Linux-2.6.12-rc2

[thirdparty/linux.git] / fs / jfs / jfs_extent.c

/*
 *   Copyright (C) International Business Machines Corp., 2000-2004
 *
 *   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; either version 2 of the License, or 
 *   (at your option) any later version.
 * 
 *   This program is distributed in the hope that it will 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 to the Free Software 
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/fs.h>
#include <linux/quotaops.h>
#include "jfs_incore.h"
#include "jfs_superblock.h"
#include "jfs_dmap.h"
#include "jfs_extent.h"
#include "jfs_debug.h"

/*
 * forward references
 */
static int extBalloc(struct inode *, s64, s64 *, s64 *);
#ifdef _NOTYET
static int extBrealloc(struct inode *, s64, s64, s64 *, s64 *);
#endif
static s64 extRoundDown(s64 nb);

/*
 * external references
 */
extern int jfs_commit_inode(struct inode *, int);


#define DPD(a)          (printk("(a): %d\n",(a)))
#define DPC(a)          (printk("(a): %c\n",(a)))
#define DPL1(a)                                 \
{                                               \
        if ((a) >> 32)                          \
                printk("(a): %x%08x  ",(a));    \
        else                                    \
                printk("(a): %x  ",(a) << 32);  \
}
#define DPL(a)                                  \
{                                               \
        if ((a) >> 32)                          \
                printk("(a): %x%08x\n",(a));    \
        else                                    \
                printk("(a): %x\n",(a) << 32);  \
}

#define DPD1(a)         (printk("(a): %d  ",(a)))
#define DPX(a)          (printk("(a): %08x\n",(a)))
#define DPX1(a)         (printk("(a): %08x  ",(a)))
#define DPS(a)          (printk("%s\n",(a)))
#define DPE(a)          (printk("\nENTERING: %s\n",(a)))
#define DPE1(a)          (printk("\nENTERING: %s",(a)))
#define DPS1(a)         (printk("  %s  ",(a)))


/*
 * NAME:        extAlloc()
 *
 * FUNCTION:    allocate an extent for a specified page range within a
 *              file.
 *
 * PARAMETERS:
 *      ip      - the inode of the file.
 *      xlen    - requested extent length.
 *      pno     - the starting page number with the file.
 *      xp      - pointer to an xad.  on entry, xad describes an
 *                extent that is used as an allocation hint if the
 *                xaddr of the xad is non-zero.  on successful exit,
 *                the xad describes the newly allocated extent.
 *      abnr    - boolean_t indicating whether the newly allocated extent
 *                should be marked as allocated but not recorded.
 *
 * RETURN VALUES:
 *      0       - success
 *      -EIO    - i/o error.
 *      -ENOSPC - insufficient disk resources.
 */
int
extAlloc(struct inode *ip, s64 xlen, s64 pno, xad_t * xp, boolean_t abnr)
{
        struct jfs_sb_info *sbi = JFS_SBI(ip->i_sb);
        s64 nxlen, nxaddr, xoff, hint, xaddr = 0;
        int rc;
        int xflag;

        /* This blocks if we are low on resources */
        txBeginAnon(ip->i_sb);

        /* Avoid race with jfs_commit_inode() */
        down(&JFS_IP(ip)->commit_sem);

        /* validate extent length */
        if (xlen > MAXXLEN)
                xlen = MAXXLEN;

        /* get the page's starting extent offset */
        xoff = pno << sbi->l2nbperpage;

        /* check if an allocation hint was provided */
        if ((hint = addressXAD(xp))) {
                /* get the size of the extent described by the hint */
                nxlen = lengthXAD(xp);

                /* check if the hint is for the portion of the file
                 * immediately previous to the current allocation
                 * request and if hint extent has the same abnr
                 * value as the current request.  if so, we can
                 * extend the hint extent to include the current
                 * extent if we can allocate the blocks immediately
                 * following the hint extent.
                 */
                if (offsetXAD(xp) + nxlen == xoff &&
                    abnr == ((xp->flag & XAD_NOTRECORDED) ? TRUE : FALSE))
                        xaddr = hint + nxlen;

                /* adjust the hint to the last block of the extent */
                hint += (nxlen - 1);
        }

        /* allocate the disk blocks for the extent.  initially, extBalloc()
         * will try to allocate disk blocks for the requested size (xlen). 
         * if this fails (xlen contigious free blocks not avaliable), it'll
         * try to allocate a smaller number of blocks (producing a smaller
         * extent), with this smaller number of blocks consisting of the
         * requested number of blocks rounded down to the next smaller
         * power of 2 number (i.e. 16 -> 8).  it'll continue to round down
         * and retry the allocation until the number of blocks to allocate
         * is smaller than the number of blocks per page.
         */
        nxlen = xlen;
        if ((rc = extBalloc(ip, hint ? hint : INOHINT(ip), &nxlen, &nxaddr))) {
                up(&JFS_IP(ip)->commit_sem);
                return (rc);
        }

        /* Allocate blocks to quota. */
        if (DQUOT_ALLOC_BLOCK(ip, nxlen)) {
                dbFree(ip, nxaddr, (s64) nxlen);
                up(&JFS_IP(ip)->commit_sem);
                return -EDQUOT;
        }

        /* determine the value of the extent flag */
        xflag = (abnr == TRUE) ? XAD_NOTRECORDED : 0;

        /* if we can extend the hint extent to cover the current request, 
         * extend it.  otherwise, insert a new extent to
         * cover the current request.
         */
        if (xaddr && xaddr == nxaddr)
                rc = xtExtend(0, ip, xoff, (int) nxlen, 0);
        else
                rc = xtInsert(0, ip, xflag, xoff, (int) nxlen, &nxaddr, 0);

        /* if the extend or insert failed, 
         * free the newly allocated blocks and return the error.
         */
        if (rc) {
                dbFree(ip, nxaddr, nxlen);
                DQUOT_FREE_BLOCK(ip, nxlen);
                up(&JFS_IP(ip)->commit_sem);
                return (rc);
        }

        /* set the results of the extent allocation */
        XADaddress(xp, nxaddr);
        XADlength(xp, nxlen);
        XADoffset(xp, xoff);
        xp->flag = xflag;

        mark_inode_dirty(ip);

        up(&JFS_IP(ip)->commit_sem);
        /*
         * COMMIT_SyncList flags an anonymous tlock on page that is on
         * sync list.
         * We need to commit the inode to get the page written disk.
         */
        if (test_and_clear_cflag(COMMIT_Synclist,ip))
                jfs_commit_inode(ip, 0);

        return (0);
}


#ifdef _NOTYET
/*
 * NAME:        extRealloc()
 *
 * FUNCTION:    extend the allocation of a file extent containing a
 *              partial back last page.
 *
 * PARAMETERS:
 *      ip      - the inode of the file.
 *      cp      - cbuf for the partial backed last page.
 *      xlen    - request size of the resulting extent.
 *      xp      - pointer to an xad. on successful exit, the xad
 *                describes the newly allocated extent.
 *      abnr    - boolean_t indicating whether the newly allocated extent
 *                should be marked as allocated but not recorded.
 *
 * RETURN VALUES:
 *      0       - success
 *      -EIO    - i/o error.
 *      -ENOSPC - insufficient disk resources.
 */
int extRealloc(struct inode *ip, s64 nxlen, xad_t * xp, boolean_t abnr)
{
        struct super_block *sb = ip->i_sb;
        s64 xaddr, xlen, nxaddr, delta, xoff;
        s64 ntail, nextend, ninsert;
        int rc, nbperpage = JFS_SBI(sb)->nbperpage;
        int xflag;

        /* This blocks if we are low on resources */
        txBeginAnon(ip->i_sb);

        down(&JFS_IP(ip)->commit_sem);
        /* validate extent length */
        if (nxlen > MAXXLEN)
                nxlen = MAXXLEN;

        /* get the extend (partial) page's disk block address and
         * number of blocks.
         */
        xaddr = addressXAD(xp);
        xlen = lengthXAD(xp);
        xoff = offsetXAD(xp);

        /* if the extend page is abnr and if the request is for
         * the extent to be allocated and recorded, 
         * make the page allocated and recorded.
         */
        if ((xp->flag & XAD_NOTRECORDED) && !abnr) {
                xp->flag = 0;
                if ((rc = xtUpdate(0, ip, xp)))
                        goto exit;
        }

        /* try to allocated the request number of blocks for the
         * extent.  dbRealloc() first tries to satisfy the request
         * by extending the allocation in place. otherwise, it will
         * try to allocate a new set of blocks large enough for the
         * request.  in satisfying a request, dbReAlloc() may allocate
         * less than what was request but will always allocate enough
         * space as to satisfy the extend page.
         */
        if ((rc = extBrealloc(ip, xaddr, xlen, &nxlen, &nxaddr)))
                goto exit;

        /* Allocat blocks to quota. */
        if (DQUOT_ALLOC_BLOCK(ip, nxlen)) {
                dbFree(ip, nxaddr, (s64) nxlen);
                up(&JFS_IP(ip)->commit_sem);
                return -EDQUOT;
        }

        delta = nxlen - xlen;

        /* check if the extend page is not abnr but the request is abnr
         * and the allocated disk space is for more than one page.  if this
         * is the case, there is a miss match of abnr between the extend page
         * and the one or more pages following the extend page.  as a result,
         * two extents will have to be manipulated. the first will be that
         * of the extent of the extend page and will be manipulated thru
         * an xtExtend() or an xtTailgate(), depending upon whether the
         * disk allocation occurred as an inplace extension.  the second
         * extent will be manipulated (created) through an xtInsert() and
         * will be for the pages following the extend page.
         */
        if (abnr && (!(xp->flag & XAD_NOTRECORDED)) && (nxlen > nbperpage)) {
                ntail = nbperpage;
                nextend = ntail - xlen;
                ninsert = nxlen - nbperpage;

                xflag = XAD_NOTRECORDED;
        } else {
                ntail = nxlen;
                nextend = delta;
                ninsert = 0;

                xflag = xp->flag;
        }

        /* if we were able to extend the disk allocation in place,
         * extend the extent.  otherwise, move the extent to a
         * new disk location.
         */
        if (xaddr == nxaddr) {
                /* extend the extent */
                if ((rc = xtExtend(0, ip, xoff + xlen, (int) nextend, 0))) {
                        dbFree(ip, xaddr + xlen, delta);
                        DQUOT_FREE_BLOCK(ip, nxlen);
                        goto exit;
                }
        } else {
                /*
                 * move the extent to a new location:
                 *
                 * xtTailgate() accounts for relocated tail extent;
                 */
                if ((rc = xtTailgate(0, ip, xoff, (int) ntail, nxaddr, 0))) {
                        dbFree(ip, nxaddr, nxlen);
                        DQUOT_FREE_BLOCK(ip, nxlen);
                        goto exit;
                }
        }


        /* check if we need to also insert a new extent */
        if (ninsert) {
                /* perform the insert.  if it fails, free the blocks
                 * to be inserted and make it appear that we only did
                 * the xtExtend() or xtTailgate() above.
                 */
                xaddr = nxaddr + ntail;
                if (xtInsert (0, ip, xflag, xoff + ntail, (int) ninsert,
                              &xaddr, 0)) {
                        dbFree(ip, xaddr, (s64) ninsert);
                        delta = nextend;
                        nxlen = ntail;
                        xflag = 0;
                }
        }

        /* set the return results */
        XADaddress(xp, nxaddr);
        XADlength(xp, nxlen);
        XADoffset(xp, xoff);
        xp->flag = xflag;

        mark_inode_dirty(ip);
exit:
        up(&JFS_IP(ip)->commit_sem);
        return (rc);
}
#endif                  /* _NOTYET */


/*
 * NAME:        extHint()
 *
 * FUNCTION:    produce an extent allocation hint for a file offset.
 *
 * PARAMETERS:
 *      ip      - the inode of the file.
 *      offset  - file offset for which the hint is needed.
 *      xp      - pointer to the xad that is to be filled in with
 *                the hint.
 *
 * RETURN VALUES:
 *      0       - success
 *      -EIO    - i/o error.
 */
int extHint(struct inode *ip, s64 offset, xad_t * xp)
{
        struct super_block *sb = ip->i_sb;
        struct xadlist xadl;
        struct lxdlist lxdl;
        lxd_t lxd;
        s64 prev;
        int rc, nbperpage = JFS_SBI(sb)->nbperpage;

        /* init the hint as "no hint provided" */
        XADaddress(xp, 0);

        /* determine the starting extent offset of the page previous
         * to the page containing the offset.
         */
        prev = ((offset & ~POFFSET) >> JFS_SBI(sb)->l2bsize) - nbperpage;

        /* if the offsets in the first page of the file,
         * no hint provided.
         */
        if (prev < 0)
                return (0);

        /* prepare to lookup the previous page's extent info */
        lxdl.maxnlxd = 1;
        lxdl.nlxd = 1;
        lxdl.lxd = &lxd;
        LXDoffset(&lxd, prev)
            LXDlength(&lxd, nbperpage);

        xadl.maxnxad = 1;
        xadl.nxad = 0;
        xadl.xad = xp;

        /* perform the lookup */
        if ((rc = xtLookupList(ip, &lxdl, &xadl, 0)))
                return (rc);

        /* check if not extent exists for the previous page.  
         * this is possible for sparse files.
         */
        if (xadl.nxad == 0) {
//              assert(ISSPARSE(ip));
                return (0);
        }

        /* only preserve the abnr flag within the xad flags
         * of the returned hint.
         */
        xp->flag &= XAD_NOTRECORDED;

        if(xadl.nxad != 1 || lengthXAD(xp) != nbperpage) {          
                jfs_error(ip->i_sb, "extHint: corrupt xtree");
                return -EIO;
        }

        return (0);
}


/*
 * NAME:        extRecord()
 *
 * FUNCTION:    change a page with a file from not recorded to recorded.
 *
 * PARAMETERS:
 *      ip      - inode of the file.
 *      cp      - cbuf of the file page.
 *
 * RETURN VALUES:
 *      0       - success
 *      -EIO    - i/o error.
 *      -ENOSPC - insufficient disk resources.
 */
int extRecord(struct inode *ip, xad_t * xp)
{
        int rc;

        txBeginAnon(ip->i_sb);

        down(&JFS_IP(ip)->commit_sem);

        /* update the extent */
        rc = xtUpdate(0, ip, xp);

        up(&JFS_IP(ip)->commit_sem);
        return rc;
}


#ifdef _NOTYET
/*
 * NAME:        extFill()
 *
 * FUNCTION:    allocate disk space for a file page that represents
 *              a file hole.
 *
 * PARAMETERS:
 *      ip      - the inode of the file.
 *      cp      - cbuf of the file page represent the hole.
 *
 * RETURN VALUES:
 *      0       - success
 *      -EIO    - i/o error.
 *      -ENOSPC - insufficient disk resources.
 */
int extFill(struct inode *ip, xad_t * xp)
{
        int rc, nbperpage = JFS_SBI(ip->i_sb)->nbperpage;
        s64 blkno = offsetXAD(xp) >> ip->i_blksize;

//      assert(ISSPARSE(ip));

        /* initialize the extent allocation hint */
        XADaddress(xp, 0);

        /* allocate an extent to fill the hole */
        if ((rc = extAlloc(ip, nbperpage, blkno, xp, FALSE)))
                return (rc);

        assert(lengthPXD(xp) == nbperpage);

        return (0);
}
#endif                  /* _NOTYET */


/*
 * NAME:        extBalloc()
 *
 * FUNCTION:    allocate disk blocks to form an extent.
 *
 *              initially, we will try to allocate disk blocks for the
 *              requested size (nblocks).  if this fails (nblocks 
 *              contigious free blocks not avaliable), we'll try to allocate
 *              a smaller number of blocks (producing a smaller extent), with
 *              this smaller number of blocks consisting of the requested
 *              number of blocks rounded down to the next smaller power of 2
 *              number (i.e. 16 -> 8).  we'll continue to round down and
 *              retry the allocation until the number of blocks to allocate
 *              is smaller than the number of blocks per page.
 *              
 * PARAMETERS:
 *      ip       - the inode of the file.
 *      hint     - disk block number to be used as an allocation hint.
 *      *nblocks - pointer to an s64 value.  on entry, this value specifies
 *                 the desired number of block to be allocated. on successful
 *                 exit, this value is set to the number of blocks actually
 *                 allocated.
 *      blkno    - pointer to a block address that is filled in on successful
 *                 return with the starting block number of the newly 
 *                 allocated block range.
 *
 * RETURN VALUES:
 *      0       - success
 *      -EIO    - i/o error.
 *      -ENOSPC - insufficient disk resources.
 */
static int
extBalloc(struct inode *ip, s64 hint, s64 * nblocks, s64 * blkno)
{
        struct jfs_inode_info *ji = JFS_IP(ip);
        struct jfs_sb_info *sbi = JFS_SBI(ip->i_sb);
        s64 nb, nblks, daddr, max;
        int rc, nbperpage = sbi->nbperpage;
        struct bmap *bmp = sbi->bmap;
        int ag;

        /* get the number of blocks to initially attempt to allocate.
         * we'll first try the number of blocks requested unless this
         * number is greater than the maximum number of contigious free
         * blocks in the map. in that case, we'll start off with the 
         * maximum free.
         */
        max = (s64) 1 << bmp->db_maxfreebud;
        if (*nblocks >= max && *nblocks > nbperpage)
                nb = nblks = (max > nbperpage) ? max : nbperpage;
        else
                nb = nblks = *nblocks;

        /* try to allocate blocks */
        while ((rc = dbAlloc(ip, hint, nb, &daddr)) != 0) {
                /* if something other than an out of space error,
                 * stop and return this error.
                 */
                if (rc != -ENOSPC)
                        return (rc);

                /* decrease the allocation request size */
                nb = min(nblks, extRoundDown(nb));

                /* give up if we cannot cover a page */
                if (nb < nbperpage)
                        return (rc);
        }

        *nblocks = nb;
        *blkno = daddr;

        if (S_ISREG(ip->i_mode) && (ji->fileset == FILESYSTEM_I)) {
                ag = BLKTOAG(daddr, sbi);
                spin_lock_irq(&ji->ag_lock);
                if (ji->active_ag == -1) {
                        atomic_inc(&bmp->db_active[ag]);
                        ji->active_ag = ag;
                } else if (ji->active_ag != ag) {
                        atomic_dec(&bmp->db_active[ji->active_ag]);
                        atomic_inc(&bmp->db_active[ag]);
                        ji->active_ag = ag;
                }
                spin_unlock_irq(&ji->ag_lock);
        }

        return (0);
}


#ifdef _NOTYET
/*
 * NAME:        extBrealloc()
 *
 * FUNCTION:    attempt to extend an extent's allocation.
 *
 *              initially, we will try to extend the extent's allocation
 *              in place.  if this fails, we'll try to move the extent
 *              to a new set of blocks. if moving the extent, we initially
 *              will try to allocate disk blocks for the requested size
 *              (nnew).  if this fails  (nnew contigious free blocks not
 *              avaliable), we'll try  to allocate a smaller number of
 *              blocks (producing a smaller extent), with this smaller
 *              number of blocks consisting of the requested number of
 *              blocks rounded down to the next smaller power of 2
 *              number (i.e. 16 -> 8).  we'll continue to round down and
 *              retry the allocation until the number of blocks to allocate
 *              is smaller than the number of blocks per page.
 *              
 * PARAMETERS:
 *      ip       - the inode of the file.
 *      blkno    - starting block number of the extents current allocation.
 *      nblks    - number of blocks within the extents current allocation.
 *      newnblks - pointer to a s64 value.  on entry, this value is the
 *                 the new desired extent size (number of blocks).  on
 *                 successful exit, this value is set to the extent's actual
 *                 new size (new number of blocks).
 *      newblkno - the starting block number of the extents new allocation.
 *
 * RETURN VALUES:
 *      0       - success
 *      -EIO    - i/o error.
 *      -ENOSPC - insufficient disk resources.
 */
static int
extBrealloc(struct inode *ip,
            s64 blkno, s64 nblks, s64 * newnblks, s64 * newblkno)
{
        int rc;

        /* try to extend in place */
        if ((rc = dbExtend(ip, blkno, nblks, *newnblks - nblks)) == 0) {
                *newblkno = blkno;
                return (0);
        } else {
                if (rc != -ENOSPC)
                        return (rc);
        }

        /* in place extension not possible.  
         * try to move the extent to a new set of blocks.
         */
        return (extBalloc(ip, blkno, newnblks, newblkno));
}
#endif                  /* _NOTYET */


/*
 * NAME:        extRoundDown()
 *
 * FUNCTION:    round down a specified number of blocks to the next
 *              smallest power of 2 number.
 *
 * PARAMETERS:
 *      nb      - the inode of the file.
 *
 * RETURN VALUES:
 *      next smallest power of 2 number.
 */
static s64 extRoundDown(s64 nb)
{
        int i;
        u64 m, k;

        for (i = 0, m = (u64) 1 << 63; i < 64; i++, m >>= 1) {
                if (m & nb)
                        break;
        }

        i = 63 - i;
        k = (u64) 1 << i;
        k = ((k - 1) & nb) ? k : k >> 1;

        return (k);
}