ocfs2 implements its own llseek() to provide the SEEK_HOLE/SEEK_DATA
functionality.
As SEEK_DATA is used to detect regions having non-zero data, the patch
opts to treat unwritten extents as holes.
Signed-off-by: Sunil Mushran <sunil.mushran at oracle.com>
---
fs/ocfs2/extent_map.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++
fs/ocfs2/extent_map.h | 2 +
fs/ocfs2/file.c | 58 ++++++++++++++++++++++++++++++++++-
3 files changed, 137 insertions(+), 2 deletions(-)
diff --git a/fs/ocfs2/extent_map.c b/fs/ocfs2/extent_map.c
index 23457b4..4f6cf92 100644
--- a/fs/ocfs2/extent_map.c
+++ b/fs/ocfs2/extent_map.c
@@ -832,6 +832,85 @@ out:
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, is_last;
+ u32 cpos, cend, cs_bits = OCFS2_SB(inode->i_sb)->s_clustersize_bits;
+ loff_t bpos;
+ unsigned int hole_size;
+ 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 (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL)
+ goto out_unlock;
+
+ cpos = *offset >> cs_bits;
+ cend = ocfs2_clusters_for_bytes(inode->i_sb, inode->i_size);
+ is_last = 0;
+
+ 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;
+ }
+
+ /* unwritten extent is treated as a hole */
+ if (rec.e_blkno == 0ULL || rec.e_flags & OCFS2_EXT_UNWRITTEN) {
+ if (origin == SEEK_HOLE) {
+ bpos = cpos << cs_bits;
+ if (bpos > *offset)
+ *offset = bpos;
+ goto out_unlock;
+ }
+ if (rec.e_blkno == 0ULL) {
+ cpos += hole_size;
+ continue;
+ }
+ cpos = le32_to_cpu(rec.e_cpos) +
+ le16_to_cpu(rec.e_leaf_clusters);
+ continue;
+ }
+
+ if (origin == SEEK_DATA) {
+ bpos = cpos << cs_bits;
+ if (bpos > *offset)
+ *offset = bpos;
+ goto out_unlock;
+ }
+
+ cpos = le32_to_cpu(rec.e_cpos) +
+ le16_to_cpu(rec.e_leaf_clusters);
+ }
+
+ if (origin == SEEK_HOLE && *offset < inode->i_size)
+ *offset = inode->i_size;
+
+ if (ret > 0)
+ ret = 0;
+
+out_unlock:
+ brelse(di_bh);
+
+ up_read(&OCFS2_I(inode)->ip_alloc_sem);
+
+ ocfs2_inode_unlock(inode, 0);
+out:
+ 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,
diff --git a/fs/ocfs2/extent_map.h b/fs/ocfs2/extent_map.h
index e79d41c..67ea57d 100644
--- a/fs/ocfs2/extent_map.h
+++ b/fs/ocfs2/extent_map.h
@@ -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,
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 41565ae..48340f3 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2572,6 +2572,60 @@ bail:
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_END:
+ offset += inode->i_size;
+ break;
+ case SEEK_CUR:
+ /*
+ * Here we special-case the lseek(fd, 0, SEEK_CUR)
+ * position-querying operation. Avoid rewriting the "same"
+ * f_pos value back to the file because a concurrent read(),
+ * write() or lseek() might have altered it
+ */
+ 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;
+ }
+
+ ret = -EINVAL;
+ if (offset < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET))
+ goto out;
+ if (offset > inode->i_sb->s_maxbytes)
+ goto out;
+ if (origin == SEEK_DATA && offset >= inode->i_size)
+ goto out;
+ if (origin == SEEK_HOLE && offset > inode->i_size)
+ goto out;
+
+ /* Special lock needed here? */
+ if (offset != file->f_pos) {
+ file->f_pos = offset;
+ file->f_version = 0;
+ }
+ ret = 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,
@@ -2594,7 +2648,7 @@ 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,
@@ -2642,7 +2696,7 @@ 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,
--
1.7.1