[PATCH 0/4] variables fixes in compression.c

[PATCH 0/4] variables fixes in compression.c

[Anand Jain]

Patch (btrfs: reduce compressed_bio member's types) reduced the
size to unsigned int as in [1]. Fix its cascading effects here.
And one stale comment in the patch 4/4.

[1]
-       unsigned long len;
+       unsigned int len;

-       int compress_type;
+       u8 compress_type;

-       unsigned long nr_pages;
+       unsigned int nr_pages;

-       unsigned long compressed_len;
+       unsigned int compressed_len;

-       int errors;
+       u8 errors;

As shown in [2], we set the max compressable block size to 128K. So
struct async_extent can reduce some of its members to unsigned int as
well.

[2]
static noinline int compress_file_range(struct async_chunk *async_chunk)
::
  617         total_compressed = min_t(unsigned long, total_compressed,
  618                         BTRFS_MAX_UNCOMPRESSED);

But changes touches too many places, and my first attempt to fix
is unsatisfactory to me, so I am just sending the changes limited to the
file compression.c.

Anand Jain (4):
  btrfs: optimize users of members of the struct compressed_bio
  btrfs: optimize variables size in btrfs_submit_compressed_read
  btrfs: optimize variables size in btrfs_submit_compressed_write
  btrfs: fix comment about max_out in btrfs_compress_pages

 fs/btrfs/compression.c | 21 +++++++++------------
 fs/btrfs/compression.h |  6 +++---
 2 files changed, 12 insertions(+), 15 deletions(-)

-- 
2.30.2

[PATCH 1/4] btrfs: reduce the variable size to fit nr_pages

[Anand Jain]

Patch (btrfs: reduce compressed_bio member's types) reduced the 
@nr_pages size to unsigned int, its cascading effects are fixed here.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/compression.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 7bd7cae51dbf..e10041af8476 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -149,7 +149,7 @@ static int check_compressed_csum(struct btrfs_inode *inode, struct bio *bio,
 	const u32 csum_size = fs_info->csum_size;
 	const u32 sectorsize = fs_info->sectorsize;
 	struct page *page;
-	unsigned long i;
+	unsigned int i;
 	char *kaddr;
 	u8 csum[BTRFS_CSUM_SIZE];
 	struct compressed_bio *cb = bio->bi_private;
@@ -208,7 +208,7 @@ static void end_compressed_bio_read(struct bio *bio)
 	struct compressed_bio *cb = bio->bi_private;
 	struct inode *inode;
 	struct page *page;
-	unsigned long index;
+	unsigned int index;
 	unsigned int mirror = btrfs_io_bio(bio)->mirror_num;
 	int ret = 0;
 
@@ -334,7 +334,7 @@ static void end_compressed_bio_write(struct bio *bio)
 	struct compressed_bio *cb = bio->bi_private;
 	struct inode *inode;
 	struct page *page;
-	unsigned long index;
+	unsigned int index;
 
 	if (bio->bi_status)
 		cb->errors = 1;
-- 
2.30.2

[PATCH 2/4] btrfs: optimize variables size in btrfs_submit_compressed_read

[Anand Jain]

Patch (btrfs: reduce compressed_bio member's types) reduced some
member's size. Declare the variables @compressed_len, @nr_pages and
@pg_index size as an unsigned int in the function
btrfs_submit_compressed_read.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/compression.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index e10041af8476..c1432a58f378 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -667,9 +667,9 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 	struct extent_map_tree *em_tree;
 	struct compressed_bio *cb;
-	unsigned long compressed_len;
-	unsigned long nr_pages;
-	unsigned long pg_index;
+	unsigned int compressed_len;
+	unsigned int nr_pages;
+	unsigned int pg_index;
 	struct page *page;
 	struct bio *comp_bio;
 	u64 cur_disk_byte = bio->bi_iter.bi_sector << 9;
-- 
2.30.2

[PATCH 3/4] btrfs: optimize variables size in btrfs_submit_compressed_write

[Anand Jain]

Patch (btrfs: reduce compressed_bio member's types) reduced some
member's size. Function arguments @len, @compressed_len and @nr_pages
can be declared as unsigned int.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/compression.c | 6 +++---
 fs/btrfs/compression.h | 6 +++---
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index c1432a58f378..c523f384bd1a 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -385,10 +385,10 @@ static void end_compressed_bio_write(struct bio *bio)
  * the end io hooks.
  */
 blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
-				 unsigned long len, u64 disk_start,
-				 unsigned long compressed_len,
+				 unsigned int len, u64 disk_start,
+				 unsigned int compressed_len,
 				 struct page **compressed_pages,
-				 unsigned long nr_pages,
+				 unsigned int nr_pages,
 				 unsigned int write_flags,
 				 struct cgroup_subsys_state *blkcg_css)
 {
diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
index 00d8439048c9..c359f20920d0 100644
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -91,10 +91,10 @@ int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start,
 			      struct bio *bio);
 
 blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
-				  unsigned long len, u64 disk_start,
-				  unsigned long compressed_len,
+				  unsigned int len, u64 disk_start,
+				  unsigned int compressed_len,
 				  struct page **compressed_pages,
-				  unsigned long nr_pages,
+				  unsigned int nr_pages,
 				  unsigned int write_flags,
 				  struct cgroup_subsys_state *blkcg_css);
 blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
-- 
2.30.2

[PATCH 4/4] btrfs: fix comment about max_out in btrfs_compress_pages

[Anand Jain]

Commit e5d74902362f (btrfs: derive maximum output size in the compression
implementation) removed @max_out argument in btrfs_compress_pages() but
its comment remained, remove it.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/compression.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index c523f384bd1a..35ca49893803 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -1192,9 +1192,6 @@ static unsigned int btrfs_compress_set_level(int type, unsigned level)
  *
  * @total_out is an in/out parameter, must be set to the input length and will
  * be also used to return the total number of compressed bytes
- *
- * @max_out tells us the max number of bytes that we're allowed to
- * stuff into pages
  */
 int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,
 			 u64 start, struct page **pages,
-- 
2.30.2

Re: [PATCH 0/4] variables fixes in compression.c

[David Sterba]

On Sat, May 29, 2021 at 05:48:32PM +0800, Anand Jain wrote:
> Patch (btrfs: reduce compressed_bio member's types) reduced the
> size to unsigned int as in [1]. Fix its cascading effects here.
> And one stale comment in the patch 4/4.
> 
> [1]
> -       unsigned long len;
> +       unsigned int len;
> 
> -       int compress_type;
> +       u8 compress_type;
> 
> -       unsigned long nr_pages;
> +       unsigned int nr_pages;
> 
> -       unsigned long compressed_len;
> +       unsigned int compressed_len;
> 
> -       int errors;
> +       u8 errors;
> 
> As shown in [2], we set the max compressable block size to 128K. So
> struct async_extent can reduce some of its members to unsigned int as
> well.
> 
> [2]
> static noinline int compress_file_range(struct async_chunk *async_chunk)
> ::
>   617         total_compressed = min_t(unsigned long, total_compressed,
>   618                         BTRFS_MAX_UNCOMPRESSED);
> 
> But changes touches too many places, and my first attempt to fix
> is unsatisfactory to me, so I am just sending the changes limited to the
> file compression.c.

That's fin. As long as a patch does one change (possibly cascading to
more places) it should be doable step by step.

> Anand Jain (4):
>   btrfs: optimize users of members of the struct compressed_bio
>   btrfs: optimize variables size in btrfs_submit_compressed_read
>   btrfs: optimize variables size in btrfs_submit_compressed_write
>   btrfs: fix comment about max_out in btrfs_compress_pages

Added to misc-next, thanks.