Add a vfs helper for implementing lseek SEEK_HOLE / SEEK_DATA support
via iomap. Wire up in gfs2.
Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
---
fs/gfs2/file.c | 14 ++++++++++---
fs/gfs2/inode.c | 32 ++++++++++++++++++++++++++++++
fs/gfs2/inode.h | 1 +
fs/iomap.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/iomap.h | 2 ++
5 files changed, 101 insertions(+), 3 deletions(-)
diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index c2062a1..62ce320 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -60,9 +60,7 @@ static loff_t gfs2_llseek(struct file *file, loff_t offset, int whence)
loff_t error;
switch (whence) {
- case SEEK_END: /* These reference inode->i_size */
- case SEEK_DATA:
- case SEEK_HOLE:
+ case SEEK_END:
error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY,
&i_gh);
if (!error) {
@@ -70,8 +68,18 @@ static loff_t gfs2_llseek(struct file *file, loff_t offset, int whence)
gfs2_glock_dq_uninit(&i_gh);
}
break;
+
+ case SEEK_DATA:
+ case SEEK_HOLE:
+ error = gfs2_seek_hole_data(file, offset, whence);
+ break;
+
case SEEK_CUR:
case SEEK_SET:
+ /*
+ * These don't reference inode->i_size and don't depend on the
+ * block mapping, so we don't need the glock.
+ */
error = generic_file_llseek(file, offset, whence);
break;
default:
diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index 9ed2e91..f3bf740 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -2046,6 +2046,38 @@ static int gfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
return ret;
}
+loff_t gfs2_seek_hole_data(struct file *file, loff_t offset, int whence)
+{
+ struct inode *inode = file->f_mapping->host;
+ struct gfs2_inode *ip = GFS2_I(inode);
+ struct gfs2_holder gh;
+ loff_t ret;
+
+ inode_lock(inode);
+ ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
+ if (ret)
+ goto out;
+ if (gfs2_is_stuffed(ip)) {
+ u64 size = i_size_read(inode);
+
+ if (offset >= size) {
+ ret = -ENXIO;
+ goto out_dequeue;
+ }
+ ret = offset;
+ if (whence == SEEK_HOLE)
+ ret = size;
+ } else {
+ ret = iomap_seek_hole_data(inode, offset, whence, &gfs2_iomap_ops);
+ }
+
+out_dequeue:
+ gfs2_glock_dq_uninit(&gh);
+out:
+ inode_unlock(inode);
+ return ret;
+}
+
const struct inode_operations gfs2_file_iops = {
.permission = gfs2_permission,
.setattr = gfs2_setattr,
diff --git a/fs/gfs2/inode.h b/fs/gfs2/inode.h
index aace8ce..9e64b05 100644
--- a/fs/gfs2/inode.h
+++ b/fs/gfs2/inode.h
@@ -109,6 +109,7 @@ extern int gfs2_setattr_simple(struct inode *inode, struct iattr *attr);
extern struct inode *gfs2_lookup_simple(struct inode *dip, const char *name);
extern void gfs2_dinode_out(const struct gfs2_inode *ip, void *buf);
extern int gfs2_open_common(struct inode *inode, struct file *file);
+extern loff_t gfs2_seek_hole_data(struct file *file, loff_t pos, int whence);
extern const struct inode_operations gfs2_file_iops;
extern const struct inode_operations gfs2_dir_iops;
diff --git a/fs/iomap.c b/fs/iomap.c
index 4b10892..59350ef 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -584,6 +584,61 @@ int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi,
}
EXPORT_SYMBOL_GPL(iomap_fiemap);
+static loff_t
+iomap_seek_hole_actor(struct inode *inode, loff_t offset, loff_t length,
+ void *data, struct iomap *iomap)
+{
+ if (iomap->type == IOMAP_HOLE)
+ return 0;
+ return iomap->offset + iomap->length - offset;
+}
+
+static loff_t
+iomap_seek_data_actor(struct inode *inode, loff_t offset, loff_t length,
+ void *data, struct iomap *iomap)
+{
+ if (iomap->type != IOMAP_HOLE)
+ return 0;
+ return iomap->offset + iomap->length - offset;
+}
+
+loff_t
+iomap_seek_hole_data(struct inode *inode, loff_t offset, int whence,
+ const struct iomap_ops *ops)
+{
+ static loff_t (*actor)(struct inode *, loff_t, loff_t, void *, struct iomap *);
+ loff_t len = i_size_read(inode) - offset;
+ loff_t ret;
+
+ if (len <= 0)
+ return -ENXIO;
+
+ switch(whence) {
+ case SEEK_HOLE:
+ actor = iomap_seek_hole_actor;
+ break;
+
+ case SEEK_DATA:
+ actor = iomap_seek_data_actor;
+ break;
+ }
+
+ while (len > 0) {
+ ret = iomap_apply(inode, offset, len, IOMAP_REPORT, ops, NULL, actor);
+ if (ret <= 0)
+ break;
+ offset += ret;
+ len -= ret;
+ }
+ if (ret < 0)
+ return ret;
+ ret = offset;
+ if (len <= 0 && whence == SEEK_DATA)
+ ret = -ENXIO;
+ return ret;
+}
+EXPORT_SYMBOL_GPL(iomap_seek_hole_data);
+
/*
* Private flags for iomap_dio, must not overlap with the public ones in
* iomap.h:
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 9d64933..63bd998 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -84,6 +84,8 @@ int iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
int iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops);
int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
loff_t start, loff_t len, const struct iomap_ops *ops);
+loff_t iomap_seek_hole_data(struct inode *inode, loff_t pos, int whence,
+ const struct iomap_ops *ops);
/*
* Flags for direct I/O ->end_io:
--
2.7.4
