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author | NeilBrown <neilb@suse.de> | 2022-05-10 03:20:49 +0200 |
---|---|---|
committer | akpm <akpm@linux-foundation.org> | 2022-05-10 03:20:49 +0200 |
commit | 5169b844b7dd5934cd4f22ab66de0cc669abf0b0 (patch) | |
tree | 97adf12221bb1191c14dafc9aae6713586060a55 /mm/page_io.c | |
parent | doc: update documentation for swap_activate and swap_rw (diff) | |
download | linux-5169b844b7dd5934cd4f22ab66de0cc669abf0b0.tar.xz linux-5169b844b7dd5934cd4f22ab66de0cc669abf0b0.zip |
mm: submit multipage reads for SWP_FS_OPS swap-space
swap_readpage() is given one page at a time, but may be called repeatedly
in succession.
For block-device swap-space, the blk_plug functionality allows the
multiple pages to be combined together at lower layers. That cannot be
used for SWP_FS_OPS as blk_plug may not exist - it is only active when
CONFIG_BLOCK=y. Consequently all swap reads over NFS are single page
reads.
With this patch we pass in a pointer-to-pointer when swap_readpage can
store state between calls - much like the effect of blk_plug. After
calling swap_readpage() some number of times, the state will be passed to
swap_read_unplug() which can submit the combined request.
Link: https://lkml.kernel.org/r/164859778127.29473.14059420492644907783.stgit@noble.brown
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: David Howells <dhowells@redhat.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/page_io.c')
-rw-r--r-- | mm/page_io.c | 104 |
1 files changed, 69 insertions, 35 deletions
diff --git a/mm/page_io.c b/mm/page_io.c index fafbda338f72..a63510fd6611 100644 --- a/mm/page_io.c +++ b/mm/page_io.c @@ -237,7 +237,8 @@ static void bio_associate_blkg_from_page(struct bio *bio, struct page *page) struct swap_iocb { struct kiocb iocb; - struct bio_vec bvec; + struct bio_vec bvec[SWAP_CLUSTER_MAX]; + int pages; }; static mempool_t *sio_pool; @@ -257,7 +258,7 @@ int sio_pool_init(void) static void sio_write_complete(struct kiocb *iocb, long ret) { struct swap_iocb *sio = container_of(iocb, struct swap_iocb, iocb); - struct page *page = sio->bvec.bv_page; + struct page *page = sio->bvec[0].bv_page; if (ret != PAGE_SIZE) { /* @@ -295,10 +296,10 @@ static int swap_writepage_fs(struct page *page, struct writeback_control *wbc) init_sync_kiocb(&sio->iocb, swap_file); sio->iocb.ki_complete = sio_write_complete; sio->iocb.ki_pos = page_file_offset(page); - sio->bvec.bv_page = page; - sio->bvec.bv_len = PAGE_SIZE; - sio->bvec.bv_offset = 0; - iov_iter_bvec(&from, WRITE, &sio->bvec, 1, PAGE_SIZE); + sio->bvec[0].bv_page = page; + sio->bvec[0].bv_len = PAGE_SIZE; + sio->bvec[0].bv_offset = 0; + iov_iter_bvec(&from, WRITE, &sio->bvec[0], 1, PAGE_SIZE); ret = mapping->a_ops->swap_rw(&sio->iocb, &from); if (ret != -EIOCBQUEUED) sio_write_complete(&sio->iocb, ret); @@ -346,46 +347,66 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc, static void sio_read_complete(struct kiocb *iocb, long ret) { struct swap_iocb *sio = container_of(iocb, struct swap_iocb, iocb); - struct page *page = sio->bvec.bv_page; + int p; - if (ret != 0 && ret != PAGE_SIZE) { - SetPageError(page); - ClearPageUptodate(page); - pr_alert_ratelimited("Read-error on swap-device\n"); + if (ret == PAGE_SIZE * sio->pages) { + for (p = 0; p < sio->pages; p++) { + struct page *page = sio->bvec[p].bv_page; + + SetPageUptodate(page); + unlock_page(page); + } + count_vm_events(PSWPIN, sio->pages); } else { - SetPageUptodate(page); - count_vm_event(PSWPIN); + for (p = 0; p < sio->pages; p++) { + struct page *page = sio->bvec[p].bv_page; + + SetPageError(page); + ClearPageUptodate(page); + unlock_page(page); + } + pr_alert_ratelimited("Read-error on swap-device\n"); } - unlock_page(page); mempool_free(sio, sio_pool); } -static int swap_readpage_fs(struct page *page) +static void swap_readpage_fs(struct page *page, + struct swap_iocb **plug) { struct swap_info_struct *sis = page_swap_info(page); - struct file *swap_file = sis->swap_file; - struct address_space *mapping = swap_file->f_mapping; - struct iov_iter from; - struct swap_iocb *sio; + struct swap_iocb *sio = NULL; loff_t pos = page_file_offset(page); - int ret; - - sio = mempool_alloc(sio_pool, GFP_KERNEL); - init_sync_kiocb(&sio->iocb, swap_file); - sio->iocb.ki_pos = pos; - sio->iocb.ki_complete = sio_read_complete; - sio->bvec.bv_page = page; - sio->bvec.bv_len = PAGE_SIZE; - sio->bvec.bv_offset = 0; - iov_iter_bvec(&from, READ, &sio->bvec, 1, PAGE_SIZE); - ret = mapping->a_ops->swap_rw(&sio->iocb, &from); - if (ret != -EIOCBQUEUED) - sio_read_complete(&sio->iocb, ret); - return ret; + if (plug) + sio = *plug; + if (sio) { + if (sio->iocb.ki_filp != sis->swap_file || + sio->iocb.ki_pos + sio->pages * PAGE_SIZE != pos) { + swap_read_unplug(sio); + sio = NULL; + } + } + if (!sio) { + sio = mempool_alloc(sio_pool, GFP_KERNEL); + init_sync_kiocb(&sio->iocb, sis->swap_file); + sio->iocb.ki_pos = pos; + sio->iocb.ki_complete = sio_read_complete; + sio->pages = 0; + } + sio->bvec[sio->pages].bv_page = page; + sio->bvec[sio->pages].bv_len = PAGE_SIZE; + sio->bvec[sio->pages].bv_offset = 0; + sio->pages += 1; + if (sio->pages == ARRAY_SIZE(sio->bvec) || !plug) { + swap_read_unplug(sio); + sio = NULL; + } + if (plug) + *plug = sio; } -int swap_readpage(struct page *page, bool synchronous) +int swap_readpage(struct page *page, bool synchronous, + struct swap_iocb **plug) { struct bio *bio; int ret = 0; @@ -413,7 +434,7 @@ int swap_readpage(struct page *page, bool synchronous) } if (data_race(sis->flags & SWP_FS_OPS)) { - ret = swap_readpage_fs(page); + swap_readpage_fs(page, plug); goto out; } @@ -459,3 +480,16 @@ out: delayacct_swapin_end(); return ret; } + +void __swap_read_unplug(struct swap_iocb *sio) +{ + struct iov_iter from; + struct address_space *mapping = sio->iocb.ki_filp->f_mapping; + int ret; + + iov_iter_bvec(&from, READ, sio->bvec, sio->pages, + PAGE_SIZE * sio->pages); + ret = mapping->a_ops->swap_rw(&sio->iocb, &from); + if (ret != -EIOCBQUEUED) + sio_read_complete(&sio->iocb, ret); +} |