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SG: Convert SCSI to use scatterlist helpers for sg chaining
Also change scsi_alloc_sgtable() to just return 0/failure, since it maps to the command passed in. ->request_buffer is now no longer needed, once drivers are adapted to use scsi_sglist() it can be killed. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Jens Axboe
parent
0db9299f48
commit
5ed7959ede
@ -739,138 +739,41 @@ static inline unsigned int scsi_sgtable_index(unsigned short nents)
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return index;
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}
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struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, gfp_t gfp_mask)
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static void scsi_sg_free(struct scatterlist *sgl, unsigned int nents)
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{
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struct scsi_host_sg_pool *sgp;
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struct scatterlist *sgl, *prev, *ret;
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unsigned int index;
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int this, left;
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sgp = scsi_sg_pools + scsi_sgtable_index(nents);
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mempool_free(sgl, sgp->pool);
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}
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static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask)
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{
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struct scsi_host_sg_pool *sgp;
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sgp = scsi_sg_pools + scsi_sgtable_index(nents);
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return mempool_alloc(sgp->pool, gfp_mask);
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}
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int scsi_alloc_sgtable(struct scsi_cmnd *cmd, gfp_t gfp_mask)
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{
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int ret;
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BUG_ON(!cmd->use_sg);
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left = cmd->use_sg;
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ret = prev = NULL;
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do {
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this = left;
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if (this > SCSI_MAX_SG_SEGMENTS) {
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this = SCSI_MAX_SG_SEGMENTS - 1;
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index = SG_MEMPOOL_NR - 1;
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} else
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index = scsi_sgtable_index(this);
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ret = __sg_alloc_table(&cmd->sg_table, cmd->use_sg, gfp_mask, scsi_sg_alloc);
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if (unlikely(ret))
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__sg_free_table(&cmd->sg_table, scsi_sg_free);
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left -= this;
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sgp = scsi_sg_pools + index;
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sgl = mempool_alloc(sgp->pool, gfp_mask);
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if (unlikely(!sgl))
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goto enomem;
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sg_init_table(sgl, sgp->size);
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/*
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* first loop through, set initial index and return value
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*/
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if (!ret)
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ret = sgl;
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/*
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* chain previous sglist, if any. we know the previous
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* sglist must be the biggest one, or we would not have
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* ended up doing another loop.
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*/
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if (prev)
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sg_chain(prev, SCSI_MAX_SG_SEGMENTS, sgl);
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/*
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* if we have nothing left, mark the last segment as
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* end-of-list
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*/
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if (!left)
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sg_mark_end(&sgl[this - 1]);
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/*
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* don't allow subsequent mempool allocs to sleep, it would
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* violate the mempool principle.
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*/
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gfp_mask &= ~__GFP_WAIT;
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gfp_mask |= __GFP_HIGH;
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prev = sgl;
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} while (left);
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/*
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* ->use_sg may get modified after dma mapping has potentially
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* shrunk the number of segments, so keep a copy of it for free.
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*/
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cmd->__use_sg = cmd->use_sg;
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cmd->request_buffer = cmd->sg_table.sgl;
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return ret;
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enomem:
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if (ret) {
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/*
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* Free entries chained off ret. Since we were trying to
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* allocate another sglist, we know that all entries are of
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* the max size.
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*/
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sgp = scsi_sg_pools + SG_MEMPOOL_NR - 1;
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prev = ret;
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ret = &ret[SCSI_MAX_SG_SEGMENTS - 1];
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while ((sgl = sg_chain_ptr(ret)) != NULL) {
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ret = &sgl[SCSI_MAX_SG_SEGMENTS - 1];
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mempool_free(sgl, sgp->pool);
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}
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mempool_free(prev, sgp->pool);
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}
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return NULL;
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}
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EXPORT_SYMBOL(scsi_alloc_sgtable);
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void scsi_free_sgtable(struct scsi_cmnd *cmd)
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{
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struct scatterlist *sgl = cmd->request_buffer;
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struct scsi_host_sg_pool *sgp;
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/*
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* if this is the biggest size sglist, check if we have
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* chained parts we need to free
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*/
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if (cmd->__use_sg > SCSI_MAX_SG_SEGMENTS) {
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unsigned short this, left;
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struct scatterlist *next;
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unsigned int index;
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left = cmd->__use_sg - (SCSI_MAX_SG_SEGMENTS - 1);
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next = sg_chain_ptr(&sgl[SCSI_MAX_SG_SEGMENTS - 1]);
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while (left && next) {
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sgl = next;
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this = left;
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if (this > SCSI_MAX_SG_SEGMENTS) {
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this = SCSI_MAX_SG_SEGMENTS - 1;
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index = SG_MEMPOOL_NR - 1;
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} else
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index = scsi_sgtable_index(this);
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left -= this;
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sgp = scsi_sg_pools + index;
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if (left)
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next = sg_chain_ptr(&sgl[sgp->size - 1]);
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mempool_free(sgl, sgp->pool);
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}
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/*
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* Restore original, will be freed below
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*/
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sgl = cmd->request_buffer;
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sgp = scsi_sg_pools + SG_MEMPOOL_NR - 1;
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} else
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sgp = scsi_sg_pools + scsi_sgtable_index(cmd->__use_sg);
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mempool_free(sgl, sgp->pool);
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__sg_free_table(&cmd->sg_table, scsi_sg_free);
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}
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EXPORT_SYMBOL(scsi_free_sgtable);
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@ -1120,8 +1023,7 @@ static int scsi_init_io(struct scsi_cmnd *cmd)
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/*
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* If sg table allocation fails, requeue request later.
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*/
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cmd->request_buffer = scsi_alloc_sgtable(cmd, GFP_ATOMIC);
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if (unlikely(!cmd->request_buffer)) {
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if (unlikely(scsi_alloc_sgtable(cmd, GFP_ATOMIC))) {
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scsi_unprep_request(req);
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return BLKPREP_DEFER;
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}
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@ -359,8 +359,7 @@ static int scsi_tgt_init_cmd(struct scsi_cmnd *cmd, gfp_t gfp_mask)
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int count;
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cmd->use_sg = rq->nr_phys_segments;
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cmd->request_buffer = scsi_alloc_sgtable(cmd, gfp_mask);
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if (!cmd->request_buffer)
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if (scsi_alloc_sgtable(cmd, gfp_mask))
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return -ENOMEM;
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cmd->request_bufflen = rq->data_len;
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@ -8,7 +8,6 @@
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#include <linux/scatterlist.h>
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struct request;
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struct scatterlist;
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struct Scsi_Host;
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struct scsi_device;
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@ -68,8 +67,8 @@ struct scsi_cmnd {
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void *request_buffer; /* Actual requested buffer */
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/* These elements define the operation we ultimately want to perform */
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struct sg_table sg_table;
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unsigned short use_sg; /* Number of pieces of scatter-gather */
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unsigned short __use_sg;
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unsigned underflow; /* Return error if less than
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this amount is transferred */
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@ -128,14 +127,14 @@ extern void *scsi_kmap_atomic_sg(struct scatterlist *sg, int sg_count,
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size_t *offset, size_t *len);
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extern void scsi_kunmap_atomic_sg(void *virt);
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extern struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *, gfp_t);
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extern int scsi_alloc_sgtable(struct scsi_cmnd *, gfp_t);
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extern void scsi_free_sgtable(struct scsi_cmnd *);
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extern int scsi_dma_map(struct scsi_cmnd *cmd);
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extern void scsi_dma_unmap(struct scsi_cmnd *cmd);
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#define scsi_sg_count(cmd) ((cmd)->use_sg)
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#define scsi_sglist(cmd) ((struct scatterlist *)(cmd)->request_buffer)
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#define scsi_sglist(cmd) ((cmd)->sg_table.sgl)
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#define scsi_bufflen(cmd) ((cmd)->request_bufflen)
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static inline void scsi_set_resid(struct scsi_cmnd *cmd, int resid)
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