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Commit 93862d5e authored by Sunil Mushran's avatar Sunil Mushran
Browse files

ocfs2: Implement llseek() 



ocfs2 implements its own llseek() to provide the SEEK_HOLE/SEEK_DATA
functionality.

SEEK_HOLE sets the file pointer to the start of either a hole or an unwritten
(preallocated) extent, that is greater than or equal to the supplied offset.

SEEK_DATA sets the file pointer to the start of an allocated extent (not
unwritten) that is greater than or equal to the supplied offset.

If the supplied offset is on a desired region, then the file pointer is set
to it. Offsets greater than or equal to the file size return -ENXIO.

Unwritten (preallocated) extents are considered holes because the file system
treats reads to such regions in the same way as it does to holes.

Signed-off-by: default avatarSunil Mushran <sunil.mushran@oracle.com>
parent 5cffff9e

fs/ocfs2/extent_map.c

+96 −0
Original line number Diff line number Diff line
@@ -832,6 +832,102 @@ int ocfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, 
	return ret;

}



int ocfs2_seek_data_hole_offset(struct file *file, loff_t *offset, int origin)

{

	struct inode *inode = file->f_mapping->host;

	int ret;

	unsigned int is_last = 0, is_data = 0;

	u16 cs_bits = OCFS2_SB(inode->i_sb)->s_clustersize_bits;

	u32 cpos, cend, clen, hole_size;

	u64 extoff, extlen;

	struct buffer_head *di_bh = NULL;

	struct ocfs2_extent_rec rec;



	BUG_ON(origin != SEEK_DATA && origin != SEEK_HOLE);



	ret = ocfs2_inode_lock(inode, &di_bh, 0);

	if (ret) {

		mlog_errno(ret);

		goto out;

	}



	down_read(&OCFS2_I(inode)->ip_alloc_sem);



	if (*offset >= inode->i_size) {

		ret = -ENXIO;

		goto out_unlock;

	}



	if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {

		if (origin == SEEK_HOLE)

			*offset = inode->i_size;

		goto out_unlock;

	}



	clen = 0;

	cpos = *offset >> cs_bits;

	cend = ocfs2_clusters_for_bytes(inode->i_sb, inode->i_size);



	while (cpos < cend && !is_last) {

		ret = ocfs2_get_clusters_nocache(inode, di_bh, cpos, &hole_size,

						 &rec, &is_last);

		if (ret) {

			mlog_errno(ret);

			goto out_unlock;

		}



		extoff = cpos;

		extoff <<= cs_bits;



		if (rec.e_blkno == 0ULL) {

			clen = hole_size;

			is_data = 0;

		} else {

			clen = le16_to_cpu(rec.e_leaf_clusters) -

				(cpos - le32_to_cpu(rec.e_cpos));

			is_data = (rec.e_flags & OCFS2_EXT_UNWRITTEN) ?  0 : 1;

		}



		if ((!is_data && origin == SEEK_HOLE) ||

		    (is_data && origin == SEEK_DATA)) {

			if (extoff > *offset)

				*offset = extoff;

			goto out_unlock;

		}



		if (!is_last)

			cpos += clen;

	}



	if (origin == SEEK_HOLE) {

		extoff = cpos;

		extoff <<= cs_bits;

		extlen = clen;

		extlen <<=  cs_bits;



		if ((extoff + extlen) > inode->i_size)

			extlen = inode->i_size - extoff;

		extoff += extlen;

		if (extoff > *offset)

			*offset = extoff;

		goto out_unlock;

	}



	ret = -ENXIO;



out_unlock:



	brelse(di_bh);



	up_read(&OCFS2_I(inode)->ip_alloc_sem);



	ocfs2_inode_unlock(inode, 0);

out:

	if (ret && ret != -ENXIO)

		ret = -ENXIO;

	return ret;

}



int ocfs2_read_virt_blocks(struct inode *inode, u64 v_block, int nr,

			   struct buffer_head *bhs[], int flags,

			   int (*validate)(struct super_block *sb,

fs/ocfs2/extent_map.h

+2 −0
Original line number Diff line number Diff line
@@ -53,6 +53,8 @@ int ocfs2_extent_map_get_blocks(struct inode *inode, u64 v_blkno, u64 *p_blkno, 
int ocfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,

		 u64 map_start, u64 map_len);



int ocfs2_seek_data_hole_offset(struct file *file, loff_t *offset, int origin);



int ocfs2_xattr_get_clusters(struct inode *inode, u32 v_cluster,

			     u32 *p_cluster, u32 *num_clusters,

			     struct ocfs2_extent_list *el,

fs/ocfs2/file.c

+53 −2
Original line number Diff line number Diff line
@@ -2591,6 +2591,57 @@ static ssize_t ocfs2_file_aio_read(struct kiocb *iocb, 
	return ret;

}



/* Refer generic_file_llseek_unlocked() */

static loff_t ocfs2_file_llseek(struct file *file, loff_t offset, int origin)

{

	struct inode *inode = file->f_mapping->host;

	int ret = 0;



	mutex_lock(&inode->i_mutex);



	switch (origin) {

	case SEEK_SET:

		break;

	case SEEK_END:

		offset += inode->i_size;

		break;

	case SEEK_CUR:

		if (offset == 0) {

			offset = file->f_pos;

			goto out;

		}

		offset += file->f_pos;

		break;

	case SEEK_DATA:

	case SEEK_HOLE:

		ret = ocfs2_seek_data_hole_offset(file, &offset, origin);

		if (ret)

			goto out;

		break;

	default:

		ret = -EINVAL;

		goto out;

	}



	if (offset < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET))

		ret = -EINVAL;

	if (!ret && offset > inode->i_sb->s_maxbytes)

		ret = -EINVAL;

	if (ret)

		goto out;



	if (offset != file->f_pos) {

		file->f_pos = offset;

		file->f_version = 0;

	}



out:

	mutex_unlock(&inode->i_mutex);

	if (ret)

		return ret;

	return offset;

}



const struct inode_operations ocfs2_file_iops = {

	.setattr	= ocfs2_setattr,

	.getattr	= ocfs2_getattr,
@@ -2615,7 +2666,7 @@ const struct inode_operations ocfs2_special_file_iops = { 
 * ocfs2_fops_no_plocks and ocfs2_dops_no_plocks!

 */

const struct file_operations ocfs2_fops = {

	.llseek		= generic_file_llseek,

	.llseek		= ocfs2_file_llseek,

	.read		= do_sync_read,

	.write		= do_sync_write,

	.mmap		= ocfs2_mmap,
@@ -2663,7 +2714,7 @@ const struct file_operations ocfs2_dops = { 
 * the cluster.

 */

const struct file_operations ocfs2_fops_no_plocks = {

	.llseek		= generic_file_llseek,

	.llseek		= ocfs2_file_llseek,

	.read		= do_sync_read,

	.write		= do_sync_write,

	.mmap		= ocfs2_mmap,