENAME,
                                        src_dir_vp, DM_RIGHT_NULL,
                                        target_dir_vp, DM_RIGHT_NULL,
                                        src_name, target_name,
                                        0, error, 0);
        }
        return error;

 abort_return:
        cancel_flags |= XFS_TRANS_ABORT;
        /* FALLTHROUGH */
 error_return:
        xfs_bmap_cancel(&free_list);
        xfs_trans_cancel(tp, cancel_flags);
        goto std_return;

 rele_return:
        IRELE(src_ip);
        if (target_ip != NULL) {
                IRELE(target_ip);
        }
        goto std_return;
}