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path: root/fs/overlayfs/copy_up.c
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Diffstat (limited to 'fs/overlayfs/copy_up.c')
-rw-r--r--fs/overlayfs/copy_up.c43
1 files changed, 40 insertions, 3 deletions
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 6220642fe113..9fc47c2e078d 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -24,7 +24,7 @@
static int ovl_ccup_set(const char *buf, const struct kernel_param *param)
{
- pr_warn("overlayfs: \"check_copy_up\" module option is obsolete\n");
+ pr_warn("\"check_copy_up\" module option is obsolete\n");
return 0;
}
@@ -123,6 +123,9 @@ static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
loff_t old_pos = 0;
loff_t new_pos = 0;
loff_t cloned;
+ loff_t data_pos = -1;
+ loff_t hole_len;
+ bool skip_hole = false;
int error = 0;
if (len == 0)
@@ -144,7 +147,11 @@ static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
goto out;
/* Couldn't clone, so now we try to copy the data */
- /* FIXME: copy up sparse files efficiently */
+ /* Check if lower fs supports seek operation */
+ if (old_file->f_mode & FMODE_LSEEK &&
+ old_file->f_op->llseek)
+ skip_hole = true;
+
while (len) {
size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
long bytes;
@@ -157,6 +164,36 @@ static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
break;
}
+ /*
+ * Fill zero for hole will cost unnecessary disk space
+ * and meanwhile slow down the copy-up speed, so we do
+ * an optimization for hole during copy-up, it relies
+ * on SEEK_DATA implementation in lower fs so if lower
+ * fs does not support it, copy-up will behave as before.
+ *
+ * Detail logic of hole detection as below:
+ * When we detect next data position is larger than current
+ * position we will skip that hole, otherwise we copy
+ * data in the size of OVL_COPY_UP_CHUNK_SIZE. Actually,
+ * it may not recognize all kind of holes and sometimes
+ * only skips partial of hole area. However, it will be
+ * enough for most of the use cases.
+ */
+
+ if (skip_hole && data_pos < old_pos) {
+ data_pos = vfs_llseek(old_file, old_pos, SEEK_DATA);
+ if (data_pos > old_pos) {
+ hole_len = data_pos - old_pos;
+ len -= hole_len;
+ old_pos = new_pos = data_pos;
+ continue;
+ } else if (data_pos == -ENXIO) {
+ break;
+ } else if (data_pos < 0) {
+ skip_hole = false;
+ }
+ }
+
bytes = do_splice_direct(old_file, &old_pos,
new_file, &new_pos,
this_len, SPLICE_F_MOVE);
@@ -480,7 +517,7 @@ static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
}
inode_lock(temp->d_inode);
- if (c->metacopy)
+ if (S_ISREG(c->stat.mode))
err = ovl_set_size(temp, &c->stat);
if (!err)
err = ovl_set_attr(temp, &c->stat);