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author | Christoph Hellwig <hch@lst.de> | 2014-04-15 14:38:31 +0200 |
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committer | Christoph Hellwig <hch@lst.de> | 2014-07-25 17:16:21 -0400 |
commit | c53c6d6a68b13b1dff2892551b56cfdc07887d9e (patch) | |
tree | 8bd6ddc1ff0f33e357ad6c230f62fd7b1cf1b28a /lib | |
parent | f6d47e74fcb2814225e429c94355ad1c551daffb (diff) | |
download | linux-stable-c53c6d6a68b13b1dff2892551b56cfdc07887d9e.tar.gz linux-stable-c53c6d6a68b13b1dff2892551b56cfdc07887d9e.tar.bz2 linux-stable-c53c6d6a68b13b1dff2892551b56cfdc07887d9e.zip |
scatterlist: allow chaining to preallocated chunks
Blk-mq drivers usually preallocate their S/G list as part of the request,
but if we want to support the very large S/G lists currently supported by
the SCSI code that would tie up a lot of memory in the preallocated request
pool. Add support to the scatterlist code so that it can initialize a
S/G list that uses a preallocated first chunks and dynamically allocated
additional chunks. That way the scsi-mq code can preallocate a first
page worth of S/G entries as part of the request, and dynamically extend
the S/G list when needed.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Webb Scales <webbnh@hp.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Tested-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Robert Elliott <elliott@hp.com>
Diffstat (limited to 'lib')
-rw-r--r-- | lib/scatterlist.c | 25 |
1 files changed, 17 insertions, 8 deletions
diff --git a/lib/scatterlist.c b/lib/scatterlist.c index 3a8e8e8fb2a5..b4415fceb7e7 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -165,6 +165,7 @@ static void sg_kfree(struct scatterlist *sg, unsigned int nents) * __sg_free_table - Free a previously mapped sg table * @table: The sg table header to use * @max_ents: The maximum number of entries per single scatterlist + * @skip_first_chunk: don't free the (preallocated) first scatterlist chunk * @free_fn: Free function * * Description: @@ -174,7 +175,7 @@ static void sg_kfree(struct scatterlist *sg, unsigned int nents) * **/ void __sg_free_table(struct sg_table *table, unsigned int max_ents, - sg_free_fn *free_fn) + bool skip_first_chunk, sg_free_fn *free_fn) { struct scatterlist *sgl, *next; @@ -202,7 +203,10 @@ void __sg_free_table(struct sg_table *table, unsigned int max_ents, } table->orig_nents -= sg_size; - free_fn(sgl, alloc_size); + if (!skip_first_chunk) { + free_fn(sgl, alloc_size); + skip_first_chunk = false; + } sgl = next; } @@ -217,7 +221,7 @@ EXPORT_SYMBOL(__sg_free_table); **/ void sg_free_table(struct sg_table *table) { - __sg_free_table(table, SG_MAX_SINGLE_ALLOC, sg_kfree); + __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree); } EXPORT_SYMBOL(sg_free_table); @@ -241,8 +245,8 @@ EXPORT_SYMBOL(sg_free_table); * **/ int __sg_alloc_table(struct sg_table *table, unsigned int nents, - unsigned int max_ents, gfp_t gfp_mask, - sg_alloc_fn *alloc_fn) + unsigned int max_ents, struct scatterlist *first_chunk, + gfp_t gfp_mask, sg_alloc_fn *alloc_fn) { struct scatterlist *sg, *prv; unsigned int left; @@ -269,7 +273,12 @@ int __sg_alloc_table(struct sg_table *table, unsigned int nents, left -= sg_size; - sg = alloc_fn(alloc_size, gfp_mask); + if (first_chunk) { + sg = first_chunk; + first_chunk = NULL; + } else { + sg = alloc_fn(alloc_size, gfp_mask); + } if (unlikely(!sg)) { /* * Adjust entry count to reflect that the last @@ -324,9 +333,9 @@ int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask) int ret; ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC, - gfp_mask, sg_kmalloc); + NULL, gfp_mask, sg_kmalloc); if (unlikely(ret)) - __sg_free_table(table, SG_MAX_SINGLE_ALLOC, sg_kfree); + __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree); return ret; } |