diff options
| -rw-r--r-- | include/linux/scatterlist.h | 2 | ||||
| -rw-r--r-- | lib/scatterlist.c | 35 |
2 files changed, 37 insertions, 0 deletions
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index cb3c8fe6acd7..4b3286ac60c8 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -278,6 +278,8 @@ size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents, const void *buf, size_t buflen, off_t skip); size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, size_t buflen, off_t skip); +size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents, + size_t buflen, off_t skip); /* * Maximum number of entries that will be allocated in one piece, if diff --git a/lib/scatterlist.c b/lib/scatterlist.c index c6cf82242d65..be7b4dd6b68d 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -751,3 +751,38 @@ size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, return sg_copy_buffer(sgl, nents, buf, buflen, skip, true); } EXPORT_SYMBOL(sg_pcopy_to_buffer); + +/** + * sg_zero_buffer - Zero-out a part of a SG list + * @sgl: The SG list + * @nents: Number of SG entries + * @buflen: The number of bytes to zero out + * @skip: Number of bytes to skip before zeroing + * + * Returns the number of bytes zeroed. + **/ +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; +} +EXPORT_SYMBOL(sg_zero_buffer); |