btrfs: fix metadata extent leak after failure to create subvolume

[mirror_ubuntu-focal-kernel.git] / fs / read_write.c

diff --git a/fs/read_write.c b/fs/read_write.c
index 5bbf587f5bc135485d21331039a8085f1e0500f7..9f5ff742f870e53ee9d4b4ff55b5a556b2cd1338 100644 (file)
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -468,6 +468,7 @@ ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
 
        return ret;
 }
+EXPORT_SYMBOL_GPL(vfs_read);
 
 static ssize_t new_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
 {
@@ -498,6 +499,30 @@ static ssize_t __vfs_write(struct file *file, const char __user *p,
                return -EINVAL;
 }
 
+vfs_readf_t vfs_readf(struct file *file)
+{
+       const struct file_operations *fop = file->f_op;
+
+       if (fop->read)
+               return fop->read;
+       if (fop->read_iter)
+               return new_sync_read;
+       return ERR_PTR(-ENOSYS); /* doesn't have ->read(|_iter)() op */
+}
+EXPORT_SYMBOL_GPL(vfs_readf);
+
+vfs_writef_t vfs_writef(struct file *file)
+{
+       const struct file_operations *fop = file->f_op;
+
+       if (fop->write)
+               return fop->write;
+       if (fop->write_iter)
+               return new_sync_write;
+       return ERR_PTR(-ENOSYS); /* doesn't have ->write(|_iter)() op */
+}
+EXPORT_SYMBOL_GPL(vfs_writef);
+
 ssize_t __kernel_write(struct file *file, const void *buf, size_t count, loff_t *pos)
 {
        mm_segment_t old_fs;
@@ -566,6 +591,7 @@ ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_
 
        return ret;
 }
+EXPORT_SYMBOL_GPL(vfs_write);
 
 /* file_ppos returns &file->f_pos or NULL if file is stream */
 static inline loff_t *file_ppos(struct file *file)
@@ -1777,10 +1803,9 @@ static int remap_verify_area(struct file *file, loff_t pos, loff_t len,
  * else.  Assume that the offsets have already been checked for block
  * alignment.
  *
- * For deduplication we always scale down to the previous block because we
- * can't meaningfully compare post-EOF contents.
- *
- * For clone we only link a partial EOF block above the destination file's EOF.
+ * For clone we only link a partial EOF block above or at the destination file's
+ * EOF.  For deduplication we accept a partial EOF block only if it ends at the
+ * destination file's EOF (can not link it into the middle of a file).
  *
  * Shorten the request if possible.
  */
@@ -1796,8 +1821,7 @@ static int generic_remap_check_len(struct inode *inode_in,
        if ((*len & blkmask) == 0)
                return 0;
 
-       if ((remap_flags & REMAP_FILE_DEDUP) ||
-           pos_out + *len < i_size_read(inode_out))
+       if (pos_out + *len < i_size_read(inode_out))
                new_len &= ~blkmask;
 
        if (new_len == *len)