diff options
| -rw-r--r-- | fs/overlayfs/copy_up.c | 41 |
1 files changed, 39 insertions, 2 deletions
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index b168c65666e2..9fc47c2e078d 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -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); |