コード例 #1
0
ファイル: fat32.c プロジェクト: narhen/OS
int fat_read(struct file_descriptor *fd, void *buffer, unsigned int n)
{
    struct fat_fd_meta *meta = fd->fs_info;
    int cluster_size = meta->prtinfo->bootrecord.spc, i, ret;
    char *bufptr = buffer, *clptr;

    if (meta->dir->attr == DENT_DIRECTORY)
        return -1;

    if (meta->cluster == NULL) {
        meta->cluster = kmalloc(meta->prtinfo->bootrecord.bps *
                meta->prtinfo->bootrecord.spc);
        cluster_read(meta->ccluster, meta->cluster, cluster_size, meta->prtinfo);
    }

    i = fd->filepos % (meta->prtinfo->bootrecord.bps *
            meta->prtinfo->bootrecord.spc);
    clptr = (char *)meta->cluster + i;
    for (ret = 0; ret < n && fd->filepos + i < meta->dir->size; ++i, ++ret) {
        if (i >= cluster_size * meta->prtinfo->bootrecord.bps) {
            meta->ccluster = next_cluster(meta->prtinfo->fat, meta->ccluster,
                    meta->prtinfo);
            if (meta->ccluster >= CLUSTER_END)
                return ret;
            cluster_read(meta->ccluster, meta->cluster, cluster_size,
                    meta->prtinfo);
            fd->filepos += i;
            clptr = meta->cluster;
            i = 0;
        }
        *bufptr++ = *clptr++;
    }
    fd->filepos += ret;
    return ret;
}
コード例 #2
0
ファイル: vnops.c プロジェクト: aredridel/mac9p
static int
vnop_read_9p(struct vnop_read_args *ap)
{
	node_9p *np;
	vnode_t vp;
	uio_t uio;
	int e;

	TRACE();
	vp = ap->a_vp;
	uio = ap->a_uio;
	np = NTO9P(vp);

	if (vnode_isdir(vp))
		return EISDIR;

	if (uio_offset(uio) < 0)
		return EINVAL;

	if (uio_resid(uio) == 0)
		return 0;

	nlock_9p(np, NODE_LCK_SHARED);
	if (vnode_isnocache(vp) || ISSET(ap->a_ioflag, IO_NOCACHE)) {
		if (ISSET(np->flags, NODE_MMAPPED))
			ubc_msync(vp, 0, ubc_getsize(vp), NULL, UBC_PUSHDIRTY|UBC_SYNC);
		else
			cluster_push(vp, IO_SYNC);
		ubc_msync(vp, uio_offset(uio), uio_offset(uio)+uio_resid(uio), NULL, UBC_INVALIDATE);
		e = nread_9p(np, uio);
	} else
		e = cluster_read(vp, uio, np->dir.length, ap->a_ioflag);
	nunlock_9p(np);
	return e;
}
コード例 #3
0
ファイル: fat_cluster_list.c プロジェクト: syuu1228/shiitake
fat_cluster_list_t *
fat_cluster_list_open(fat_instance_t * ins, cluster_t head,
		      int size)
{
	DPRINTF("ins:%p head:%u\n", ins, head);
	fat_cluster_list_t *list = fat_cluster_list_new(ins, size);
	if (!list)
		return list;
	cluster_t cluster_no = head;
	list->clusters[0] = head;
	if (!head)
		return list;
	DPRINTF("list->clusters[%x] = %x\n", 0, head);
	list->offset = 1;
	do
	{
		DPRINTF("offset:%d lendth:%d\n", list->offset, list->length);
		assert(list->offset < list->length);
		cluster_no = cluster_read(ins, cluster_no);
		assert(!IS_BAD_CLUSTER(cluster_no));
		list->clusters[list->offset++] = cluster_no;
		DPRINTF("list->clusters[%x] = %x\n", 
			list->offset - 1, cluster_no);
#ifdef DEBUG
		fat_cluster_list_dump(list);
#endif
	} while (!IS_END_OF_CLUSTER(cluster_no));
	list->end = list->offset;
	list->offset = 0;
	return list;
}
コード例 #4
0
ファイル: fat32.c プロジェクト: narhen/OS
int fat_lseek(struct file_descriptor *fd, int offset, int whence)
{
    struct fat_fd_meta *meta = fd->fs_info;
    int cluster_size = meta->prtinfo->bootrecord.spc, tmp;
    int sector_size = meta->prtinfo->bootrecord.bps, ncl;

    if (meta->dir->attr == DENT_DIRECTORY)
        return -1;

    switch (whence) {
        case _SEEK_SET:
            ncl = (meta->dir->cluster_hi << 16) | meta->dir->cluster_lo;
            tmp = fd->filepos + offset / (cluster_size * sector_size);
            if (offset >= cluster_size * sector_size) {
                ncl = follow_cluster_chain(meta->prtinfo->fat, ncl, tmp,
                        cluster_size, meta->prtinfo);
                if (ncl >= CLUSTER_END)
                    return -1;
                meta->ccluster = ncl;
                if (meta->cluster == NULL)
                    meta->cluster = kmalloc(cluster_size * sector_size);
                cluster_read(ncl, meta->cluster, cluster_size, meta->prtinfo);
            }
            fd->filepos = offset;
            break;
        case _SEEK_CUR:
            if (fd->filepos + offset >= cluster_size * sector_size) {
                ncl = meta->ccluster;
                tmp = fd->filepos + offset / (cluster_size * sector_size);
                ncl = follow_cluster_chain(meta->prtinfo->fat, ncl, tmp,
                        cluster_size, meta->prtinfo);
                if (ncl >= CLUSTER_END)
                    return -1;
                meta->ccluster = ncl;
                if (meta->cluster == NULL)
                    meta->cluster = kmalloc(cluster_size * sector_size);
                cluster_read(ncl, meta->cluster, cluster_size, meta->prtinfo);
                fd->filepos += offset;
            } else
                fd->filepos += offset;
            break;
        case _SEEK_END:
            break;
    }
    return 0;
}
コード例 #5
0
ファイル: fat32.c プロジェクト: narhen/OS
int fat_readdir(struct file_descriptor *fd, struct dir *d)
{
    struct fat_fd_meta *meta = fd->fs_info;
    int cluster_size = meta->prtinfo->bootrecord.spc;
    struct dirent *dir;

    if (meta->dir->attr != DENT_DIRECTORY)
        return -1;

    if (meta->cluster == NULL) {
        meta->cluster = kmalloc(meta->prtinfo->bootrecord.bps *
                meta->prtinfo->bootrecord.spc);
        cluster_read(meta->ccluster, meta->cluster, cluster_size, meta->prtinfo);
    }

    dir = meta->cluster;
    dir += fd->filepos;

    while (dir->attr == DENT_LONG || dir->attr == 0) {
        if ((fd->filepos * sizeof(struct dirent)) >= cluster_size * meta->prtinfo->bootrecord.bps) {
            meta->ccluster = next_cluster(meta->prtinfo->fat, meta->ccluster,
                    meta->prtinfo);
            if (meta->ccluster >= CLUSTER_END)
                return 0;
            cluster_read(meta->ccluster, meta->cluster, cluster_size,
                    meta->prtinfo);
            fd->filepos = 0;
        }
        ++dir;
        ++fd->filepos;
    }
    ++fd->filepos;
    get_filename(dir, d->filename);

    return 1;
}
コード例 #6
0
ファイル: fat32.c プロジェクト: narhen/OS
    static struct dirent *search_dir(char *name, struct fat_part_desc *desc,
        int start_cluster, int dircount, char *cl)
{
    struct dirent *dir;
    int current_cluster = start_cluster;

    while (current_cluster < CLUSTER_END) {
        cluster_read(current_cluster, cl, desc->bootrecord.spc, desc);
        dir = search_cluster(name, cl, dircount);
        if (dir == NULL) {
            current_cluster = next_cluster(desc->fat, current_cluster,
                    desc);
        } else
            return dir;
    }

    return NULL;
}
コード例 #7
0
ファイル: fat_cluster_list.c プロジェクト: syuu1228/shiitake
int 
fat_cluster_list_calculate_size_from_cluster_no(fat_instance_t * ins,
						cluster_t cluster_no)
{
	DPRINTF("ins:%p cluster_no:%u\n", ins, cluster_no);
	if (!cluster_no)
	{
		DPRINTF("return:0\n");
		return 0;
	}
	assert(!IS_END_OF_CLUSTER(cluster_no) && !IS_BAD_CLUSTER(cluster_no));
	int i = 1;
	do
	{
		cluster_no = cluster_read(ins, cluster_no);
		assert(!IS_BAD_CLUSTER(cluster_no));
		i++;
	} while (!IS_END_OF_CLUSTER(cluster_no));
	DPRINTF("return:%d\n", i);
	return i;
}
コード例 #8
0
/*
 * Vnode op for reading.
 */
static int
ext2_read(struct vop_read_args *ap)
{
	struct vnode *vp;
	struct inode *ip;
	struct uio *uio;
	struct m_ext2fs *fs;
	struct buf *bp;
	daddr_t lbn, nextlbn;
	off_t bytesinfile;
	long size, xfersize, blkoffset;
	int error, orig_resid, seqcount;
	int ioflag;

	vp = ap->a_vp;
	uio = ap->a_uio;
	ioflag = ap->a_ioflag;

	seqcount = ap->a_ioflag >> IO_SEQSHIFT;
	ip = VTOI(vp);

#ifdef INVARIANTS
	if (uio->uio_rw != UIO_READ)
		panic("%s: mode", "ext2_read");

	if (vp->v_type == VLNK) {
		if ((int)ip->i_size < vp->v_mount->mnt_maxsymlinklen)
			panic("%s: short symlink", "ext2_read");
	} else if (vp->v_type != VREG && vp->v_type != VDIR)
		panic("%s: type %d", "ext2_read", vp->v_type);
#endif
	orig_resid = uio->uio_resid;
	KASSERT(orig_resid >= 0, ("ext2_read: uio->uio_resid < 0"));
	if (orig_resid == 0)
		return (0);
	KASSERT(uio->uio_offset >= 0, ("ext2_read: uio->uio_offset < 0"));
	fs = ip->i_e2fs;
	if (uio->uio_offset < ip->i_size &&
	    uio->uio_offset >= fs->e2fs_maxfilesize)
	    	return (EOVERFLOW);

	for (error = 0, bp = NULL; uio->uio_resid > 0; bp = NULL) {
		if ((bytesinfile = ip->i_size - uio->uio_offset) <= 0)
			break;
		lbn = lblkno(fs, uio->uio_offset);
		nextlbn = lbn + 1;
		size = blksize(fs, ip, lbn);
		blkoffset = blkoff(fs, uio->uio_offset);

		xfersize = fs->e2fs_fsize - blkoffset;
		if (uio->uio_resid < xfersize)
			xfersize = uio->uio_resid;
		if (bytesinfile < xfersize)
			xfersize = bytesinfile;

		if (lblktosize(fs, nextlbn) >= ip->i_size)
			error = bread(vp, lbn, size, NOCRED, &bp);
		else if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
			error = cluster_read(vp, ip->i_size, lbn, size,
			    NOCRED, blkoffset + uio->uio_resid, seqcount,
			    0, &bp);
		} else if (seqcount > 1) {
			int nextsize = blksize(fs, ip, nextlbn);
			error = breadn(vp, lbn,
			    size, &nextlbn, &nextsize, 1, NOCRED, &bp);
		} else
			error = bread(vp, lbn, size, NOCRED, &bp);
		if (error) {
			brelse(bp);
			bp = NULL;
			break;
		}

		/*
		 * If IO_DIRECT then set B_DIRECT for the buffer.  This
		 * will cause us to attempt to release the buffer later on
		 * and will cause the buffer cache to attempt to free the
		 * underlying pages.
		 */
		if (ioflag & IO_DIRECT)
			bp->b_flags |= B_DIRECT;

		/*
		 * We should only get non-zero b_resid when an I/O error
		 * has occurred, which should cause us to break above.
		 * However, if the short read did not cause an error,
		 * then we want to ensure that we do not uiomove bad
		 * or uninitialized data.
		 */
		size -= bp->b_resid;
		if (size < xfersize) {
			if (size == 0)
				break;
			xfersize = size;
		}
		error = uiomove((char *)bp->b_data + blkoffset,
  			(int)xfersize, uio);
		if (error)
			break;

		if (ioflag & (IO_VMIO|IO_DIRECT)) {
			/*
			 * If it's VMIO or direct I/O, then we don't
			 * need the buf, mark it available for
			 * freeing. If it's non-direct VMIO, the VM has
			 * the data.
			 */
			bp->b_flags |= B_RELBUF;
			brelse(bp);
		} else {
			/*
			 * Otherwise let whoever
			 * made the request take care of
			 * freeing it. We just queue
			 * it onto another list.
			 */
			bqrelse(bp);
		}
	}

	/* 
	 * This can only happen in the case of an error
	 * because the loop above resets bp to NULL on each iteration
	 * and on normal completion has not set a new value into it.
	 * so it must have come from a 'break' statement
	 */
	if (bp != NULL) {
		if (ioflag & (IO_VMIO|IO_DIRECT)) {
			bp->b_flags |= B_RELBUF;
			brelse(bp);
		} else {
			bqrelse(bp);
		}
	}

	if ((error == 0 || uio->uio_resid != orig_resid) &&
	    (vp->v_mount->mnt_flag & MNT_NOATIME) == 0)
		ip->i_flag |= IN_ACCESS;
	return (error);
}
コード例 #9
0
ファイル: ext2_balloc.c プロジェクト: kwitaszczyk/freebsd
/*
 * Balloc defines the structure of filesystem storage
 * by allocating the physical blocks on a device given
 * the inode and the logical block number in a file.
 */
int
ext2_balloc(struct inode *ip, e2fs_lbn_t lbn, int size, struct ucred *cred,
    struct buf **bpp, int flags)
{
	struct m_ext2fs *fs;
	struct ext2mount *ump;
	struct buf *bp, *nbp;
	struct vnode *vp = ITOV(ip);
	struct indir indirs[NIADDR + 2];
	e4fs_daddr_t nb, newb;
	e2fs_daddr_t *bap, pref;
	int osize, nsize, num, i, error;

	*bpp = NULL;
	if (lbn < 0)
		return (EFBIG);
	fs = ip->i_e2fs;
	ump = ip->i_ump;

	/*
	 * check if this is a sequential block allocation. 
	 * If so, increment next_alloc fields to allow ext2_blkpref 
	 * to make a good guess
	 */
	if (lbn == ip->i_next_alloc_block + 1) {
		ip->i_next_alloc_block++;
		ip->i_next_alloc_goal++;
	}

	/*
	 * The first NDADDR blocks are direct blocks
	 */
	if (lbn < NDADDR) {
		nb = ip->i_db[lbn];
		/* no new block is to be allocated, and no need to expand
		   the file */
		if (nb != 0 && ip->i_size >= (lbn + 1) * fs->e2fs_bsize) {
			error = bread(vp, lbn, fs->e2fs_bsize, NOCRED, &bp);
			if (error) {
				brelse(bp);
				return (error);
			}
			bp->b_blkno = fsbtodb(fs, nb);
			*bpp = bp;
			return (0);
		}
		if (nb != 0) {
			/*
			 * Consider need to reallocate a fragment.
			 */
			osize = fragroundup(fs, blkoff(fs, ip->i_size));
			nsize = fragroundup(fs, size);
			if (nsize <= osize) {
				error = bread(vp, lbn, osize, NOCRED, &bp);
				if (error) {
					brelse(bp);
					return (error);
				}
				bp->b_blkno = fsbtodb(fs, nb);
			} else {
			/* Godmar thinks: this shouldn't happen w/o fragments */
				printf("nsize %d(%d) > osize %d(%d) nb %d\n", 
					(int)nsize, (int)size, (int)osize, 
					(int)ip->i_size, (int)nb);
				panic(
				    "ext2_balloc: Something is terribly wrong");
/*
 * please note there haven't been any changes from here on -
 * FFS seems to work.
 */
			}
		} else {
			if (ip->i_size < (lbn + 1) * fs->e2fs_bsize)
				nsize = fragroundup(fs, size);
			else
				nsize = fs->e2fs_bsize;
			EXT2_LOCK(ump);
			error = ext2_alloc(ip, lbn,
			    ext2_blkpref(ip, lbn, (int)lbn, &ip->i_db[0], 0),
			    nsize, cred, &newb);
			if (error)
				return (error);
			bp = getblk(vp, lbn, nsize, 0, 0, 0);
			bp->b_blkno = fsbtodb(fs, newb);
			if (flags & BA_CLRBUF)
				vfs_bio_clrbuf(bp);
		}
		ip->i_db[lbn] = dbtofsb(fs, bp->b_blkno);
		ip->i_flag |= IN_CHANGE | IN_UPDATE;
		*bpp = bp;
		return (0);
	}
	/*
	 * Determine the number of levels of indirection.
	 */
	pref = 0;
	if ((error = ext2_getlbns(vp, lbn, indirs, &num)) != 0)
		return (error);
#ifdef INVARIANTS
	if (num < 1)
		panic ("ext2_balloc: ext2_getlbns returned indirect block");
#endif
	/*
	 * Fetch the first indirect block allocating if necessary.
	 */
	--num;
	nb = ip->i_ib[indirs[0].in_off];
	if (nb == 0) {
		EXT2_LOCK(ump);
		pref = ext2_blkpref(ip, lbn, indirs[0].in_off + 
					     EXT2_NDIR_BLOCKS, &ip->i_db[0], 0);
		if ((error = ext2_alloc(ip, lbn, pref, fs->e2fs_bsize, cred,
			&newb)))
			return (error);
		nb = newb;
		bp = getblk(vp, indirs[1].in_lbn, fs->e2fs_bsize, 0, 0, 0);
		bp->b_blkno = fsbtodb(fs, newb);
		vfs_bio_clrbuf(bp);
		/*
		 * Write synchronously so that indirect blocks
		 * never point at garbage.
		 */
		if ((error = bwrite(bp)) != 0) {
			ext2_blkfree(ip, nb, fs->e2fs_bsize);
			return (error);
		}
		ip->i_ib[indirs[0].in_off] = newb;
		ip->i_flag |= IN_CHANGE | IN_UPDATE;
	}
	/*
	 * Fetch through the indirect blocks, allocating as necessary.
	 */
	for (i = 1;;) {
		error = bread(vp,
		    indirs[i].in_lbn, (int)fs->e2fs_bsize, NOCRED, &bp);
		if (error) {
			brelse(bp);
			return (error);
		}
		bap = (e2fs_daddr_t *)bp->b_data;
		nb = bap[indirs[i].in_off];
		if (i == num)
			break;
		i += 1;
		if (nb != 0) {
			bqrelse(bp);
			continue;
		}
		EXT2_LOCK(ump);
		if (pref == 0)
			pref = ext2_blkpref(ip, lbn, indirs[i].in_off, bap,
						bp->b_lblkno);
		error =  ext2_alloc(ip, lbn, pref, (int)fs->e2fs_bsize, cred, &newb);
		if (error) {
			brelse(bp);
			return (error);
		}
		nb = newb;
		nbp = getblk(vp, indirs[i].in_lbn, fs->e2fs_bsize, 0, 0, 0);
		nbp->b_blkno = fsbtodb(fs, nb);
		vfs_bio_clrbuf(nbp);
		/*
		 * Write synchronously so that indirect blocks
		 * never point at garbage.
		 */
		if ((error = bwrite(nbp)) != 0) {
			ext2_blkfree(ip, nb, fs->e2fs_bsize);
			EXT2_UNLOCK(ump);
			brelse(bp);
			return (error);
		}
		bap[indirs[i - 1].in_off] = nb;
		/*
		 * If required, write synchronously, otherwise use
		 * delayed write.
		 */
		if (flags & IO_SYNC) {
			bwrite(bp);
		} else {
			if (bp->b_bufsize == fs->e2fs_bsize)
				bp->b_flags |= B_CLUSTEROK;
			bdwrite(bp);
		}
	}
	/*
	 * Get the data block, allocating if necessary.
	 */
	if (nb == 0) {
		EXT2_LOCK(ump);
		pref = ext2_blkpref(ip, lbn, indirs[i].in_off, &bap[0], 
				bp->b_lblkno);
		if ((error = ext2_alloc(ip,
		    lbn, pref, (int)fs->e2fs_bsize, cred, &newb)) != 0) {
			brelse(bp);
			return (error);
		}
		nb = newb;
		nbp = getblk(vp, lbn, fs->e2fs_bsize, 0, 0, 0);
		nbp->b_blkno = fsbtodb(fs, nb);
		if (flags & BA_CLRBUF)
			vfs_bio_clrbuf(nbp);
		bap[indirs[i].in_off] = nb;
		/*
		 * If required, write synchronously, otherwise use
		 * delayed write.
		 */
		if (flags & IO_SYNC) {
			bwrite(bp);
		} else {
		if (bp->b_bufsize == fs->e2fs_bsize)
				bp->b_flags |= B_CLUSTEROK;
			bdwrite(bp);
		}
		*bpp = nbp;
		return (0);
	}
	brelse(bp);
	if (flags & BA_CLRBUF) {
		int seqcount = (flags & BA_SEQMASK) >> BA_SEQSHIFT;
		if (seqcount && (vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
			error = cluster_read(vp, ip->i_size, lbn,
			    (int)fs->e2fs_bsize, NOCRED,
			    MAXBSIZE, seqcount, 0, &nbp);
		} else {
			error = bread(vp, lbn, (int)fs->e2fs_bsize, NOCRED, &nbp);
		}
		if (error) {
			brelse(nbp);
			return (error);
		}
	} else {
コード例 #10
0
/*
 * ffs_balloc(struct vnode *a_vp, ufs_daddr_t a_lbn, int a_size,
 *	      struct ucred *a_cred, int a_flags, struct buf *a_bpp)
 *
 * Balloc defines the structure of filesystem storage by allocating
 * the physical blocks on a device given the inode and the logical
 * block number in a file.
 *
 * NOTE: B_CLRBUF - this flag tells balloc to clear invalid portions
 *	 of the buffer.  However, any dirty bits will override missing
 *	 valid bits.  This case occurs when writable mmaps are truncated
 *	 and then extended.
 */
int
ffs_balloc(struct vop_balloc_args *ap)
{
	struct inode *ip;
	ufs_daddr_t lbn;
	int size;
	struct ucred *cred;
	int flags;
	struct fs *fs;
	ufs_daddr_t nb;
	struct buf *bp, *nbp, *dbp;
	struct vnode *vp;
	struct indir indirs[NIADDR + 2];
	ufs_daddr_t newb, *bap, pref;
	int deallocated, osize, nsize, num, i, error;
	ufs_daddr_t *allocib, *blkp, *allocblk, allociblk[NIADDR + 1];
	ufs_daddr_t *lbns_remfree, lbns[NIADDR + 1];
	int unwindidx;
	int seqcount;

	vp = ap->a_vp;
	ip = VTOI(vp);
	fs = ip->i_fs;
	lbn = lblkno(fs, ap->a_startoffset);
	size = blkoff(fs, ap->a_startoffset) + ap->a_size;
	if (size > fs->fs_bsize)
		panic("ffs_balloc: blk too big");
	*ap->a_bpp = NULL;
	if (lbn < 0)
		return (EFBIG);
	cred = ap->a_cred;
	flags = ap->a_flags;

	/*
	 * The vnode must be locked for us to be able to safely mess
	 * around with the inode.
	 */
	if (vn_islocked(vp) != LK_EXCLUSIVE) {
		panic("ffs_balloc: vnode %p not exclusively locked!", vp);
	}

	/*
	 * If the next write will extend the file into a new block,
	 * and the file is currently composed of a fragment
	 * this fragment has to be extended to be a full block.
	 */
	nb = lblkno(fs, ip->i_size);
	if (nb < NDADDR && nb < lbn) {
		/*
		 * The filesize prior to this write can fit in direct
		 * blocks (ex. fragmentation is possibly done)
		 * we are now extending the file write beyond
		 * the block which has end of the file prior to this write.
		 */
		osize = blksize(fs, ip, nb);
		/*
		 * osize gives disk allocated size in the last block. It is
		 * either in fragments or a file system block size.
		 */
		if (osize < fs->fs_bsize && osize > 0) {
			/* A few fragments are already allocated, since the
			 * current extends beyond this block allocated the
			 * complete block as fragments are on in last block.
			 */
			error = ffs_realloccg(ip, nb,
				ffs_blkpref(ip, nb, (int)nb, &ip->i_db[0]),
				osize, (int)fs->fs_bsize, cred, &bp);
			if (error)
				return (error);
			if (DOINGSOFTDEP(vp))
				softdep_setup_allocdirect(ip, nb,
				    dofftofsb(fs, bp->b_bio2.bio_offset), 
				    ip->i_db[nb], fs->fs_bsize, osize, bp);
			/* adjust the inode size, we just grew */
			ip->i_size = smalllblktosize(fs, nb + 1);
			ip->i_db[nb] = dofftofsb(fs, bp->b_bio2.bio_offset);
			ip->i_flag |= IN_CHANGE | IN_UPDATE;
			if (flags & B_SYNC)
				bwrite(bp);
			else
				bawrite(bp);
			/* bp is already released here */
		}
	}
	/*
	 * The first NDADDR blocks are direct blocks
	 */
	if (lbn < NDADDR) {
		nb = ip->i_db[lbn];
		if (nb != 0 && ip->i_size >= smalllblktosize(fs, lbn + 1)) {
			error = bread(vp, lblktodoff(fs, lbn), fs->fs_bsize, &bp);
			if (error) {
				brelse(bp);
				return (error);
			}
			bp->b_bio2.bio_offset = fsbtodoff(fs, nb);
			*ap->a_bpp = bp;
			return (0);
		}
		if (nb != 0) {
			/*
			 * Consider need to reallocate a fragment.
			 */
			osize = fragroundup(fs, blkoff(fs, ip->i_size));
			nsize = fragroundup(fs, size);
			if (nsize <= osize) {
				error = bread(vp, lblktodoff(fs, lbn), 
					      osize, &bp);
				if (error) {
					brelse(bp);
					return (error);
				}
				bp->b_bio2.bio_offset = fsbtodoff(fs, nb);
			} else {
				/*
				 * NOTE: ffs_realloccg() issues a bread().
				 */
				error = ffs_realloccg(ip, lbn,
				    ffs_blkpref(ip, lbn, (int)lbn,
					&ip->i_db[0]), osize, nsize, cred, &bp);
				if (error)
					return (error);
				if (DOINGSOFTDEP(vp))
					softdep_setup_allocdirect(ip, lbn,
					    dofftofsb(fs, bp->b_bio2.bio_offset),
					    nb, nsize, osize, bp);
			}
		} else {
			if (ip->i_size < smalllblktosize(fs, lbn + 1))
				nsize = fragroundup(fs, size);
			else
				nsize = fs->fs_bsize;
			error = ffs_alloc(ip, lbn,
			    ffs_blkpref(ip, lbn, (int)lbn, &ip->i_db[0]),
			    nsize, cred, &newb);
			if (error)
				return (error);
			bp = getblk(vp, lblktodoff(fs, lbn), nsize, 0, 0);
			bp->b_bio2.bio_offset = fsbtodoff(fs, newb);
			if (flags & B_CLRBUF)
				vfs_bio_clrbuf(bp);
			if (DOINGSOFTDEP(vp))
				softdep_setup_allocdirect(ip, lbn, newb, 0,
				    nsize, 0, bp);
		}
		ip->i_db[lbn] = dofftofsb(fs, bp->b_bio2.bio_offset);
		ip->i_flag |= IN_CHANGE | IN_UPDATE;
		*ap->a_bpp = bp;
		return (0);
	}
	/*
	 * Determine the number of levels of indirection.
	 */
	pref = 0;
	if ((error = ufs_getlbns(vp, lbn, indirs, &num)) != 0)
		return(error);
#ifdef DIAGNOSTIC
	if (num < 1)
		panic ("ffs_balloc: ufs_bmaparray returned indirect block");
#endif
	/*
	 * Get a handle on the data block buffer before working through 
	 * indirect blocks to avoid a deadlock between the VM system holding
	 * a locked VM page and issuing a BMAP (which tries to lock the
	 * indirect blocks), and the filesystem holding a locked indirect
	 * block and then trying to read a data block (which tries to lock
	 * the underlying VM pages).
	 */
	dbp = getblk(vp, lblktodoff(fs, lbn), fs->fs_bsize, 0, 0);

	/*
	 * Setup undo history
	 */
	allocib = NULL;
	allocblk = allociblk;
	lbns_remfree = lbns;

	unwindidx = -1;

	/*
	 * Fetch the first indirect block directly from the inode, allocating
	 * one if necessary. 
	 */
	--num;
	nb = ip->i_ib[indirs[0].in_off];
	if (nb == 0) {
		pref = ffs_blkpref(ip, lbn, 0, NULL);
		/*
		 * If the filesystem has run out of space we can skip the
		 * full fsync/undo of the main [fail] case since no undo
		 * history has been built yet.  Hence the goto fail2.
		 */
	        if ((error = ffs_alloc(ip, lbn, pref, (int)fs->fs_bsize,
		    cred, &newb)) != 0)
			goto fail2;
		nb = newb;
		*allocblk++ = nb;
		*lbns_remfree++ = indirs[1].in_lbn;
		bp = getblk(vp, lblktodoff(fs, indirs[1].in_lbn),
			    fs->fs_bsize, 0, 0);
		bp->b_bio2.bio_offset = fsbtodoff(fs, nb);
		vfs_bio_clrbuf(bp);
		if (DOINGSOFTDEP(vp)) {
			softdep_setup_allocdirect(ip, NDADDR + indirs[0].in_off,
			    newb, 0, fs->fs_bsize, 0, bp);
			bdwrite(bp);
		} else {
			/*
			 * Write synchronously so that indirect blocks
			 * never point at garbage.
			 */
			if (DOINGASYNC(vp))
				bdwrite(bp);
			else if ((error = bwrite(bp)) != 0)
				goto fail;
		}
		allocib = &ip->i_ib[indirs[0].in_off];
		*allocib = nb;
		ip->i_flag |= IN_CHANGE | IN_UPDATE;
	}

	/*
	 * Fetch through the indirect blocks, allocating as necessary.
	 */
	for (i = 1;;) {
		error = bread(vp, lblktodoff(fs, indirs[i].in_lbn), (int)fs->fs_bsize, &bp);
		if (error) {
			brelse(bp);
			goto fail;
		}
		bap = (ufs_daddr_t *)bp->b_data;
		nb = bap[indirs[i].in_off];
		if (i == num)
			break;
		i += 1;
		if (nb != 0) {
			bqrelse(bp);
			continue;
		}
		if (pref == 0)
			pref = ffs_blkpref(ip, lbn, 0, NULL);
		if ((error =
		    ffs_alloc(ip, lbn, pref, (int)fs->fs_bsize, cred, &newb)) != 0) {
			brelse(bp);
			goto fail;
		}
		nb = newb;
		*allocblk++ = nb;
		*lbns_remfree++ = indirs[i].in_lbn;
		nbp = getblk(vp, lblktodoff(fs, indirs[i].in_lbn),
			     fs->fs_bsize, 0, 0);
		nbp->b_bio2.bio_offset = fsbtodoff(fs, nb);
		vfs_bio_clrbuf(nbp);
		if (DOINGSOFTDEP(vp)) {
			softdep_setup_allocindir_meta(nbp, ip, bp,
			    indirs[i - 1].in_off, nb);
			bdwrite(nbp);
		} else {
			/*
			 * Write synchronously so that indirect blocks
			 * never point at garbage.
			 */
			if ((error = bwrite(nbp)) != 0) {
				brelse(bp);
				goto fail;
			}
		}
		bap[indirs[i - 1].in_off] = nb;
		if (allocib == NULL && unwindidx < 0)
			unwindidx = i - 1;
		/*
		 * If required, write synchronously, otherwise use
		 * delayed write.
		 */
		if (flags & B_SYNC) {
			bwrite(bp);
		} else {
			if (bp->b_bufsize == fs->fs_bsize)
				bp->b_flags |= B_CLUSTEROK;
			bdwrite(bp);
		}
	}

	/*
	 * Get the data block, allocating if necessary.  We have already
	 * called getblk() on the data block buffer, dbp.  If we have to
	 * allocate it and B_CLRBUF has been set the inference is an intention
	 * to zero out the related disk blocks, so we do not have to issue
	 * a read.  Instead we simply call vfs_bio_clrbuf().  If B_CLRBUF is
	 * not set the caller intends to overwrite the entire contents of the
	 * buffer and we don't waste time trying to clean up the contents.
	 *
	 * bp references the current indirect block.  When allocating, 
	 * the block must be updated.
	 */
	if (nb == 0) {
		pref = ffs_blkpref(ip, lbn, indirs[i].in_off, &bap[0]);
		error = ffs_alloc(ip,
		    lbn, pref, (int)fs->fs_bsize, cred, &newb);
		if (error) {
			brelse(bp);
			goto fail;
		}
		nb = newb;
		*allocblk++ = nb;
		*lbns_remfree++ = lbn;
		dbp->b_bio2.bio_offset = fsbtodoff(fs, nb);
		if (flags & B_CLRBUF)
			vfs_bio_clrbuf(dbp);
		if (DOINGSOFTDEP(vp))
			softdep_setup_allocindir_page(ip, lbn, bp,
			    indirs[i].in_off, nb, 0, dbp);
		bap[indirs[i].in_off] = nb;
		/*
		 * If required, write synchronously, otherwise use
		 * delayed write.
		 */
		if (flags & B_SYNC) {
			bwrite(bp);
		} else {
			if (bp->b_bufsize == fs->fs_bsize)
				bp->b_flags |= B_CLUSTEROK;
			bdwrite(bp);
		}
		*ap->a_bpp = dbp;
		return (0);
	}
	brelse(bp);

	/*
	 * At this point all related indirect blocks have been allocated
	 * if necessary and released.  bp is no longer valid.  dbp holds
	 * our getblk()'d data block.
	 *
	 * XXX we previously performed a cluster_read operation here.
	 */
	if (flags & B_CLRBUF) {
		/*
		 * If B_CLRBUF is set we must validate the invalid portions
		 * of the buffer.  This typically requires a read-before-
		 * write.  The strategy call will fill in bio_offset in that
		 * case.
		 *
		 * If we hit this case we do a cluster read if possible
		 * since nearby data blocks are likely to be accessed soon
		 * too.
		 */
		if ((dbp->b_flags & B_CACHE) == 0) {
			bqrelse(dbp);
			seqcount = (flags & B_SEQMASK) >> B_SEQSHIFT;
			if (seqcount &&
			    (vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
				error = cluster_read(vp, (off_t)ip->i_size,
					    lblktodoff(fs, lbn),
					    (int)fs->fs_bsize, 
					    fs->fs_bsize,
					    seqcount * BKVASIZE,
					    &dbp);
			} else {
				error = bread(vp, lblktodoff(fs, lbn),
					      (int)fs->fs_bsize, &dbp);
			}
			if (error)
				goto fail;
		} else {
コード例 #11
0
ファイル: ffs_balloc.c プロジェクト: AhmadTux/freebsd
/*
 * Balloc defines the structure of filesystem storage
 * by allocating the physical blocks on a device given
 * the inode and the logical block number in a file.
 * This is the allocation strategy for UFS1. Below is
 * the allocation strategy for UFS2.
 */
int
ffs_balloc_ufs1(struct vnode *vp, off_t startoffset, int size,
    struct ucred *cred, int flags, struct buf **bpp)
{
	struct inode *ip;
	struct ufs1_dinode *dp;
	ufs_lbn_t lbn, lastlbn;
	struct fs *fs;
	ufs1_daddr_t nb;
	struct buf *bp, *nbp;
	struct ufsmount *ump;
	struct indir indirs[NIADDR + 2];
	int deallocated, osize, nsize, num, i, error;
	ufs2_daddr_t newb;
	ufs1_daddr_t *bap, pref;
	ufs1_daddr_t *allocib, *blkp, *allocblk, allociblk[NIADDR + 1];
	ufs2_daddr_t *lbns_remfree, lbns[NIADDR + 1];
	int unwindidx = -1;
	int saved_inbdflush;
	static struct timeval lastfail;
	static int curfail;
	int reclaimed;

	ip = VTOI(vp);
	dp = ip->i_din1;
	fs = ip->i_fs;
	ump = ip->i_ump;
	lbn = lblkno(fs, startoffset);
	size = blkoff(fs, startoffset) + size;
	reclaimed = 0;
	if (size > fs->fs_bsize)
		panic("ffs_balloc_ufs1: blk too big");
	*bpp = NULL;
	if (flags & IO_EXT)
		return (EOPNOTSUPP);
	if (lbn < 0)
		return (EFBIG);

	if (DOINGSOFTDEP(vp))
		softdep_prealloc(vp, MNT_WAIT);
	/*
	 * If the next write will extend the file into a new block,
	 * and the file is currently composed of a fragment
	 * this fragment has to be extended to be a full block.
	 */
	lastlbn = lblkno(fs, ip->i_size);
	if (lastlbn < NDADDR && lastlbn < lbn) {
		nb = lastlbn;
		osize = blksize(fs, ip, nb);
		if (osize < fs->fs_bsize && osize > 0) {
			UFS_LOCK(ump);
			error = ffs_realloccg(ip, nb, dp->di_db[nb],
			   ffs_blkpref_ufs1(ip, lastlbn, (int)nb,
			   &dp->di_db[0]), osize, (int)fs->fs_bsize, flags,
			   cred, &bp);
			if (error)
				return (error);
			if (DOINGSOFTDEP(vp))
				softdep_setup_allocdirect(ip, nb,
				    dbtofsb(fs, bp->b_blkno), dp->di_db[nb],
				    fs->fs_bsize, osize, bp);
			ip->i_size = smalllblktosize(fs, nb + 1);
			dp->di_size = ip->i_size;
			dp->di_db[nb] = dbtofsb(fs, bp->b_blkno);
			ip->i_flag |= IN_CHANGE | IN_UPDATE;
			if (flags & IO_SYNC)
				bwrite(bp);
			else
				bawrite(bp);
		}
	}
	/*
	 * The first NDADDR blocks are direct blocks
	 */
	if (lbn < NDADDR) {
		if (flags & BA_METAONLY)
			panic("ffs_balloc_ufs1: BA_METAONLY for direct block");
		nb = dp->di_db[lbn];
		if (nb != 0 && ip->i_size >= smalllblktosize(fs, lbn + 1)) {
			error = bread(vp, lbn, fs->fs_bsize, NOCRED, &bp);
			if (error) {
				brelse(bp);
				return (error);
			}
			bp->b_blkno = fsbtodb(fs, nb);
			*bpp = bp;
			return (0);
		}
		if (nb != 0) {
			/*
			 * Consider need to reallocate a fragment.
			 */
			osize = fragroundup(fs, blkoff(fs, ip->i_size));
			nsize = fragroundup(fs, size);
			if (nsize <= osize) {
				error = bread(vp, lbn, osize, NOCRED, &bp);
				if (error) {
					brelse(bp);
					return (error);
				}
				bp->b_blkno = fsbtodb(fs, nb);
			} else {
				UFS_LOCK(ump);
				error = ffs_realloccg(ip, lbn, dp->di_db[lbn],
				    ffs_blkpref_ufs1(ip, lbn, (int)lbn,
				    &dp->di_db[0]), osize, nsize, flags,
				    cred, &bp);
				if (error)
					return (error);
				if (DOINGSOFTDEP(vp))
					softdep_setup_allocdirect(ip, lbn,
					    dbtofsb(fs, bp->b_blkno), nb,
					    nsize, osize, bp);
			}
		} else {
			if (ip->i_size < smalllblktosize(fs, lbn + 1))
				nsize = fragroundup(fs, size);
			else
				nsize = fs->fs_bsize;
			UFS_LOCK(ump);
			error = ffs_alloc(ip, lbn,
			    ffs_blkpref_ufs1(ip, lbn, (int)lbn, &dp->di_db[0]),
			    nsize, flags, cred, &newb);
			if (error)
				return (error);
			bp = getblk(vp, lbn, nsize, 0, 0, 0);
			bp->b_blkno = fsbtodb(fs, newb);
			if (flags & BA_CLRBUF)
				vfs_bio_clrbuf(bp);
			if (DOINGSOFTDEP(vp))
				softdep_setup_allocdirect(ip, lbn, newb, 0,
				    nsize, 0, bp);
		}
		dp->di_db[lbn] = dbtofsb(fs, bp->b_blkno);
		ip->i_flag |= IN_CHANGE | IN_UPDATE;
		*bpp = bp;
		return (0);
	}
	/*
	 * Determine the number of levels of indirection.
	 */
	pref = 0;
	if ((error = ufs_getlbns(vp, lbn, indirs, &num)) != 0)
		return(error);
#ifdef INVARIANTS
	if (num < 1)
		panic ("ffs_balloc_ufs1: ufs_getlbns returned indirect block");
#endif
	saved_inbdflush = curthread_pflags_set(TDP_INBDFLUSH);
	/*
	 * Fetch the first indirect block allocating if necessary.
	 */
	--num;
	nb = dp->di_ib[indirs[0].in_off];
	allocib = NULL;
	allocblk = allociblk;
	lbns_remfree = lbns;
	if (nb == 0) {
		UFS_LOCK(ump);
		pref = ffs_blkpref_ufs1(ip, lbn, 0, (ufs1_daddr_t *)0);
	        if ((error = ffs_alloc(ip, lbn, pref, (int)fs->fs_bsize,
		    flags, cred, &newb)) != 0) {
			curthread_pflags_restore(saved_inbdflush);
			return (error);
		}
		nb = newb;
		*allocblk++ = nb;
		*lbns_remfree++ = indirs[1].in_lbn;
		bp = getblk(vp, indirs[1].in_lbn, fs->fs_bsize, 0, 0, 0);
		bp->b_blkno = fsbtodb(fs, nb);
		vfs_bio_clrbuf(bp);
		if (DOINGSOFTDEP(vp)) {
			softdep_setup_allocdirect(ip, NDADDR + indirs[0].in_off,
			    newb, 0, fs->fs_bsize, 0, bp);
			bdwrite(bp);
		} else {
			/*
			 * Write synchronously so that indirect blocks
			 * never point at garbage.
			 */
			if (DOINGASYNC(vp))
				bdwrite(bp);
			else if ((error = bwrite(bp)) != 0)
				goto fail;
		}
		allocib = &dp->di_ib[indirs[0].in_off];
		*allocib = nb;
		ip->i_flag |= IN_CHANGE | IN_UPDATE;
	}
	/*
	 * Fetch through the indirect blocks, allocating as necessary.
	 */
retry:
	for (i = 1;;) {
		error = bread(vp,
		    indirs[i].in_lbn, (int)fs->fs_bsize, NOCRED, &bp);
		if (error) {
			brelse(bp);
			goto fail;
		}
		bap = (ufs1_daddr_t *)bp->b_data;
		nb = bap[indirs[i].in_off];
		if (i == num)
			break;
		i += 1;
		if (nb != 0) {
			bqrelse(bp);
			continue;
		}
		UFS_LOCK(ump);
		if (pref == 0)
			pref = ffs_blkpref_ufs1(ip, lbn, 0, (ufs1_daddr_t *)0);
		if ((error = ffs_alloc(ip, lbn, pref, (int)fs->fs_bsize,
		    flags | IO_BUFLOCKED, cred, &newb)) != 0) {
			brelse(bp);
			if (++reclaimed == 1) {
				UFS_LOCK(ump);
				softdep_request_cleanup(fs, vp, cred,
				    FLUSH_BLOCKS_WAIT);
				UFS_UNLOCK(ump);
				goto retry;
			}
			if (ppsratecheck(&lastfail, &curfail, 1)) {
				ffs_fserr(fs, ip->i_number, "filesystem full");
				uprintf("\n%s: write failed, filesystem "
				    "is full\n", fs->fs_fsmnt);
			}
			goto fail;
		}
		nb = newb;
		*allocblk++ = nb;
		*lbns_remfree++ = indirs[i].in_lbn;
		nbp = getblk(vp, indirs[i].in_lbn, fs->fs_bsize, 0, 0, 0);
		nbp->b_blkno = fsbtodb(fs, nb);
		vfs_bio_clrbuf(nbp);
		if (DOINGSOFTDEP(vp)) {
			softdep_setup_allocindir_meta(nbp, ip, bp,
			    indirs[i - 1].in_off, nb);
			bdwrite(nbp);
		} else {
			/*
			 * Write synchronously so that indirect blocks
			 * never point at garbage.
			 */
			if ((error = bwrite(nbp)) != 0) {
				brelse(bp);
				goto fail;
			}
		}
		bap[indirs[i - 1].in_off] = nb;
		if (allocib == NULL && unwindidx < 0)
			unwindidx = i - 1;
		/*
		 * If required, write synchronously, otherwise use
		 * delayed write.
		 */
		if (flags & IO_SYNC) {
			bwrite(bp);
		} else {
			if (bp->b_bufsize == fs->fs_bsize)
				bp->b_flags |= B_CLUSTEROK;
			bdwrite(bp);
		}
	}
	/*
	 * If asked only for the indirect block, then return it.
	 */
	if (flags & BA_METAONLY) {
		curthread_pflags_restore(saved_inbdflush);
		*bpp = bp;
		return (0);
	}
	/*
	 * Get the data block, allocating if necessary.
	 */
	if (nb == 0) {
		UFS_LOCK(ump);
		pref = ffs_blkpref_ufs1(ip, lbn, indirs[i].in_off, &bap[0]);
		error = ffs_alloc(ip, lbn, pref, (int)fs->fs_bsize,
		    flags | IO_BUFLOCKED, cred, &newb);
		if (error) {
			brelse(bp);
			if (++reclaimed == 1) {
				UFS_LOCK(ump);
				softdep_request_cleanup(fs, vp, cred,
				    FLUSH_BLOCKS_WAIT);
				UFS_UNLOCK(ump);
				goto retry;
			}
			if (ppsratecheck(&lastfail, &curfail, 1)) {
				ffs_fserr(fs, ip->i_number, "filesystem full");
				uprintf("\n%s: write failed, filesystem "
				    "is full\n", fs->fs_fsmnt);
			}
			goto fail;
		}
		nb = newb;
		*allocblk++ = nb;
		*lbns_remfree++ = lbn;
		nbp = getblk(vp, lbn, fs->fs_bsize, 0, 0, 0);
		nbp->b_blkno = fsbtodb(fs, nb);
		if (flags & BA_CLRBUF)
			vfs_bio_clrbuf(nbp);
		if (DOINGSOFTDEP(vp))
			softdep_setup_allocindir_page(ip, lbn, bp,
			    indirs[i].in_off, nb, 0, nbp);
		bap[indirs[i].in_off] = nb;
		/*
		 * If required, write synchronously, otherwise use
		 * delayed write.
		 */
		if (flags & IO_SYNC) {
			bwrite(bp);
		} else {
			if (bp->b_bufsize == fs->fs_bsize)
				bp->b_flags |= B_CLUSTEROK;
			bdwrite(bp);
		}
		curthread_pflags_restore(saved_inbdflush);
		*bpp = nbp;
		return (0);
	}
	brelse(bp);
	if (flags & BA_CLRBUF) {
		int seqcount = (flags & BA_SEQMASK) >> BA_SEQSHIFT;
		if (seqcount && (vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
			error = cluster_read(vp, ip->i_size, lbn,
			    (int)fs->fs_bsize, NOCRED,
			    MAXBSIZE, seqcount, &nbp);
		} else {
			error = bread(vp, lbn, (int)fs->fs_bsize, NOCRED, &nbp);
		}
		if (error) {
			brelse(nbp);
			goto fail;
		}
	} else {
コード例 #12
0
ファイル: ffs_subr.c プロジェクト: Gwenio/DragonFlyBSD
/*
 * Return buffer with the contents of block "offset" from the beginning of
 * vnode "vp".  If "res" is non-zero, fill it in with a pointer to the
 * remaining space in the vnode.
 *
 * This version includes a read-ahead optimization.
 */
int
ffs_blkatoff_ra(struct vnode *vp, off_t uoffset, char **res, struct buf **bpp,
		int seqcount)
{
	struct inode *ip;
	struct fs *fs;
	struct buf *bp;
	ufs_daddr_t lbn;
	ufs_daddr_t nextlbn;
	off_t base_loffset;
	off_t next_loffset;
	int bsize, error;
	int nextbsize;

	ip = VTOI(vp);
	fs = ip->i_fs;
	lbn = lblkno(fs, uoffset);
	base_loffset = lblktodoff(fs, lbn);
	bsize = blksize(fs, ip, lbn);

	nextlbn = lbn + 1;
	next_loffset = lblktodoff(fs, nextlbn);


	*bpp = NULL;

	if (next_loffset >= ip->i_size) {
		/*
		 * Do not do readahead if this is the last block,
		 * bsize might represent a fragment.
		 */
		error = bread(vp, base_loffset, bsize, &bp);
	} else if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
		/*
		 * Try to cluster if we allowed to.
		 */
		error = cluster_read(vp, (off_t)ip->i_size,
				     base_loffset, bsize,
				     bsize, seqcount * BKVASIZE, &bp);
	} else if (seqcount > 1) {
		/*
		 * Faked read ahead
		 */
		nextbsize = blksize(fs, ip, nextlbn);
		error = breadn(vp, base_loffset, bsize,
			       &next_loffset, &nextbsize, 1, &bp);
	} else {
		/*
		 * Failing all of the above, just read what the
		 * user asked for. Interestingly, the same as
		 * the first option above.
		 */
		error = bread(vp, base_loffset, bsize, &bp);
	}
	if (error) {
		brelse(bp);
		return (error);
	}
	if (res)
		*res = (char *)bp->b_data + (int)(uoffset - base_loffset);
	*bpp = bp;
	return (0);
}
コード例 #13
0
int
xfs_read_file(xfs_mount_t *mp, xfs_inode_t *ip, struct uio *uio, int ioflag)
{
	xfs_fileoff_t lbn, nextlbn;
	xfs_fsize_t bytesinfile;
	long size, xfersize, blkoffset;
	struct buf *bp;
	struct vnode *vp;
	int error, orig_resid;
	int seqcount;

	seqcount = ioflag >> IO_SEQSHIFT;

	orig_resid = uio->uio_resid;
	if (orig_resid <= 0)
		return (0);

	vp = XFS_ITOV(ip)->v_vnode;

	/*
	 * Ok so we couldn't do it all in one vm trick...
	 * so cycle around trying smaller bites..
	 */
	for (error = 0, bp = NULL; uio->uio_resid > 0; bp = NULL) {
		if ((bytesinfile = ip->i_d.di_size - uio->uio_offset) <= 0)
			break;

		lbn = XFS_B_TO_FSBT(mp, uio->uio_offset);
		nextlbn = lbn + 1;

		/*
		 * size of buffer.  The buffer representing the
		 * end of the file is rounded up to the size of
		 * the block type ( fragment or full block,
		 * depending ).
		 */
		size = mp->m_sb.sb_blocksize;
		blkoffset = XFS_B_FSB_OFFSET(mp, uio->uio_offset);

		/*
		 * The amount we want to transfer in this iteration is
		 * one FS block less the amount of the data before
		 * our startpoint (duh!)
		 */
		xfersize = mp->m_sb.sb_blocksize - blkoffset;

		/*
		 * But if we actually want less than the block,
		 * or the file doesn't have a whole block more of data,
		 * then use the lesser number.
		 */
		if (uio->uio_resid < xfersize)
			xfersize = uio->uio_resid;
		if (bytesinfile < xfersize)
			xfersize = bytesinfile;

		if (XFS_FSB_TO_B(mp, nextlbn) >= ip->i_d.di_size ) {
			/*
			 * Don't do readahead if this is the end of the file.
			 */
			error = bread(vp, lbn, size, NOCRED, &bp);
		} else if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
			/*
			 * Otherwise if we are allowed to cluster,
			 * grab as much as we can.
			 *
			 * XXX  This may not be a win if we are not
			 * doing sequential access.
			 */
			error = cluster_read(vp, ip->i_d.di_size, lbn,
				size, NOCRED, uio->uio_resid, seqcount, &bp);
		} else if (seqcount > 1) {
			/*
			 * If we are NOT allowed to cluster, then
			 * if we appear to be acting sequentially,
			 * fire off a request for a readahead
			 * as well as a read. Note that the 4th and 5th
			 * arguments point to arrays of the size specified in
			 * the 6th argument.
			 */
			int nextsize = mp->m_sb.sb_blocksize;
			error = breadn(vp, lbn,
			    size, &nextlbn, &nextsize, 1, NOCRED, &bp);
		} else {
			/*
			 * Failing all of the above, just read what the
			 * user asked for. Interestingly, the same as
			 * the first option above.
			 */
			error = bread(vp, lbn, size, NOCRED, &bp);
		}
		if (error) {
			brelse(bp);
			bp = NULL;
			break;
		}

		/*
		 * If IO_DIRECT then set B_DIRECT for the buffer.  This
		 * will cause us to attempt to release the buffer later on
		 * and will cause the buffer cache to attempt to free the
		 * underlying pages.
		 */
		if (ioflag & IO_DIRECT)
			bp->b_flags |= B_DIRECT;

		/*
		 * We should only get non-zero b_resid when an I/O error
		 * has occurred, which should cause us to break above.
		 * However, if the short read did not cause an error,
		 * then we want to ensure that we do not uiomove bad
		 * or uninitialized data.
		 */
		size -= bp->b_resid;
		if (size < xfersize) {
			if (size == 0)
				break;
			xfersize = size;
		}

		/*
		 * otherwise use the general form
		 */
		error = uiomove((char *)bp->b_data + blkoffset,
			    (int)xfersize, uio);

		if (error)
			break;

		if (ioflag & (IO_VMIO|IO_DIRECT) ) {
			/*
			 * If there are no dependencies, and it's VMIO,
			 * then we don't need the buf, mark it available
			 * for freeing. The VM has the data.
			 */
			bp->b_flags |= B_RELBUF;
			brelse(bp);
		} else {
			/*
			 * Otherwise let whoever
			 * made the request take care of
			 * freeing it. We just queue
			 * it onto another list.
			 */
			bqrelse(bp);
		}
	}

	/*
	 * This can only happen in the case of an error
	 * because the loop above resets bp to NULL on each iteration
	 * and on normal completion has not set a new value into it.
	 * so it must have come from a 'break' statement
	 */
	if (bp != NULL) {
		if (ioflag & (IO_VMIO|IO_DIRECT)) {
			bp->b_flags |= B_RELBUF;
			brelse(bp);
		} else
			bqrelse(bp);
	}

	return (error);
}
コード例 #14
0
ファイル: ffs_balloc.c プロジェクト: dancrossnyc/harvey
/*
 * Balloc defines the structure of file system storage
 * by allocating the physical blocks on a device given
 * the inode and the logical block number in a file.
 * This is the allocation strategy for UFS2. Above is
 * the allocation strategy for UFS1.
 */
int
ffs_balloc_ufs2(vnode *vp, off_t startoffset, int size,
    Ucred *cred, int flags, Buf **bpp)
{
	int error = 0;
	print("HARVEY TODO: %s\n", __func__);
#if 0
	struct inode *ip;
	struct ufs2_dinode *dp;
	ufs_lbn_t lbn, lastlbn;
	struct fs *fs;
	struct buf *bp, *nbp;
	struct ufsmount *ump;
	struct indir indirs[UFS_NIADDR + 2];
	ufs2_daddr_t nb, newb, *bap, pref;
	ufs2_daddr_t *allocib, *blkp, *allocblk, allociblk[UFS_NIADDR + 1];
	ufs2_daddr_t *lbns_remfree, lbns[UFS_NIADDR + 1];
	int deallocated, osize, nsize, num, i, error;
	int unwindidx = -1;
	int saved_inbdflush;
	static struct timeval lastfail;
	static int curfail;
	int gbflags, reclaimed;

	ip = VTOI(vp);
	dp = ip->i_din2;
	fs = ITOFS(ip);
	ump = ITOUMP(ip);
	lbn = lblkno(fs, startoffset);
	size = blkoff(fs, startoffset) + size;
	reclaimed = 0;
	if (size > fs->fs_bsize)
		panic("ffs_balloc_ufs2: blk too big");
	*bpp = nil;
	if (lbn < 0)
		return (EFBIG);
	gbflags = (flags & BA_UNMAPPED) != 0 ? GB_UNMAPPED : 0;

	if (DOINGSOFTDEP(vp))
		softdep_prealloc(vp, MNT_WAIT);
	
	/*
	 * Check for allocating external data.
	 */
	if (flags & IO_EXT) {
		if (lbn >= UFS_NXADDR)
			return (EFBIG);
		/*
		 * If the next write will extend the data into a new block,
		 * and the data is currently composed of a fragment
		 * this fragment has to be extended to be a full block.
		 */
		lastlbn = lblkno(fs, dp->di_extsize);
		if (lastlbn < lbn) {
			nb = lastlbn;
			osize = sblksize(fs, dp->di_extsize, nb);
			if (osize < fs->fs_bsize && osize > 0) {
				UFS_LOCK(ump);
				error = ffs_realloccg(ip, -1 - nb,
				    dp->di_extb[nb],
				    ffs_blkpref_ufs2(ip, lastlbn, (int)nb,
				    &dp->di_extb[0]), osize,
				    (int)fs->fs_bsize, flags, cred, &bp);
				if (error)
					return (error);
				if (DOINGSOFTDEP(vp))
					softdep_setup_allocext(ip, nb,
					    dbtofsb(fs, bp->b_blkno),
					    dp->di_extb[nb],
					    fs->fs_bsize, osize, bp);
				dp->di_extsize = smalllblktosize(fs, nb + 1);
				dp->di_extb[nb] = dbtofsb(fs, bp->b_blkno);
				bp->b_xflags |= BX_ALTDATA;
				ip->i_flag |= IN_CHANGE;
				if (flags & IO_SYNC)
					bwrite(bp);
				else
					bawrite(bp);
			}
		}
		/*
		 * All blocks are direct blocks
		 */
		if (flags & BA_METAONLY)
			panic("ffs_balloc_ufs2: BA_METAONLY for ext block");
		nb = dp->di_extb[lbn];
		if (nb != 0 && dp->di_extsize >= smalllblktosize(fs, lbn + 1)) {
			error = bread_gb(vp, -1 - lbn, fs->fs_bsize, NOCRED,
			    gbflags, &bp);
			if (error) {
				brelse(bp);
				return (error);
			}
			bp->b_blkno = fsbtodb(fs, nb);
			bp->b_xflags |= BX_ALTDATA;
			*bpp = bp;
			return (0);
		}
		if (nb != 0) {
			/*
			 * Consider need to reallocate a fragment.
			 */
			osize = fragroundup(fs, blkoff(fs, dp->di_extsize));
			nsize = fragroundup(fs, size);
			if (nsize <= osize) {
				error = bread_gb(vp, -1 - lbn, osize, NOCRED,
				    gbflags, &bp);
				if (error) {
					brelse(bp);
					return (error);
				}
				bp->b_blkno = fsbtodb(fs, nb);
				bp->b_xflags |= BX_ALTDATA;
			} else {
				UFS_LOCK(ump);
				error = ffs_realloccg(ip, -1 - lbn,
				    dp->di_extb[lbn],
				    ffs_blkpref_ufs2(ip, lbn, (int)lbn,
				    &dp->di_extb[0]), osize, nsize, flags,
				    cred, &bp);
				if (error)
					return (error);
				bp->b_xflags |= BX_ALTDATA;
				if (DOINGSOFTDEP(vp))
					softdep_setup_allocext(ip, lbn,
					    dbtofsb(fs, bp->b_blkno), nb,
					    nsize, osize, bp);
			}
		} else {
			if (dp->di_extsize < smalllblktosize(fs, lbn + 1))
				nsize = fragroundup(fs, size);
			else
				nsize = fs->fs_bsize;
			UFS_LOCK(ump);
			error = ffs_alloc(ip, lbn,
			   ffs_blkpref_ufs2(ip, lbn, (int)lbn, &dp->di_extb[0]),
			   nsize, flags, cred, &newb);
			if (error)
				return (error);
			bp = getblk(vp, -1 - lbn, nsize, 0, 0, gbflags);
			bp->b_blkno = fsbtodb(fs, newb);
			bp->b_xflags |= BX_ALTDATA;
			if (flags & BA_CLRBUF)
				vfs_bio_clrbuf(bp);
			if (DOINGSOFTDEP(vp))
				softdep_setup_allocext(ip, lbn, newb, 0,
				    nsize, 0, bp);
		}
		dp->di_extb[lbn] = dbtofsb(fs, bp->b_blkno);
		ip->i_flag |= IN_CHANGE;
		*bpp = bp;
		return (0);
	}
	/*
	 * If the next write will extend the file into a new block,
	 * and the file is currently composed of a fragment
	 * this fragment has to be extended to be a full block.
	 */
	lastlbn = lblkno(fs, ip->i_size);
	if (lastlbn < UFS_NDADDR && lastlbn < lbn) {
		nb = lastlbn;
		osize = blksize(fs, ip, nb);
		if (osize < fs->fs_bsize && osize > 0) {
			UFS_LOCK(ump);
			error = ffs_realloccg(ip, nb, dp->di_db[nb],
			    ffs_blkpref_ufs2(ip, lastlbn, (int)nb,
			    &dp->di_db[0]), osize, (int)fs->fs_bsize,
			    flags, cred, &bp);
			if (error)
				return (error);
			if (DOINGSOFTDEP(vp))
				softdep_setup_allocdirect(ip, nb,
				    dbtofsb(fs, bp->b_blkno),
				    dp->di_db[nb],
				    fs->fs_bsize, osize, bp);
			ip->i_size = smalllblktosize(fs, nb + 1);
			dp->di_size = ip->i_size;
			dp->di_db[nb] = dbtofsb(fs, bp->b_blkno);
			ip->i_flag |= IN_CHANGE | IN_UPDATE;
			if (flags & IO_SYNC)
				bwrite(bp);
			else
				bawrite(bp);
		}
	}
	/*
	 * The first UFS_NDADDR blocks are direct blocks
	 */
	if (lbn < UFS_NDADDR) {
		if (flags & BA_METAONLY)
			panic("ffs_balloc_ufs2: BA_METAONLY for direct block");
		nb = dp->di_db[lbn];
		if (nb != 0 && ip->i_size >= smalllblktosize(fs, lbn + 1)) {
			error = bread_gb(vp, lbn, fs->fs_bsize, NOCRED,
			    gbflags, &bp);
			if (error) {
				brelse(bp);
				return (error);
			}
			bp->b_blkno = fsbtodb(fs, nb);
			*bpp = bp;
			return (0);
		}
		if (nb != 0) {
			/*
			 * Consider need to reallocate a fragment.
			 */
			osize = fragroundup(fs, blkoff(fs, ip->i_size));
			nsize = fragroundup(fs, size);
			if (nsize <= osize) {
				error = bread_gb(vp, lbn, osize, NOCRED,
				    gbflags, &bp);
				if (error) {
					brelse(bp);
					return (error);
				}
				bp->b_blkno = fsbtodb(fs, nb);
			} else {
				UFS_LOCK(ump);
				error = ffs_realloccg(ip, lbn, dp->di_db[lbn],
				    ffs_blkpref_ufs2(ip, lbn, (int)lbn,
				    &dp->di_db[0]), osize, nsize, flags,
				    cred, &bp);
				if (error)
					return (error);
				if (DOINGSOFTDEP(vp))
					softdep_setup_allocdirect(ip, lbn,
					    dbtofsb(fs, bp->b_blkno), nb,
					    nsize, osize, bp);
			}
		} else {
			if (ip->i_size < smalllblktosize(fs, lbn + 1))
				nsize = fragroundup(fs, size);
			else
				nsize = fs->fs_bsize;
			UFS_LOCK(ump);
			error = ffs_alloc(ip, lbn,
			    ffs_blkpref_ufs2(ip, lbn, (int)lbn,
				&dp->di_db[0]), nsize, flags, cred, &newb);
			if (error)
				return (error);
			bp = getblk(vp, lbn, nsize, 0, 0, gbflags);
			bp->b_blkno = fsbtodb(fs, newb);
			if (flags & BA_CLRBUF)
				vfs_bio_clrbuf(bp);
			if (DOINGSOFTDEP(vp))
				softdep_setup_allocdirect(ip, lbn, newb, 0,
				    nsize, 0, bp);
		}
		dp->di_db[lbn] = dbtofsb(fs, bp->b_blkno);
		ip->i_flag |= IN_CHANGE | IN_UPDATE;
		*bpp = bp;
		return (0);
	}
	/*
	 * Determine the number of levels of indirection.
	 */
	pref = 0;
	if ((error = ufs_getlbns(vp, lbn, indirs, &num)) != 0)
		return(error);
#ifdef INVARIANTS
	if (num < 1)
		panic ("ffs_balloc_ufs2: ufs_getlbns returned indirect block");
#endif
	saved_inbdflush = curthread_pflags_set(TDP_INBDFLUSH);
	/*
	 * Fetch the first indirect block allocating if necessary.
	 */
	--num;
	nb = dp->di_ib[indirs[0].in_off];
	allocib = nil;
	allocblk = allociblk;
	lbns_remfree = lbns;
	if (nb == 0) {
		UFS_LOCK(ump);
		pref = ffs_blkpref_ufs2(ip, lbn, -indirs[0].in_off - 1,
		    (ufs2_daddr_t *)0);
		if ((error = ffs_alloc(ip, lbn, pref, (int)fs->fs_bsize,
		    flags, cred, &newb)) != 0) {
			curthread_pflags_restore(saved_inbdflush);
			return (error);
		}
		pref = newb + fs->fs_frag;
		nb = newb;
		MPASS(allocblk < allociblk + nitems(allociblk));
		MPASS(lbns_remfree < lbns + nitems(lbns));
		*allocblk++ = nb;
		*lbns_remfree++ = indirs[1].in_lbn;
		bp = getblk(vp, indirs[1].in_lbn, fs->fs_bsize, 0, 0,
		    GB_UNMAPPED);
		bp->b_blkno = fsbtodb(fs, nb);
		vfs_bio_clrbuf(bp);
		if (DOINGSOFTDEP(vp)) {
			softdep_setup_allocdirect(ip,
			    UFS_NDADDR + indirs[0].in_off, newb, 0,
			    fs->fs_bsize, 0, bp);
			bdwrite(bp);
		} else if ((flags & IO_SYNC) == 0 && DOINGASYNC(vp)) {
			if (bp->b_bufsize == fs->fs_bsize)
				bp->b_flags |= B_CLUSTEROK;
			bdwrite(bp);
		} else {
			if ((error = bwrite(bp)) != 0)
				goto fail;
		}
		allocib = &dp->di_ib[indirs[0].in_off];
		*allocib = nb;
		ip->i_flag |= IN_CHANGE | IN_UPDATE;
	}
	/*
	 * Fetch through the indirect blocks, allocating as necessary.
	 */
retry:
	for (i = 1;;) {
		error = bread(vp,
		    indirs[i].in_lbn, (int)fs->fs_bsize, NOCRED, &bp);
		if (error) {
			brelse(bp);
			goto fail;
		}
		bap = (ufs2_daddr_t *)bp->b_data;
		nb = bap[indirs[i].in_off];
		if (i == num)
			break;
		i += 1;
		if (nb != 0) {
			bqrelse(bp);
			continue;
		}
		UFS_LOCK(ump);
		/*
		 * If parent indirect has just been allocated, try to cluster
		 * immediately following it.
		 */
		if (pref == 0)
			pref = ffs_blkpref_ufs2(ip, lbn, i - num - 1,
			    (ufs2_daddr_t *)0);
		if ((error = ffs_alloc(ip, lbn, pref, (int)fs->fs_bsize,
		    flags | IO_BUFLOCKED, cred, &newb)) != 0) {
			brelse(bp);
			if (DOINGSOFTDEP(vp) && ++reclaimed == 1) {
				UFS_LOCK(ump);
				softdep_request_cleanup(fs, vp, cred,
				    FLUSH_BLOCKS_WAIT);
				UFS_UNLOCK(ump);
				goto retry;
			}
			if (ppsratecheck(&lastfail, &curfail, 1)) {
				ffs_fserr(fs, ip->i_number, "filesystem full");
				uprintf("\n%s: write failed, filesystem "
				    "is full\n", fs->fs_fsmnt);
			}
			goto fail;
		}
		pref = newb + fs->fs_frag;
		nb = newb;
		MPASS(allocblk < allociblk + nitems(allociblk));
		MPASS(lbns_remfree < lbns + nitems(lbns));
		*allocblk++ = nb;
		*lbns_remfree++ = indirs[i].in_lbn;
		nbp = getblk(vp, indirs[i].in_lbn, fs->fs_bsize, 0, 0,
		    GB_UNMAPPED);
		nbp->b_blkno = fsbtodb(fs, nb);
		vfs_bio_clrbuf(nbp);
		if (DOINGSOFTDEP(vp)) {
			softdep_setup_allocindir_meta(nbp, ip, bp,
			    indirs[i - 1].in_off, nb);
			bdwrite(nbp);
		} else if ((flags & IO_SYNC) == 0 && DOINGASYNC(vp)) {
			if (nbp->b_bufsize == fs->fs_bsize)
				nbp->b_flags |= B_CLUSTEROK;
			bdwrite(nbp);
		} else {
			if ((error = bwrite(nbp)) != 0) {
				brelse(bp);
				goto fail;
			}
		}
		bap[indirs[i - 1].in_off] = nb;
		if (allocib == nil && unwindidx < 0)
			unwindidx = i - 1;
		/*
		 * If required, write synchronously, otherwise use
		 * delayed write.
		 */
		if (flags & IO_SYNC) {
			bwrite(bp);
		} else {
			if (bp->b_bufsize == fs->fs_bsize)
				bp->b_flags |= B_CLUSTEROK;
			bdwrite(bp);
		}
	}
	/*
	 * If asked only for the indirect block, then return it.
	 */
	if (flags & BA_METAONLY) {
		curthread_pflags_restore(saved_inbdflush);
		*bpp = bp;
		return (0);
	}
	/*
	 * Get the data block, allocating if necessary.
	 */
	if (nb == 0) {
		UFS_LOCK(ump);
		/*
		 * If allocating metadata at the front of the cylinder
		 * group and parent indirect block has just been allocated,
		 * then cluster next to it if it is the first indirect in
		 * the file. Otherwise it has been allocated in the metadata
		 * area, so we want to find our own place out in the data area.
		 */
		if (pref == 0 || (lbn > UFS_NDADDR && fs->fs_metaspace != 0))
			pref = ffs_blkpref_ufs2(ip, lbn, indirs[i].in_off,
			    &bap[0]);
		error = ffs_alloc(ip, lbn, pref, (int)fs->fs_bsize,
		    flags | IO_BUFLOCKED, cred, &newb);
		if (error) {
			brelse(bp);
			if (DOINGSOFTDEP(vp) && ++reclaimed == 1) {
				UFS_LOCK(ump);
				softdep_request_cleanup(fs, vp, cred,
				    FLUSH_BLOCKS_WAIT);
				UFS_UNLOCK(ump);
				goto retry;
			}
			if (ppsratecheck(&lastfail, &curfail, 1)) {
				ffs_fserr(fs, ip->i_number, "filesystem full");
				uprintf("\n%s: write failed, filesystem "
				    "is full\n", fs->fs_fsmnt);
			}
			goto fail;
		}
		nb = newb;
		MPASS(allocblk < allociblk + nitems(allociblk));
		MPASS(lbns_remfree < lbns + nitems(lbns));
		*allocblk++ = nb;
		*lbns_remfree++ = lbn;
		nbp = getblk(vp, lbn, fs->fs_bsize, 0, 0, gbflags);
		nbp->b_blkno = fsbtodb(fs, nb);
		if (flags & BA_CLRBUF)
			vfs_bio_clrbuf(nbp);
		if (DOINGSOFTDEP(vp))
			softdep_setup_allocindir_page(ip, lbn, bp,
			    indirs[i].in_off, nb, 0, nbp);
		bap[indirs[i].in_off] = nb;
		/*
		 * If required, write synchronously, otherwise use
		 * delayed write.
		 */
		if (flags & IO_SYNC) {
			bwrite(bp);
		} else {
			if (bp->b_bufsize == fs->fs_bsize)
				bp->b_flags |= B_CLUSTEROK;
			bdwrite(bp);
		}
		curthread_pflags_restore(saved_inbdflush);
		*bpp = nbp;
		return (0);
	}
	brelse(bp);
	/*
	 * If requested clear invalid portions of the buffer.  If we
	 * have to do a read-before-write (typical if BA_CLRBUF is set),
	 * try to do some read-ahead in the sequential case to reduce
	 * the number of I/O transactions.
	 */
	if (flags & BA_CLRBUF) {
		int seqcount = (flags & BA_SEQMASK) >> BA_SEQSHIFT;
		if (seqcount != 0 &&
		    (vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0 &&
		    !(vm_page_count_severe() || buf_dirty_count_severe())) {
			error = cluster_read(vp, ip->i_size, lbn,
			    (int)fs->fs_bsize, NOCRED,
			    MAXBSIZE, seqcount, gbflags, &nbp);
		} else {
			error = bread_gb(vp, lbn, (int)fs->fs_bsize,
			    NOCRED, gbflags, &nbp);
		}
		if (error) {
			brelse(nbp);
			goto fail;
		}
	} else {
コード例 #15
0
ファイル: ext4_readwrite.c プロジェクト: truncs/ext4fs
/*
 * this function handles traditional block mapping
 */
static int
ext2_ind_read(struct vop_read_args *ap)
{
	struct vnode *vp;
	struct inode *ip;
	struct uio *uio;
	FS *fs;
	struct buf *bp;
	daddr_t lbn, nextlbn;
	off_t bytesinfile;
	long size, xfersize, blkoffset;
	int error, orig_resid, seqcount;
	seqcount = ap->a_ioflag >> IO_SEQSHIFT;
	u_short mode;

	vp = ap->a_vp;
	ip = VTOI(vp);
	mode = ip->i_mode;
	uio = ap->a_uio;

#ifdef DIAGNOSTIC
	if (uio->uio_rw != UIO_READ)
		panic("%s: mode", READ_S);

	if (vp->v_type == VLNK) {
		if ((int)ip->i_size < vp->v_mount->mnt_maxsymlinklen)
			panic("%s: short symlink", READ_S);
	} else if (vp->v_type != VREG && vp->v_type != VDIR)
		panic("%s: type %d", READ_S, vp->v_type);
#endif
	orig_resid = uio->uio_resid;
	KASSERT(orig_resid >= 0, ("ext2_read: uio->uio_resid < 0"));
	if (orig_resid == 0)
		return (0);
	KASSERT(uio->uio_offset >= 0, ("ext2_read: uio->uio_offset < 0"));
	fs = ip->I_FS;
	if (uio->uio_offset < ip->i_size && uio->uio_offset >= fs->e2fs_maxfilesize)
		return (EOVERFLOW);
	for (error = 0, bp = NULL; uio->uio_resid > 0; bp = NULL) {
		if ((bytesinfile = ip->i_size - uio->uio_offset) <= 0)
			break;
		lbn = lblkno(fs, uio->uio_offset);
		nextlbn = lbn + 1;
		size = BLKSIZE(fs, ip, lbn);
		blkoffset = blkoff(fs, uio->uio_offset);

		xfersize = fs->e2fs_fsize - blkoffset;
		if (uio->uio_resid < xfersize)
			xfersize = uio->uio_resid;
		if (bytesinfile < xfersize)
			xfersize = bytesinfile;

		if (lblktosize(fs, nextlbn) >= ip->i_size)
			error = bread(vp, lbn, size, NOCRED, &bp);
		else if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0)
		error = cluster_read(vp, ip->i_size, lbn, size,
  			NOCRED, blkoffset + uio->uio_resid, seqcount, &bp);
		else if (seqcount > 1) {
			int nextsize = BLKSIZE(fs, ip, nextlbn);
			error = breadn(vp, lbn,
			    size, &nextlbn, &nextsize, 1, NOCRED, &bp);
		} else
			error = bread(vp, lbn, size, NOCRED, &bp);
		if (error) {
			brelse(bp);
			bp = NULL;
			break;
		}

		/*
		 * We should only get non-zero b_resid when an I/O error
		 * has occurred, which should cause us to break above.
		 * However, if the short read did not cause an error,
		 * then we want to ensure that we do not uiomove bad
		 * or uninitialized data.
		 */
		size -= bp->b_resid;
		if (size < xfersize) {
			if (size == 0)
				break;
			xfersize = size;
		}
		error = uiomove((char *)bp->b_data + blkoffset,
  			(int)xfersize, uio);
		if (error)
			break;

		bqrelse(bp);
	}
	if (bp != NULL)
		bqrelse(bp);
	if ((error == 0 || uio->uio_resid != orig_resid) &&
	    (vp->v_mount->mnt_flag & MNT_NOATIME) == 0)
		ip->i_flag |= IN_ACCESS;
	return (error);
}