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

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
......@@ -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,
......
......@@ -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,
......
......@@ -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,
......
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