It's safe and easy to do so, provided the ranges don't overlap.
Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
---
fs/btrfs/ioctl.c | 23 ++++++++++++++++-------
1 files changed, 16 insertions(+), 7 deletions(-)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 0b06a5c..8fcd671 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2223,8 +2223,6 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
* decompress into destination's address_space (the file offset
* may change, so source mapping won't do), then recompress (or
* otherwise reinsert) a subrange.
- * - allow ranges within the same file to be cloned (provided
- * they don't overlap)?
*/
/* the destination must be opened for writing */
@@ -2247,8 +2245,6 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
src = src_file->f_dentry->d_inode;
ret = -EINVAL;
- if (src == inode)
- goto out_fput;
/* the src must be open for reading */
if (!(src_file->f_mode & FMODE_READ))
@@ -2282,9 +2278,11 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
if (inode < src) {
mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT);
mutex_lock_nested(&src->i_mutex, I_MUTEX_CHILD);
- } else {
+ } else if (inode > src) {
mutex_lock_nested(&src->i_mutex, I_MUTEX_PARENT);
mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD);
+ } else {
+ mutex_lock(&inode->i_mutex);
}
/* determine range to clone */
@@ -2302,6 +2300,13 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
!IS_ALIGNED(destoff, bs))
goto out_unlock;
+ /*
+ * allow ranges within the same file to be cloned only if
+ * they don't overlap
+ */
+ if (src == inode && !(off + len <= destoff || destoff + len <= off))
+ goto out_unlock;
+
if (destoff > inode->i_size) {
ret = btrfs_cont_expand(inode, inode->i_size, destoff);
if (ret)
@@ -2543,8 +2548,12 @@ out:
btrfs_release_path(path);
unlock_extent(&BTRFS_I(src)->io_tree, off, off+len, GFP_NOFS);
out_unlock:
- mutex_unlock(&src->i_mutex);
- mutex_unlock(&inode->i_mutex);
+ if (src != inode) {
+ mutex_unlock(&src->i_mutex);
+ mutex_unlock(&inode->i_mutex);
+ } else {
+ mutex_unlock(&inode->i_mutex);
+ }
vfree(buf);
btrfs_free_path(path);
out_fput:
--
1.7.3.1
--
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