Sunil Mushran
2011-May-23 23:55 UTC
[Ocfs2-devel] PATCH v3: Add support SEEK_DATA/HOLE in ocfs2
The following patch implements SEEK_DATA/HOLE on ocfs2. The patch has been tested atop Josef's v4 patch series. Logs of successful runs on btrfs, ext3, ext4 and ocfs2 are available here: http://oss.oracle.com/~smushran/seek_data/ Thanks Sunil
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: Sunil Mushran <sunil.mushran at oracle.com>
---
fs/ocfs2/extent_map.c | 96 +++++++++++++++++++++++++++++++++++++++++++++++++
fs/ocfs2/extent_map.h | 2 +
fs/ocfs2/file.c | 53 ++++++++++++++++++++++++++-
3 files changed, 149 insertions(+), 2 deletions(-)
diff --git a/fs/ocfs2/extent_map.c b/fs/ocfs2/extent_map.c
index 23457b4..2f5b92e 100644
--- a/fs/ocfs2/extent_map.c
+++ b/fs/ocfs2/extent_map.c
@@ -832,6 +832,102 @@ 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;
+ 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,
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 b1e35a3..13f7d03 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2584,6 +2584,55 @@ 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:
+ 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,
@@ -2606,7 +2655,7 @@ 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,
@@ -2654,7 +2703,7 @@ 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,
--
1.7.4.1