[PATCH] powerpc: Add flattened device tree documentation

[linux-2.6/zen-sources.git] / fs / xfs / xfs_utils.c

/*
 * Copyright (c) 2000-2002,2005 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_bit.h"
#include "xfs_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir.h"
#include "xfs_dir2.h"
#include "xfs_dmapi.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_dir_sf.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_rw.h"
#include "xfs_itable.h"
#include "xfs_utils.h"

/*
 * xfs_get_dir_entry is used to get a reference to an inode given
 * its parent directory inode and the name of the file.  It does
 * not lock the child inode, and it unlocks the directory before
 * returning.  The directory's generation number is returned for
 * use by a later call to xfs_lock_dir_and_entry.
 */
int
xfs_get_dir_entry(
        vname_t         *dentry,
        xfs_inode_t     **ipp)
{
        vnode_t         *vp;

        vp = VNAME_TO_VNODE(dentry);

        *ipp = xfs_vtoi(vp);
        if (!*ipp)
                return XFS_ERROR(ENOENT);
        VN_HOLD(vp);
        return 0;
}

int
xfs_dir_lookup_int(
        bhv_desc_t      *dir_bdp,
        uint            lock_mode,
        vname_t         *dentry,
        xfs_ino_t       *inum,
        xfs_inode_t     **ipp)
{
        vnode_t         *dir_vp;
        xfs_inode_t     *dp;
        int             error;

        dir_vp = BHV_TO_VNODE(dir_bdp);
        vn_trace_entry(dir_vp, __FUNCTION__, (inst_t *)__return_address);

        dp = XFS_BHVTOI(dir_bdp);

        error = XFS_DIR_LOOKUP(dp->i_mount, NULL, dp,
                                VNAME(dentry), VNAMELEN(dentry), inum);
        if (!error) {
                /*
                 * Unlock the directory. We do this because we can't
                 * hold the directory lock while doing the vn_get()
                 * in xfs_iget().  Doing so could cause us to hold
                 * a lock while waiting for the inode to finish
                 * being inactive while it's waiting for a log
                 * reservation in the inactive routine.
                 */
                xfs_iunlock(dp, lock_mode);
                error = xfs_iget(dp->i_mount, NULL, *inum, 0, 0, ipp, 0);
                xfs_ilock(dp, lock_mode);

                if (error) {
                        *ipp = NULL;
                } else if ((*ipp)->i_d.di_mode == 0) {
                        /*
                         * The inode has been freed.  Something is
                         * wrong so just get out of here.
                         */
                        xfs_iunlock(dp, lock_mode);
                        xfs_iput_new(*ipp, 0);
                        *ipp = NULL;
                        xfs_ilock(dp, lock_mode);
                        error = XFS_ERROR(ENOENT);
                }
        }
        return error;
}

/*
 * Allocates a new inode from disk and return a pointer to the
 * incore copy. This routine will internally commit the current
 * transaction and allocate a new one if the Space Manager needed
 * to do an allocation to replenish the inode free-list.
 *
 * This routine is designed to be called from xfs_create and
 * xfs_create_dir.
 *
 */
int
xfs_dir_ialloc(
        xfs_trans_t     **tpp,          /* input: current transaction;
                                           output: may be a new transaction. */
        xfs_inode_t     *dp,            /* directory within whose allocate
                                           the inode. */
        mode_t          mode,
        xfs_nlink_t     nlink,
        xfs_dev_t       rdev,
        cred_t          *credp,
        prid_t          prid,           /* project id */
        int             okalloc,        /* ok to allocate new space */
        xfs_inode_t     **ipp,          /* pointer to inode; it will be
                                           locked. */
        int             *committed)

{
        xfs_trans_t     *tp;
        xfs_trans_t     *ntp;
        xfs_inode_t     *ip;
        xfs_buf_t       *ialloc_context = NULL;
        boolean_t       call_again = B_FALSE;
        int             code;
        uint            log_res;
        uint            log_count;
        void            *dqinfo;
        uint            tflags;

        tp = *tpp;
        ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);

        /*
         * xfs_ialloc will return a pointer to an incore inode if
         * the Space Manager has an available inode on the free
         * list. Otherwise, it will do an allocation and replenish
         * the freelist.  Since we can only do one allocation per
         * transaction without deadlocks, we will need to commit the
         * current transaction and start a new one.  We will then
         * need to call xfs_ialloc again to get the inode.
         *
         * If xfs_ialloc did an allocation to replenish the freelist,
         * it returns the bp containing the head of the freelist as
         * ialloc_context. We will hold a lock on it across the
         * transaction commit so that no other process can steal
         * the inode(s) that we've just allocated.
         */
        code = xfs_ialloc(tp, dp, mode, nlink, rdev, credp, prid, okalloc,
                          &ialloc_context, &call_again, &ip);

        /*
         * Return an error if we were unable to allocate a new inode.
         * This should only happen if we run out of space on disk or
         * encounter a disk error.
         */
        if (code) {
                *ipp = NULL;
                return code;
        }
        if (!call_again && (ip == NULL)) {
                *ipp = NULL;
                return XFS_ERROR(ENOSPC);
        }

        /*
         * If call_again is set, then we were unable to get an
         * inode in one operation.  We need to commit the current
         * transaction and call xfs_ialloc() again.  It is guaranteed
         * to succeed the second time.
         */
        if (call_again) {

                /*
                 * Normally, xfs_trans_commit releases all the locks.
                 * We call bhold to hang on to the ialloc_context across
                 * the commit.  Holding this buffer prevents any other
                 * processes from doing any allocations in this
                 * allocation group.
                 */
                xfs_trans_bhold(tp, ialloc_context);
                /*
                 * Save the log reservation so we can use
                 * them in the next transaction.
                 */
                log_res = xfs_trans_get_log_res(tp);
                log_count = xfs_trans_get_log_count(tp);

                /*
                 * We want the quota changes to be associated with the next
                 * transaction, NOT this one. So, detach the dqinfo from this
                 * and attach it to the next transaction.
                 */
                dqinfo = NULL;
                tflags = 0;
                if (tp->t_dqinfo) {
                        dqinfo = (void *)tp->t_dqinfo;
                        tp->t_dqinfo = NULL;
                        tflags = tp->t_flags & XFS_TRANS_DQ_DIRTY;
                        tp->t_flags &= ~(XFS_TRANS_DQ_DIRTY);
                }

                ntp = xfs_trans_dup(tp);
                code = xfs_trans_commit(tp, 0, NULL);
                tp = ntp;
                if (committed != NULL) {
                        *committed = 1;
                }
                /*
                 * If we get an error during the commit processing,
                 * release the buffer that is still held and return
                 * to the caller.
                 */
                if (code) {
                        xfs_buf_relse(ialloc_context);
                        if (dqinfo) {
                                tp->t_dqinfo = dqinfo;
                                XFS_TRANS_FREE_DQINFO(tp->t_mountp, tp);
                        }
                        *tpp = ntp;
                        *ipp = NULL;
                        return code;
                }
                code = xfs_trans_reserve(tp, 0, log_res, 0,
                                         XFS_TRANS_PERM_LOG_RES, log_count);
                /*
                 * Re-attach the quota info that we detached from prev trx.
                 */
                if (dqinfo) {
                        tp->t_dqinfo = dqinfo;
                        tp->t_flags |= tflags;
                }

                if (code) {
                        xfs_buf_relse(ialloc_context);
                        *tpp = ntp;
                        *ipp = NULL;
                        return code;
                }
                xfs_trans_bjoin(tp, ialloc_context);

                /*
                 * Call ialloc again. Since we've locked out all
                 * other allocations in this allocation group,
                 * this call should always succeed.
                 */
                code = xfs_ialloc(tp, dp, mode, nlink, rdev, credp, prid,
                                  okalloc, &ialloc_context, &call_again, &ip);

                /*
                 * If we get an error at this point, return to the caller
                 * so that the current transaction can be aborted.
                 */
                if (code) {
                        *tpp = tp;
                        *ipp = NULL;
                        return code;
                }
                ASSERT ((!call_again) && (ip != NULL));

        } else {
                if (committed != NULL) {
                        *committed = 0;
                }
        }

        *ipp = ip;
        *tpp = tp;

        return 0;
}

/*
 * Decrement the link count on an inode & log the change.
 * If this causes the link count to go to zero, initiate the
 * logging activity required to truncate a file.
 */
int                             /* error */
xfs_droplink(
        xfs_trans_t *tp,
        xfs_inode_t *ip)
{
        int     error;

        xfs_ichgtime(ip, XFS_ICHGTIME_CHG);

        ASSERT (ip->i_d.di_nlink > 0);
        ip->i_d.di_nlink--;
        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);

        error = 0;
        if (ip->i_d.di_nlink == 0) {
                /*
                 * We're dropping the last link to this file.
                 * Move the on-disk inode to the AGI unlinked list.
                 * From xfs_inactive() we will pull the inode from
                 * the list and free it.
                 */
                error = xfs_iunlink(tp, ip);
        }
        return error;
}

/*
 * This gets called when the inode's version needs to be changed from 1 to 2.
 * Currently this happens when the nlink field overflows the old 16-bit value
 * or when chproj is called to change the project for the first time.
 * As a side effect the superblock version will also get rev'd
 * to contain the NLINK bit.
 */
void
xfs_bump_ino_vers2(
        xfs_trans_t     *tp,
        xfs_inode_t     *ip)
{
        xfs_mount_t     *mp;
        unsigned long           s;

        ASSERT(ismrlocked (&ip->i_lock, MR_UPDATE));
        ASSERT(ip->i_d.di_version == XFS_DINODE_VERSION_1);

        ip->i_d.di_version = XFS_DINODE_VERSION_2;
        ip->i_d.di_onlink = 0;
        memset(&(ip->i_d.di_pad[0]), 0, sizeof(ip->i_d.di_pad));
        mp = tp->t_mountp;
        if (!XFS_SB_VERSION_HASNLINK(&mp->m_sb)) {
                s = XFS_SB_LOCK(mp);
                if (!XFS_SB_VERSION_HASNLINK(&mp->m_sb)) {
                        XFS_SB_VERSION_ADDNLINK(&mp->m_sb);
                        XFS_SB_UNLOCK(mp, s);
                        xfs_mod_sb(tp, XFS_SB_VERSIONNUM);
                } else {
                        XFS_SB_UNLOCK(mp, s);
                }
        }
        /* Caller must log the inode */
}

/*
 * Increment the link count on an inode & log the change.
 */
int
xfs_bumplink(
        xfs_trans_t *tp,
        xfs_inode_t *ip)
{
        if (ip->i_d.di_nlink >= XFS_MAXLINK)
                return XFS_ERROR(EMLINK);
        xfs_ichgtime(ip, XFS_ICHGTIME_CHG);

        ASSERT(ip->i_d.di_nlink > 0);
        ip->i_d.di_nlink++;
        if ((ip->i_d.di_version == XFS_DINODE_VERSION_1) &&
            (ip->i_d.di_nlink > XFS_MAXLINK_1)) {
                /*
                 * The inode has increased its number of links beyond
                 * what can fit in an old format inode.  It now needs
                 * to be converted to a version 2 inode with a 32 bit
                 * link count.  If this is the first inode in the file
                 * system to do this, then we need to bump the superblock
                 * version number as well.
                 */
                xfs_bump_ino_vers2(tp, ip);
        }

        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
        return 0;
}

/*
 * Try to truncate the given file to 0 length.  Currently called
 * only out of xfs_remove when it has to truncate a file to free
 * up space for the remove to proceed.
 */
int
xfs_truncate_file(
        xfs_mount_t     *mp,
        xfs_inode_t     *ip)
{
        xfs_trans_t     *tp;
        int             error;

#ifdef QUOTADEBUG
        /*
         * This is called to truncate the quotainodes too.
         */
        if (XFS_IS_UQUOTA_ON(mp)) {
                if (ip->i_ino != mp->m_sb.sb_uquotino)
                        ASSERT(ip->i_udquot);
        }
        if (XFS_IS_OQUOTA_ON(mp)) {
                if (ip->i_ino != mp->m_sb.sb_gquotino)
                        ASSERT(ip->i_gdquot);
        }
#endif
        /*
         * Make the call to xfs_itruncate_start before starting the
         * transaction, because we cannot make the call while we're
         * in a transaction.
         */
        xfs_ilock(ip, XFS_IOLOCK_EXCL);
        xfs_itruncate_start(ip, XFS_ITRUNC_DEFINITE, (xfs_fsize_t)0);

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

        /*
         * Follow the normal truncate locking protocol.  Since we
         * hold the inode in the transaction, we know that it's number
         * of references will stay constant.
         */
        xfs_ilock(ip, XFS_ILOCK_EXCL);
        xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);
        xfs_trans_ihold(tp, ip);
        /*
         * Signal a sync xaction.  The only case where that isn't
         * the case is if we're truncating an already unlinked file
         * on a wsync fs.  In that case, we know the blocks can't
         * reappear in the file because the links to file are
         * permanently toast.  Currently, we're always going to
         * want a sync transaction because this code is being
         * called from places where nlink is guaranteed to be 1
         * but I'm leaving the tests in to protect against future
         * changes -- rcc.
         */
        error = xfs_itruncate_finish(&tp, ip, (xfs_fsize_t)0,
                                     XFS_DATA_FORK,
                                     ((ip->i_d.di_nlink != 0 ||
                                       !(mp->m_flags & XFS_MOUNT_WSYNC))
                                      ? 1 : 0));
        if (error) {
                xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES |
                                 XFS_TRANS_ABORT);
        } else {
                xfs_ichgtime(ip, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
                error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES,
                                         NULL);
        }
        xfs_iunlock(ip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);

        return error;
}