* [PATCH] fs: ufs: Convert ufs_set_de_type to use lookup table
@ 2018-04-03 8:59 Phillip Potter
0 siblings, 0 replies; 5+ messages in thread
From: Phillip Potter @ 2018-04-03 8:59 UTC (permalink / raw)
To: dushistov; +Cc: linux-kernel, linux-fsdevel
Modify ufs_set_de_type function in fs/ufs/util.h to use a lookup
table rather than a switch statement, as per the TODO comment.
Signed-off-by: Phillip Potter <phil@philpotter.co.uk>
---
fs/ufs/util.h | 50 ++++++++++++++++++++++----------------------------
1 file changed, 22 insertions(+), 28 deletions(-)
diff --git a/fs/ufs/util.h b/fs/ufs/util.h
index 1907be6d5808..1edf4c6454e3 100644
--- a/fs/ufs/util.h
+++ b/fs/ufs/util.h
@@ -155,37 +155,31 @@ ufs_set_de_namlen(struct super_block *sb, struct ufs_dir_entry *de, u16 value)
static inline void
ufs_set_de_type(struct super_block *sb, struct ufs_dir_entry *de, int mode)
{
+ /* type lookup table, DT_UNKNOWN is default type if no case holds */
+ const int mode_table[] = {
+ DT_UNKNOWN,
+ DT_FIFO, /* mode & S_IFMT == S_IFIFO case */
+ DT_CHR, /* mode & S_IFMT == S_IFCHR case */
+ DT_UNKNOWN,
+ DT_DIR, /* mode & S_IFMT == S_IFDIR case */
+ DT_UNKNOWN,
+ DT_BLK, /* mode & S_IFMT == S_IFBLK case */
+ DT_UNKNOWN,
+ DT_REG, /* mode & S_IFMT == S_IFREG case */
+ DT_UNKNOWN,
+ DT_LNK, /* mode & S_IFMT == S_IFLNK case */
+ DT_UNKNOWN,
+ DT_SOCK, /* mode & S_IFMT == S_IFSOCK case */
+ DT_UNKNOWN,
+ DT_UNKNOWN,
+ DT_UNKNOWN
+ };
+
if ((UFS_SB(sb)->s_flags & UFS_DE_MASK) != UFS_DE_44BSD)
return;
- /*
- * TODO turn this into a table lookup
- */
- switch (mode & S_IFMT) {
- case S_IFSOCK:
- de->d_u.d_44.d_type = DT_SOCK;
- break;
- case S_IFLNK:
- de->d_u.d_44.d_type = DT_LNK;
- break;
- case S_IFREG:
- de->d_u.d_44.d_type = DT_REG;
- break;
- case S_IFBLK:
- de->d_u.d_44.d_type = DT_BLK;
- break;
- case S_IFDIR:
- de->d_u.d_44.d_type = DT_DIR;
- break;
- case S_IFCHR:
- de->d_u.d_44.d_type = DT_CHR;
- break;
- case S_IFIFO:
- de->d_u.d_44.d_type = DT_FIFO;
- break;
- default:
- de->d_u.d_44.d_type = DT_UNKNOWN;
- }
+ /* shift (mode & S_IFMT) right 12 bits to index into table */
+ de->d_u.d_44.d_type = mode_table[(mode & S_IFMT) >> 12];
}
static inline u32
--
2.14.3
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] fs: ufs: Convert ufs_set_de_type to use lookup table
2018-10-02 2:28 ` Al Viro
@ 2018-10-02 8:31 ` Phillip Potter
0 siblings, 0 replies; 5+ messages in thread
From: Phillip Potter @ 2018-10-02 8:31 UTC (permalink / raw)
To: Al Viro; +Cc: dushistov, linux-kernel
On Tue, Oct 02, 2018 at 03:28:14AM +0100, Al Viro wrote:
> On Mon, Oct 01, 2018 at 04:33:10PM +0100, Phillip Potter wrote:
> > Modify ufs_set_de_type function in fs/ufs/util.h to use a lookup
> > table rather than a switch statement, as per the TODO comment.
>
> Brittle, that... Something like fs/ext2/dir.c approach (that is,
> #define S_SHIFT 12
> static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = {
> [S_IFREG >> S_SHIFT] = EXT2_FT_REG_FILE,
> [S_IFDIR >> S_SHIFT] = EXT2_FT_DIR,
> [S_IFCHR >> S_SHIFT] = EXT2_FT_CHRDEV,
> [S_IFBLK >> S_SHIFT] = EXT2_FT_BLKDEV,
> [S_IFIFO >> S_SHIFT] = EXT2_FT_FIFO,
> [S_IFSOCK >> S_SHIFT] = EXT2_FT_SOCK,
> [S_IFLNK >> S_SHIFT] = EXT2_FT_SYMLINK,
> };
> in there) would be saner, IMO. Note that DT_UNKNOWN is zero, so the
> array elements lacking an explicit initializer will end up with that.
>
> What's more, the values are ->i_mode >> 12 or 0, depending upon the
> value being valid. And since the upper layers do validate the type,
> I'd consider simply using (inode->i_mode & S_IFMT) >> 12 there.
> Unlike ext2, ufs stores straight bits 12..15 there (ext2 uses an
> enum with sequential values instead; e.g. regular files are encoded
> as 1 there, not 8 as on ufs)...
Dear Al,
Thank you for taking time to offer your feedback, I really appreciate
it. I will rework this patch this evening and resubmit.
Regards,
Phil
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] fs: ufs: Convert ufs_set_de_type to use lookup table
2018-10-01 15:33 Phillip Potter
@ 2018-10-02 2:28 ` Al Viro
2018-10-02 8:31 ` Phillip Potter
0 siblings, 1 reply; 5+ messages in thread
From: Al Viro @ 2018-10-02 2:28 UTC (permalink / raw)
To: Phillip Potter; +Cc: dushistov, linux-kernel
On Mon, Oct 01, 2018 at 04:33:10PM +0100, Phillip Potter wrote:
> Modify ufs_set_de_type function in fs/ufs/util.h to use a lookup
> table rather than a switch statement, as per the TODO comment.
Brittle, that... Something like fs/ext2/dir.c approach (that is,
#define S_SHIFT 12
static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = {
[S_IFREG >> S_SHIFT] = EXT2_FT_REG_FILE,
[S_IFDIR >> S_SHIFT] = EXT2_FT_DIR,
[S_IFCHR >> S_SHIFT] = EXT2_FT_CHRDEV,
[S_IFBLK >> S_SHIFT] = EXT2_FT_BLKDEV,
[S_IFIFO >> S_SHIFT] = EXT2_FT_FIFO,
[S_IFSOCK >> S_SHIFT] = EXT2_FT_SOCK,
[S_IFLNK >> S_SHIFT] = EXT2_FT_SYMLINK,
};
in there) would be saner, IMO. Note that DT_UNKNOWN is zero, so the
array elements lacking an explicit initializer will end up with that.
What's more, the values are ->i_mode >> 12 or 0, depending upon the
value being valid. And since the upper layers do validate the type,
I'd consider simply using (inode->i_mode & S_IFMT) >> 12 there.
Unlike ext2, ufs stores straight bits 12..15 there (ext2 uses an
enum with sequential values instead; e.g. regular files are encoded
as 1 there, not 8 as on ufs)...
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH] fs: ufs: Convert ufs_set_de_type to use lookup table
@ 2018-10-01 15:33 Phillip Potter
2018-10-02 2:28 ` Al Viro
0 siblings, 1 reply; 5+ messages in thread
From: Phillip Potter @ 2018-10-01 15:33 UTC (permalink / raw)
To: dushistov; +Cc: linux-kernel
Modify ufs_set_de_type function in fs/ufs/util.h to use a lookup
table rather than a switch statement, as per the TODO comment.
Signed-off-by: Phillip Potter <phil@philpotter.co.uk>
---
diff --git a/fs/ufs/util.h b/fs/ufs/util.h
index 1907be6d5808..1edf4c6454e3 100644
--- a/fs/ufs/util.h
+++ b/fs/ufs/util.h
@@ -155,37 +155,31 @@ ufs_set_de_namlen(struct super_block *sb, struct ufs_dir_entry *de, u16 value)
static inline void
ufs_set_de_type(struct super_block *sb, struct ufs_dir_entry *de, int mode)
{
+ /* type lookup table, DT_UNKNOWN is default type if no case holds */
+ const int mode_table[] = {
+ DT_UNKNOWN,
+ DT_FIFO, /* mode & S_IFMT == S_IFIFO case */
+ DT_CHR, /* mode & S_IFMT == S_IFCHR case */
+ DT_UNKNOWN,
+ DT_DIR, /* mode & S_IFMT == S_IFDIR case */
+ DT_UNKNOWN,
+ DT_BLK, /* mode & S_IFMT == S_IFBLK case */
+ DT_UNKNOWN,
+ DT_REG, /* mode & S_IFMT == S_IFREG case */
+ DT_UNKNOWN,
+ DT_LNK, /* mode & S_IFMT == S_IFLNK case */
+ DT_UNKNOWN,
+ DT_SOCK, /* mode & S_IFMT == S_IFSOCK case */
+ DT_UNKNOWN,
+ DT_UNKNOWN,
+ DT_UNKNOWN
+ };
+
if ((UFS_SB(sb)->s_flags & UFS_DE_MASK) != UFS_DE_44BSD)
return;
- /*
- * TODO turn this into a table lookup
- */
- switch (mode & S_IFMT) {
- case S_IFSOCK:
- de->d_u.d_44.d_type = DT_SOCK;
- break;
- case S_IFLNK:
- de->d_u.d_44.d_type = DT_LNK;
- break;
- case S_IFREG:
- de->d_u.d_44.d_type = DT_REG;
- break;
- case S_IFBLK:
- de->d_u.d_44.d_type = DT_BLK;
- break;
- case S_IFDIR:
- de->d_u.d_44.d_type = DT_DIR;
- break;
- case S_IFCHR:
- de->d_u.d_44.d_type = DT_CHR;
- break;
- case S_IFIFO:
- de->d_u.d_44.d_type = DT_FIFO;
- break;
- default:
- de->d_u.d_44.d_type = DT_UNKNOWN;
- }
+ /* shift (mode & S_IFMT) right 12 bits to index into table */
+ de->d_u.d_44.d_type = mode_table[(mode & S_IFMT) >> 12];
}
static inline u32
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH] fs: ufs: Convert ufs_set_de_type to use lookup table
@ 2018-03-18 20:56 Phillip Potter
0 siblings, 0 replies; 5+ messages in thread
From: Phillip Potter @ 2018-03-18 20:56 UTC (permalink / raw)
To: dushistov; +Cc: linux-kernel
Modify ufs_set_de_type function in fs/ufs/util.h to use a lookup
table rather than a switch statement, as per the TODO comment.
Signed-off-by: Phillip Potter <phil@philpotter.co.uk>
---
fs/ufs/util.h | 50 ++++++++++++++++++++++----------------------------
1 file changed, 22 insertions(+), 28 deletions(-)
diff --git a/fs/ufs/util.h b/fs/ufs/util.h
index 1907be6d5808..1edf4c6454e3 100644
--- a/fs/ufs/util.h
+++ b/fs/ufs/util.h
@@ -155,37 +155,31 @@ ufs_set_de_namlen(struct super_block *sb, struct ufs_dir_entry *de, u16 value)
static inline void
ufs_set_de_type(struct super_block *sb, struct ufs_dir_entry *de, int mode)
{
+ /* type lookup table, DT_UNKNOWN is default type if no case holds */
+ const int mode_table[] = {
+ DT_UNKNOWN,
+ DT_FIFO, /* mode & S_IFMT == S_IFIFO case */
+ DT_CHR, /* mode & S_IFMT == S_IFCHR case */
+ DT_UNKNOWN,
+ DT_DIR, /* mode & S_IFMT == S_IFDIR case */
+ DT_UNKNOWN,
+ DT_BLK, /* mode & S_IFMT == S_IFBLK case */
+ DT_UNKNOWN,
+ DT_REG, /* mode & S_IFMT == S_IFREG case */
+ DT_UNKNOWN,
+ DT_LNK, /* mode & S_IFMT == S_IFLNK case */
+ DT_UNKNOWN,
+ DT_SOCK, /* mode & S_IFMT == S_IFSOCK case */
+ DT_UNKNOWN,
+ DT_UNKNOWN,
+ DT_UNKNOWN
+ };
+
if ((UFS_SB(sb)->s_flags & UFS_DE_MASK) != UFS_DE_44BSD)
return;
- /*
- * TODO turn this into a table lookup
- */
- switch (mode & S_IFMT) {
- case S_IFSOCK:
- de->d_u.d_44.d_type = DT_SOCK;
- break;
- case S_IFLNK:
- de->d_u.d_44.d_type = DT_LNK;
- break;
- case S_IFREG:
- de->d_u.d_44.d_type = DT_REG;
- break;
- case S_IFBLK:
- de->d_u.d_44.d_type = DT_BLK;
- break;
- case S_IFDIR:
- de->d_u.d_44.d_type = DT_DIR;
- break;
- case S_IFCHR:
- de->d_u.d_44.d_type = DT_CHR;
- break;
- case S_IFIFO:
- de->d_u.d_44.d_type = DT_FIFO;
- break;
- default:
- de->d_u.d_44.d_type = DT_UNKNOWN;
- }
+ /* shift (mode & S_IFMT) right 12 bits to index into table */
+ de->d_u.d_44.d_type = mode_table[(mode & S_IFMT) >> 12];
}
static inline u32
--
2.14.3
^ permalink raw reply related [flat|nested] 5+ messages in thread
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2018-10-01 15:33 Phillip Potter
2018-10-02 2:28 ` Al Viro
2018-10-02 8:31 ` Phillip Potter
2018-03-18 20:56 Phillip Potter
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