diff options
| -rw-r--r-- | include/linux/scatterlist.h | 1 | ||||
| -rw-r--r-- | lib/scatterlist.c | 32 |
2 files changed, 33 insertions, 0 deletions
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index ed8f9e70df9b..a0edb992c9c3 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -221,6 +221,7 @@ static inline void *sg_virt(struct scatterlist *sg) } int sg_nents(struct scatterlist *sg); +int sg_nents_for_len(struct scatterlist *sg, u64 len); struct scatterlist *sg_next(struct scatterlist *); struct scatterlist *sg_last(struct scatterlist *s, unsigned int); void sg_init_table(struct scatterlist *, unsigned int); diff --git a/lib/scatterlist.c b/lib/scatterlist.c index c9f2e8c6ccc9..99fbc2f238c4 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -56,6 +56,38 @@ int sg_nents(struct scatterlist *sg) } EXPORT_SYMBOL(sg_nents); +/** + * sg_nents_for_len - return total count of entries in scatterlist + * needed to satisfy the supplied length + * @sg: The scatterlist + * @len: The total required length + * + * Description: + * Determines the number of entries in sg that are required to meet + * the supplied length, taking into acount chaining as well + * + * Returns: + * the number of sg entries needed, negative error on failure + * + **/ +int sg_nents_for_len(struct scatterlist *sg, u64 len) +{ + int nents; + u64 total; + + if (!len) + return 0; + + for (nents = 0, total = 0; sg; sg = sg_next(sg)) { + nents++; + total += sg->length; + if (total >= len) + return nents; + } + + return -EINVAL; +} +EXPORT_SYMBOL(sg_nents_for_len); /** * sg_last - return the last scatterlist entry in a list |