From: Omar Sandoval <osandov@xxxxxx>
The implementation is fairly straightforward and looks a lot like
btrfs_rename().
Signed-off-by: Omar Sandoval <osandov@xxxxxx>
---
fs/btrfs/inode.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 55 insertions(+), 4 deletions(-)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 8e3a5a2..c903f6d 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -6566,15 +6566,20 @@ static int btrfs_create(struct inode *dir, struct dentry *dentry,
}
static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
- struct dentry *dentry)
+ struct dentry *dentry, unsigned int flags)
{
struct btrfs_trans_handle *trans = NULL;
+ unsigned int trans_num_items;
struct btrfs_root *root = BTRFS_I(dir)->root;
struct inode *inode = d_inode(old_dentry);
+ struct inode *new_inode = d_inode(dentry);
u64 index;
int err;
int drop_inode = 0;
+ if (flags & ~AT_REPLACE)
+ return -EINVAL;
+
/* do not allow sys_link's with other subvols of the same device */
if (root->objectid != BTRFS_I(inode)->root->objectid)
return -EXDEV;
@@ -6582,16 +6587,47 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
if (inode->i_nlink >= BTRFS_LINK_MAX)
return -EMLINK;
+ /* check for collisions, even if the name isn't there */
+ err = btrfs_check_dir_item_collision(root, dir->i_ino,
+ dentry->d_name.name,
+ dentry->d_name.len);
+ if (err) {
+ if (err == -EEXIST) {
+ if (WARN_ON(!new_inode))
+ return err;
+ } else {
+ return err;
+ }
+ }
+
+ /*
+ * we're using link to replace one file with another. Start IO on it now
+ * so we don't add too much work to the end of the transaction
+ */
+ if (new_inode && S_ISREG(inode->i_mode) && new_inode->i_size)
+ filemap_flush(inode->i_mapping);
+
err = btrfs_set_inode_index(dir, &index);
if (err)
goto fail;
/*
+ * For the source:
* 2 items for inode and inode ref
* 2 items for dir items
* 1 item for parent inode
+ *
+ * For the target:
+ * 1 for the possible orphan item
+ * 1 for the dir item
+ * 1 for the dir index
+ * 1 for the inode ref
+ * 1 for the inode
*/
- trans = btrfs_start_transaction(root, 5);
+ trans_num_items = 5;
+ if (new_inode)
+ trans_num_items += 5;
+ trans = btrfs_start_transaction(root, trans_num_items);
if (IS_ERR(trans)) {
err = PTR_ERR(trans);
trans = NULL;
@@ -6603,6 +6639,21 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
inc_nlink(inode);
inode_inc_iversion(inode);
inode->i_ctime = current_time(inode);
+
+ if (new_inode) {
+ inode_inc_iversion(new_inode);
+ new_inode->i_ctime = current_time(new_inode);
+ err = btrfs_unlink_inode(trans, root, dir, new_inode,
+ dentry->d_name.name,
+ dentry->d_name.len);
+ if (!err && new_inode->i_nlink == 0)
+ err = btrfs_orphan_add(trans, new_inode);
+ if (err) {
+ btrfs_abort_transaction(trans, err);
+ goto fail;
+ }
+ }
+
ihold(inode);
set_bit(BTRFS_INODE_COPY_EVERYTHING, &BTRFS_I(inode)->runtime_flags);
@@ -6624,7 +6675,7 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
if (err)
goto fail;
}
- d_instantiate(dentry, inode);
+ d_replace(dentry, inode);
btrfs_log_new_name(trans, inode, NULL, parent);
}
@@ -10570,7 +10621,7 @@ static const struct inode_operations btrfs_dir_inode_operations = {
.lookup = btrfs_lookup,
.create = btrfs_create,
.unlink = btrfs_unlink,
- .link = btrfs_link,
+ .link2 = btrfs_link,
.mkdir = btrfs_mkdir,
.rmdir = btrfs_rmdir,
.rename = btrfs_rename2,
--
2.10.2
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