diff mbox

[2/2] btrfs-progs: convert: Make btrfs_reserved_ranges const

Message ID 20170316031831.28006-2-quwenruo@cn.fujitsu.com (mailing list archive)
State Accepted
Headers show

Commit Message

Qu Wenruo March 16, 2017, 3:18 a.m. UTC 
Since btrfs_reserved_ranges array is just used to store btrfs reserved
ranges, no one will nor should modify them at run time, make them static
and const will be better.

This also eliminates the use of immediate number 3.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
---
 convert/main.c      | 16 ++++++++--------
 convert/source-fs.c |  6 ------
 convert/source-fs.h |  8 ++++++--
 3 files changed, 14 insertions(+), 16 deletions(-)

Comments

David Sterba March 16, 2017, 4:33 p.m. UTC | #1 
On Thu, Mar 16, 2017 at 11:18:31AM +0800, Qu Wenruo wrote:
> Since btrfs_reserved_ranges array is just used to store btrfs reserved
> ranges, no one will nor should modify them at run time, make them static
> and const will be better.
> 
> This also eliminates the use of immediate number 3.

Adding const is fine, but you shouldn't define the structure inside
header, even as static. The number 3 needs to stay so we can use
ARRAY_SIZE.
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Qu Wenruo March 17, 2017, 12:35 a.m. UTC | #2 
At 03/17/2017 12:33 AM, David Sterba wrote:
> On Thu, Mar 16, 2017 at 11:18:31AM +0800, Qu Wenruo wrote:
>> Since btrfs_reserved_ranges array is just used to store btrfs reserved
>> ranges, no one will nor should modify them at run time, make them static
>> and const will be better.
>>
>> This also eliminates the use of immediate number 3.
>
> Adding const is fine, but you shouldn't define the structure inside
> header, even as static.

Any reason why we shouldn't define const static array in header?

Is extra .text segments usage the problem?

Thanks,
Qu

> The number 3 needs to stay so we can use
> ARRAY_SIZE.
>
>


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David Sterba March 27, 2017, 1:39 p.m. UTC | #3 
On Fri, Mar 17, 2017 at 08:35:01AM +0800, Qu Wenruo wrote:
> 
> 
> At 03/17/2017 12:33 AM, David Sterba wrote:
> > On Thu, Mar 16, 2017 at 11:18:31AM +0800, Qu Wenruo wrote:
> >> Since btrfs_reserved_ranges array is just used to store btrfs reserved
> >> ranges, no one will nor should modify them at run time, make them static
> >> and const will be better.
> >>
> >> This also eliminates the use of immediate number 3.
> >
> > Adding const is fine, but you shouldn't define the structure inside
> > header, even as static.
> 
> Any reason why we shouldn't define const static array in header?
> 
> Is extra .text segments usage the problem?

No, the problem is definition in a header.
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diff mbox

Patch

diff --git a/convert/main.c b/convert/main.c
index 73c9d889..96358c62 100644
--- a/convert/main.c
+++ b/convert/main.c
@@ -218,7 +218,7 @@  static int create_image_file_range(struct btrfs_trans_handle *trans,
 	 * migrate block will fail as there is already a file extent.
 	 */
 	for (i = 0; i < ARRAY_SIZE(btrfs_reserved_ranges); i++) {
-		struct simple_range *reserved = &btrfs_reserved_ranges[i];
+		const struct simple_range *reserved = &btrfs_reserved_ranges[i];
 
 		/*
 		 * |-- reserved --|
@@ -320,7 +320,7 @@  static int migrate_one_reserved_range(struct btrfs_trans_handle *trans,
 				      struct btrfs_root *root,
 				      struct cache_tree *used,
 				      struct btrfs_inode_item *inode, int fd,
-				      u64 ino, struct simple_range *range,
+				      u64 ino, const struct simple_range *range,
 				      u32 convert_flags)
 {
 	u64 cur_off = range->start;
@@ -423,7 +423,7 @@  static int migrate_reserved_ranges(struct btrfs_trans_handle *trans,
 	int ret = 0;
 
 	for (i = 0; i < ARRAY_SIZE(btrfs_reserved_ranges); i++) {
-		struct simple_range *range = &btrfs_reserved_ranges[i];
+		const struct simple_range *range = &btrfs_reserved_ranges[i];
 
 		if (range->start > total_bytes)
 			return ret;
@@ -609,7 +609,7 @@  static int wipe_reserved_ranges(struct cache_tree *tree, u64 min_stripe_size,
 	int ret;
 
 	for (i = 0; i < ARRAY_SIZE(btrfs_reserved_ranges); i++) {
-		struct simple_range *range = &btrfs_reserved_ranges[i];
+		const struct simple_range *range = &btrfs_reserved_ranges[i];
 
 		ret = wipe_one_reserved_range(tree, range->start, range->len,
 					      min_stripe_size, ensure_size);
@@ -1370,7 +1370,7 @@  static int read_reserved_ranges(struct btrfs_root *root, u64 ino,
 	int ret = 0;
 
 	for (i = 0; i < ARRAY_SIZE(btrfs_reserved_ranges); i++) {
-		struct simple_range *range = &btrfs_reserved_ranges[i];
+		const struct simple_range *range = &btrfs_reserved_ranges[i];
 
 		if (range->start + range->len >= total_bytes)
 			break;
@@ -1395,7 +1395,7 @@  static bool is_subset_of_reserved_ranges(u64 start, u64 len)
 	bool ret = false;
 
 	for (i = 0; i < ARRAY_SIZE(btrfs_reserved_ranges); i++) {
-		struct simple_range *range = &btrfs_reserved_ranges[i];
+		const struct simple_range *range = &btrfs_reserved_ranges[i];
 
 		if (start >= range->start && start + len <= range_end(range)) {
 			ret = true;
@@ -1620,7 +1620,7 @@  static int do_rollback(const char *devname)
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(btrfs_reserved_ranges); i++) {
-		struct simple_range *range = &btrfs_reserved_ranges[i];
+		const struct simple_range *range = &btrfs_reserved_ranges[i];
 
 		reserved_ranges[i] = calloc(1, range->len);
 		if (!reserved_ranges[i]) {
@@ -1730,7 +1730,7 @@  close_fs:
 
 	for (i = ARRAY_SIZE(btrfs_reserved_ranges) - 1; i >= 0; i--) {
 		u64 real_size;
-		struct simple_range *range = &btrfs_reserved_ranges[i];
+		const struct simple_range *range = &btrfs_reserved_ranges[i];
 
 		if (range_end(range) >= fsize)
 			continue;
diff --git a/convert/source-fs.c b/convert/source-fs.c
index 7cf515b0..8217c893 100644
--- a/convert/source-fs.c
+++ b/convert/source-fs.c
@@ -22,12 +22,6 @@ 
 #include "convert/common.h"
 #include "convert/source-fs.h"
 
-struct simple_range btrfs_reserved_ranges[3] = {
-	{ 0,			     SZ_1M },
-	{ BTRFS_SB_MIRROR_OFFSET(1), SZ_64K },
-	{ BTRFS_SB_MIRROR_OFFSET(2), SZ_64K }
-};
-
 static int intersect_with_sb(u64 bytenr, u64 num_bytes)
 {
 	int i;
diff --git a/convert/source-fs.h b/convert/source-fs.h
index 9f611150..7aabe96b 100644
--- a/convert/source-fs.h
+++ b/convert/source-fs.h
@@ -32,7 +32,11 @@  struct simple_range {
 	u64 len;
 };
 
-extern struct simple_range btrfs_reserved_ranges[3];
+static const struct simple_range btrfs_reserved_ranges[] = {
+	{ 0,			     SZ_1M },
+	{ BTRFS_SB_MIRROR_OFFSET(1), SZ_64K },
+	{ BTRFS_SB_MIRROR_OFFSET(2), SZ_64K }
+};
 
 struct task_info;
 
@@ -107,7 +111,7 @@  int record_file_blocks(struct blk_iterate_data *data,
  *
  * Get range end (exclusive)
  */
-static inline u64 range_end(struct simple_range *range)
+static inline u64 range_end(const struct simple_range *range)
 {
 	return (range->start + range->len);
 }