Re: [PATCH 01/11] btrfs: add macros for compression type and level
On Thu, Jan 31, 2019 at 05:00:10PM +0100, David Sterba wrote: > On Mon, Jan 28, 2019 at 04:24:27PM -0500, Dennis Zhou wrote: > > It is very easy to miss places that rely on a certain bitshifting for > > decyphering the type_level overloading. Make macros handle this instead. > > This encoding was a simple way to introduce the combined type and level > for zlib and it could certainly be improved. Either we'll use helpers > like you suggest or add a new structure that contains type and level as > members. That way we'd see where the level still matters and where the > just the type is ok. > > I haven't checked how much intrusive this would be, so that's for later > consideration. Some indirection can be removed for the .set_level > callbacks as it does not necessarily need to be a function so I'm > expecting that the code around that would be touched anyway. The only user of type_level is btrfs_compress_pages(). I do make an extra call to .set_level() there just to be safe, but that can be taken out as it should be correctly set from when we mounted. I envisioned .set_level() to be called when setting the compression level of the mount. This can be used in the same place if we were to add per-file compression levels too. I mention later, but an important part of .set_level() is to repurpose the meaning of 0 from meaning use the default to meaning use any workspace available. Thanks, Dennis
Re: [PATCH 01/11] btrfs: add macros for compression type and level
On Mon, Jan 28, 2019 at 04:24:27PM -0500, Dennis Zhou wrote: > It is very easy to miss places that rely on a certain bitshifting for > decyphering the type_level overloading. Make macros handle this instead. This encoding was a simple way to introduce the combined type and level for zlib and it could certainly be improved. Either we'll use helpers like you suggest or add a new structure that contains type and level as members. That way we'd see where the level still matters and where the just the type is ok. I haven't checked how much intrusive this would be, so that's for later consideration. Some indirection can be removed for the .set_level callbacks as it does not necessarily need to be a function so I'm expecting that the code around that would be touched anyway.
Re: [PATCH 01/11] btrfs: add macros for compression type and level
On Mon, Jan 28, 2019 at 04:24:27PM -0500, Dennis Zhou wrote:
> It is very easy to miss places that rely on a certain bitshifting for
> decyphering the type_level overloading. Make macros handle this instead.
>
> Signed-off-by: Dennis Zhou
> ---
> fs/btrfs/compression.c | 2 +-
> fs/btrfs/compression.h | 3 +++
> fs/btrfs/zlib.c| 2 +-
> 3 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
> index 548057630b69..586f95ac0aea 100644
> --- a/fs/btrfs/compression.c
> +++ b/fs/btrfs/compression.c
> @@ -1036,9 +1036,9 @@ int btrfs_compress_pages(unsigned int type_level,
> struct address_space *mapping,
>unsigned long *total_in,
>unsigned long *total_out)
> {
> + int type = BTRFS_COMPRESS_TYPE(type_level);
> struct list_head *workspace;
> int ret;
> - int type = type_level & 0xF;
>
> workspace = find_workspace(type);
>
> diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
> index ddda9b80bf20..69a9197dadc3 100644
> --- a/fs/btrfs/compression.h
> +++ b/fs/btrfs/compression.h
> @@ -25,6 +25,9 @@
>
> #define BTRFS_ZLIB_DEFAULT_LEVEL3
>
> +#define BTRFS_COMPRESS_TYPE(type_level) (type_level & 0xF)
> +#define BTRFS_COMPRESS_LEVEL(type_level) ((type_level & 0xF0) >> 4)
Nit: these can be inline functions rather than macros.
> struct compressed_bio {
> /* number of bios pending for this compressed extent */
> refcount_t pending_bios;
> diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
> index 970ff3e35bb3..1480b3eee306 100644
> --- a/fs/btrfs/zlib.c
> +++ b/fs/btrfs/zlib.c
> @@ -393,7 +393,7 @@ static int zlib_decompress(struct list_head *ws, unsigned
> char *data_in,
> static void zlib_set_level(struct list_head *ws, unsigned int type)
> {
> struct workspace *workspace = list_entry(ws, struct workspace, list);
> - unsigned level = (type & 0xF0) >> 4;
> + unsigned int level = BTRFS_COMPRESS_LEVEL(type);
>
> if (level > 9)
> level = 9;
> --
> 2.17.1
>
Re: [PATCH 01/11] btrfs: add macros for compression type and level
On Mon, Jan 28, 2019 at 04:24:27PM -0500, Dennis Zhou wrote: > It is very easy to miss places that rely on a certain bitshifting for > decyphering the type_level overloading. Make macros handle this instead. > > Signed-off-by: Dennis Zhou Reviewed-by: Josef Bacik Thanks, Josef
Re: [PATCH 01/11] btrfs: add macros for compression type and level
On 28.01.19 г. 23:24 ч., Dennis Zhou wrote: > It is very easy to miss places that rely on a certain bitshifting for > decyphering the type_level overloading. Make macros handle this instead. > > Signed-off-by: Dennis Zhou Reviewed-by: Nikolay Borisov
[PATCH 01/11] btrfs: add macros for compression type and level
It is very easy to miss places that rely on a certain bitshifting for
decyphering the type_level overloading. Make macros handle this instead.
Signed-off-by: Dennis Zhou
---
fs/btrfs/compression.c | 2 +-
fs/btrfs/compression.h | 3 +++
fs/btrfs/zlib.c| 2 +-
3 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 548057630b69..586f95ac0aea 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -1036,9 +1036,9 @@ int btrfs_compress_pages(unsigned int type_level, struct
address_space *mapping,
unsigned long *total_in,
unsigned long *total_out)
{
+ int type = BTRFS_COMPRESS_TYPE(type_level);
struct list_head *workspace;
int ret;
- int type = type_level & 0xF;
workspace = find_workspace(type);
diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
index ddda9b80bf20..69a9197dadc3 100644
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -25,6 +25,9 @@
#defineBTRFS_ZLIB_DEFAULT_LEVEL3
+#define BTRFS_COMPRESS_TYPE(type_level)(type_level & 0xF)
+#define BTRFS_COMPRESS_LEVEL(type_level) ((type_level & 0xF0) >> 4)
+
struct compressed_bio {
/* number of bios pending for this compressed extent */
refcount_t pending_bios;
diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
index 970ff3e35bb3..1480b3eee306 100644
--- a/fs/btrfs/zlib.c
+++ b/fs/btrfs/zlib.c
@@ -393,7 +393,7 @@ static int zlib_decompress(struct list_head *ws, unsigned
char *data_in,
static void zlib_set_level(struct list_head *ws, unsigned int type)
{
struct workspace *workspace = list_entry(ws, struct workspace, list);
- unsigned level = (type & 0xF0) >> 4;
+ unsigned int level = BTRFS_COMPRESS_LEVEL(type);
if (level > 9)
level = 9;
--
2.17.1
