[PATCH v3 07/11] e4defrag: Allow user who can use reserved blocks to defrag

[Kazuya Mio <k-mio@sx.jp.nec.com>]

Fix free blocks check for general users to use the reserved blocks because
they can use reserved blocks in the following cases:
- the users are specified by mount option resuid/resgid
- e4defrag has CAP_SYS_RESOURCE capability

Signed-off-by: Kazuya Mio <k-mio@sx.jp.nec.com>
---
 misc/e4defrag.c |   37 +++++++------------------------------
 1 file changed, 7 insertions(+), 30 deletions(-)
diff --git a/misc/e4defrag.c b/misc/e4defrag.c
index effd774..45e9b72 100644
--- a/misc/e4defrag.c
+++ b/misc/e4defrag.c
@@ -471,12 +471,15 @@ static int defrag_fadvise(int fd, struct move_extent defrag_data,
  * @fd:			defrag target file's descriptor.
  * @file:		file name.
  * @blk_count:		file blocks.
+ *
+ * Note that the users who cannot use the reserved blocks might pass this
+ * free space check though there is no free blocks except for reserved blocks.
+ * In this case, they can catch ENOSPC when donor file is created by fallocate
+ * in file_defrag(). So, it's no problem.
  */
 static int check_free_size(int fd, const char *file, ext4_fsblk_t blk_count)
 {
-	ext4_fsblk_t	free_blk_count;
 	struct statfs64	fsbuf;
-	uid_t		current_uid = getuid();
 
 	if (fstatfs64(fd, &fsbuf) < 0) {
 		if (mode_flag & DETAIL) {
@@ -487,16 +490,7 @@ static int check_free_size(int fd, const char *file, ext4_fsblk_t blk_count)
 		return -1;
 	}
 
-	/* Compute free space for root and normal user separately */
-	if (current_uid == ROOT_UID)
-		free_blk_count = fsbuf.f_bfree;
-	else
-		free_blk_count = fsbuf.f_bavail;
-
-	if (free_blk_count >= blk_count)
-		return 0;
-
-	return -ENOSPC;
+	return (fsbuf.f_bfree >= blk_count) ? 0 : -ENOSPC;
 }
 
 /*
@@ -768,23 +762,6 @@ static int get_exts_count(struct fiemap_extent_list *ext_list_head)
 	return ret;
 }
 
-/* get_file_blocks() -  Get total file blocks.
- *
- * @ext_list_head:	the extent list head of the target file
- */
-static ext4_fsblk_t get_file_blocks(struct fiemap_extent_list *ext_list_head)
-{
-	ext4_fsblk_t blk_count = 0;
-	struct fiemap_extent_list *ext_list_tmp = ext_list_head;
-
-	do {
-		blk_count += ext_list_tmp->data.len;
-		ext_list_tmp = ext_list_tmp->next;
-	} while (ext_list_tmp != ext_list_head);
-
-	return blk_count;
-}