| Message ID | 20201228234955.190858-5-dgilbert@interlog.com |
|---|---|
| State | New |
| Headers | show |
| Series | scatterlist: add new capabilities | expand |
On Mon, Dec 28, 2020 at 06:49:55PM -0500, Douglas Gilbert wrote: > The existing sg_zero_buffer() function is a bit restrictive. For > example protection information (PI) blocks are usually initialized > to 0xff bytes. As its name suggests sgl_memset() is modelled on > memset(). One difference is the type of the val argument which is > u8 rather than int. Plus it returns the number of bytes (over)written. > > Change implementation of sg_zero_buffer() to call this new function. > > Reviewed-by: Bodo Stroesser <bostroesser@gmail.com> > Signed-off-by: Douglas Gilbert <dgilbert@interlog.com> > include/linux/scatterlist.h | 3 ++ > lib/scatterlist.c | 65 +++++++++++++++++++++++++------------ > 2 files changed, 48 insertions(+), 20 deletions(-) > > diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h > index 71be65f9ebb5..70d3f1f73df1 100644 > +++ b/include/linux/scatterlist.h > @@ -333,6 +333,9 @@ bool sgl_compare_sgl_idx(struct scatterlist *x_sgl, unsigned int x_nents, off_t > struct scatterlist *y_sgl, unsigned int y_nents, off_t y_skip, > size_t n_bytes, size_t *miscompare_idx); > > +size_t sgl_memset(struct scatterlist *sgl, unsigned int nents, off_t skip, > + u8 val, size_t n_bytes); > + > /* > * Maximum number of entries that will be allocated in one piece, if > * a list larger than this is required then chaining will be utilized. > diff --git a/lib/scatterlist.c b/lib/scatterlist.c > index 9332365e7eb6..f06614a880c8 100644 > +++ b/lib/scatterlist.c > @@ -1038,26 +1038,7 @@ EXPORT_SYMBOL(sg_pcopy_to_buffer); > size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents, > size_t buflen, off_t skip) > { > - unsigned int offset = 0; > - struct sg_mapping_iter miter; > - unsigned int sg_flags = SG_MITER_ATOMIC | SG_MITER_TO_SG; > - > - sg_miter_start(&miter, sgl, nents, sg_flags); > - > - if (!sg_miter_skip(&miter, skip)) > - return false; > - > - while (offset < buflen && sg_miter_next(&miter)) { > - unsigned int len; > - > - len = min(miter.length, buflen - offset); > - memset(miter.addr, 0, len); > - > - offset += len; > - } > - > - sg_miter_stop(&miter); > - return offset; > + return sgl_memset(sgl, nents, skip, 0, buflen); > } > EXPORT_SYMBOL(sg_zero_buffer); May as well make this one liner a static inline in the header. Just rename this function to sgl_memset so the diff is clearer Jason
On 2021-01-07 12:46 p.m., Jason Gunthorpe wrote: > On Mon, Dec 28, 2020 at 06:49:55PM -0500, Douglas Gilbert wrote: >> The existing sg_zero_buffer() function is a bit restrictive. For >> example protection information (PI) blocks are usually initialized >> to 0xff bytes. As its name suggests sgl_memset() is modelled on >> memset(). One difference is the type of the val argument which is >> u8 rather than int. Plus it returns the number of bytes (over)written. >> >> Change implementation of sg_zero_buffer() to call this new function. >> >> Reviewed-by: Bodo Stroesser <bostroesser@gmail.com> >> Signed-off-by: Douglas Gilbert <dgilbert@interlog.com> >> include/linux/scatterlist.h | 3 ++ >> lib/scatterlist.c | 65 +++++++++++++++++++++++++------------ >> 2 files changed, 48 insertions(+), 20 deletions(-) >> >> diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h >> index 71be65f9ebb5..70d3f1f73df1 100644 >> +++ b/include/linux/scatterlist.h >> @@ -333,6 +333,9 @@ bool sgl_compare_sgl_idx(struct scatterlist *x_sgl, unsigned int x_nents, off_t >> struct scatterlist *y_sgl, unsigned int y_nents, off_t y_skip, >> size_t n_bytes, size_t *miscompare_idx); >> >> +size_t sgl_memset(struct scatterlist *sgl, unsigned int nents, off_t skip, >> + u8 val, size_t n_bytes); >> + >> /* >> * Maximum number of entries that will be allocated in one piece, if >> * a list larger than this is required then chaining will be utilized. >> diff --git a/lib/scatterlist.c b/lib/scatterlist.c >> index 9332365e7eb6..f06614a880c8 100644 >> +++ b/lib/scatterlist.c >> @@ -1038,26 +1038,7 @@ EXPORT_SYMBOL(sg_pcopy_to_buffer); >> size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents, >> size_t buflen, off_t skip) >> { >> - unsigned int offset = 0; >> - struct sg_mapping_iter miter; >> - unsigned int sg_flags = SG_MITER_ATOMIC | SG_MITER_TO_SG; >> - >> - sg_miter_start(&miter, sgl, nents, sg_flags); >> - >> - if (!sg_miter_skip(&miter, skip)) >> - return false; >> - >> - while (offset < buflen && sg_miter_next(&miter)) { >> - unsigned int len; >> - >> - len = min(miter.length, buflen - offset); >> - memset(miter.addr, 0, len); >> - >> - offset += len; >> - } >> - >> - sg_miter_stop(&miter); >> - return offset; >> + return sgl_memset(sgl, nents, skip, 0, buflen); >> } >> EXPORT_SYMBOL(sg_zero_buffer); > > May as well make this one liner a static inline in the header. Just > rename this function to sgl_memset so the diff is clearer Yes, fine. I can roll a new version. Doug Gilbert
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index 71be65f9ebb5..70d3f1f73df1 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -333,6 +333,9 @@ bool sgl_compare_sgl_idx(struct scatterlist *x_sgl, unsigned int x_nents, off_t struct scatterlist *y_sgl, unsigned int y_nents, off_t y_skip, size_t n_bytes, size_t *miscompare_idx); +size_t sgl_memset(struct scatterlist *sgl, unsigned int nents, off_t skip, + u8 val, size_t n_bytes); + /* * Maximum number of entries that will be allocated in one piece, if * a list larger than this is required then chaining will be utilized. diff --git a/lib/scatterlist.c b/lib/scatterlist.c index 9332365e7eb6..f06614a880c8 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -1038,26 +1038,7 @@ EXPORT_SYMBOL(sg_pcopy_to_buffer); size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents, size_t buflen, off_t skip) { - unsigned int offset = 0; - struct sg_mapping_iter miter; - unsigned int sg_flags = SG_MITER_ATOMIC | SG_MITER_TO_SG; - - sg_miter_start(&miter, sgl, nents, sg_flags); - - if (!sg_miter_skip(&miter, skip)) - return false; - - while (offset < buflen && sg_miter_next(&miter)) { - unsigned int len; - - len = min(miter.length, buflen - offset); - memset(miter.addr, 0, len); - - offset += len; - } - - sg_miter_stop(&miter); - return offset; + return sgl_memset(sgl, nents, skip, 0, buflen); } EXPORT_SYMBOL(sg_zero_buffer); @@ -1243,3 +1224,47 @@ bool sgl_compare_sgl(struct scatterlist *x_sgl, unsigned int x_nents, off_t x_sk return sgl_compare_sgl_idx(x_sgl, x_nents, x_skip, y_sgl, y_nents, y_skip, n_bytes, NULL); } EXPORT_SYMBOL(sgl_compare_sgl); + +/** + * sgl_memset - set byte 'val' up to n_bytes times on SG list + * @sgl: The SG list + * @nents: Number of SG entries in sgl + * @skip: Number of bytes to skip before starting + * @val: byte value to write to sgl + * @n_bytes: The (maximum) number of bytes to modify + * + * Returns: + * The number of bytes written. + * + * Notes: + * Stops writing if either sgl or n_bytes is exhausted. If n_bytes is + * set SIZE_MAX then val will be written to each byte until the end + * of sgl. + * + * The notes in sgl_copy_sgl() about large sgl_s _applies here as well. + * + **/ +size_t sgl_memset(struct scatterlist *sgl, unsigned int nents, off_t skip, + u8 val, size_t n_bytes) +{ + size_t offset = 0; + size_t len; + struct sg_mapping_iter miter; + + if (n_bytes == 0) + return 0; + sg_miter_start(&miter, sgl, nents, SG_MITER_ATOMIC | SG_MITER_TO_SG); + if (!sg_miter_skip(&miter, skip)) + goto fini; + + while ((offset < n_bytes) && sg_miter_next(&miter)) { + len = min(miter.length, n_bytes - offset); + memset(miter.addr, val, len); + offset += len; + } +fini: + sg_miter_stop(&miter); + return offset; +} +EXPORT_SYMBOL(sgl_memset); +