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author | Mikulas Patocka <mpatocka@redhat.com> | 2011-05-29 12:03:07 (GMT) |
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committer | Alasdair G Kergon <agk@redhat.com> | 2011-05-29 12:03:07 (GMT) |
commit | d04714580f12379fcf7a0f799e86c92b96dd4e1f (patch) | |
tree | 3a6c152dcb0d062dadfecd9fb8b1866a0fdbfce5 /drivers/md | |
parent | f99b55eec795bd0fd577ab3ca06f3acfbe3b1ab1 (diff) | |
download | linux-d04714580f12379fcf7a0f799e86c92b96dd4e1f.tar.xz |
dm kcopyd: alloc pages from the main page allocator
This patch changes dm-kcopyd so that it allocates pages from the main
page allocator with __GFP_NOWARN | __GFP_NORETRY flags (so that it can
fail in case of memory pressure). If the allocation fails, dm-kcopyd
allocates pages from its own reserve.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md')
-rw-r--r-- | drivers/md/dm-kcopyd.c | 91 |
1 files changed, 60 insertions, 31 deletions
diff --git a/drivers/md/dm-kcopyd.c b/drivers/md/dm-kcopyd.c index 0270844..5dfbdcb 100644 --- a/drivers/md/dm-kcopyd.c +++ b/drivers/md/dm-kcopyd.c @@ -37,8 +37,8 @@ *---------------------------------------------------------------*/ struct dm_kcopyd_client { struct page_list *pages; - unsigned int nr_pages; - unsigned int nr_free_pages; + unsigned nr_reserved_pages; + unsigned nr_free_pages; struct dm_io_client *io_client; @@ -70,6 +70,9 @@ static void wake(struct dm_kcopyd_client *kc) queue_work(kc->kcopyd_wq, &kc->kcopyd_work); } +/* + * Obtain one page for the use of kcopyd. + */ static struct page_list *alloc_pl(gfp_t gfp) { struct page_list *pl; @@ -93,34 +96,56 @@ static void free_pl(struct page_list *pl) kfree(pl); } -static int kcopyd_get_pages(struct dm_kcopyd_client *kc, - unsigned int nr, struct page_list **pages) +/* + * Add the provided pages to a client's free page list, releasing + * back to the system any beyond the reserved_pages limit. + */ +static void kcopyd_put_pages(struct dm_kcopyd_client *kc, struct page_list *pl) { - struct page_list *pl; - - if (kc->nr_free_pages < nr) - return -ENOMEM; + struct page_list *next; - kc->nr_free_pages -= nr; - for (*pages = pl = kc->pages; --nr; pl = pl->next) - ; + do { + next = pl->next; - kc->pages = pl->next; - pl->next = NULL; + if (kc->nr_free_pages >= kc->nr_reserved_pages) + free_pl(pl); + else { + pl->next = kc->pages; + kc->pages = pl; + kc->nr_free_pages++; + } - return 0; + pl = next; + } while (pl); } -static void kcopyd_put_pages(struct dm_kcopyd_client *kc, struct page_list *pl) +static int kcopyd_get_pages(struct dm_kcopyd_client *kc, + unsigned int nr, struct page_list **pages) { - struct page_list *cursor; + struct page_list *pl; - for (cursor = pl; cursor->next; cursor = cursor->next) - kc->nr_free_pages++; + *pages = NULL; + + do { + pl = alloc_pl(__GFP_NOWARN | __GFP_NORETRY); + if (unlikely(!pl)) { + /* Use reserved pages */ + pl = kc->pages; + if (unlikely(!pl)) + goto out_of_memory; + kc->pages = pl->next; + kc->nr_free_pages--; + } + pl->next = *pages; + *pages = pl; + } while (--nr); + + return 0; - kc->nr_free_pages++; - cursor->next = kc->pages; - kc->pages = pl; +out_of_memory: + if (*pages) + kcopyd_put_pages(kc, *pages); + return -ENOMEM; } /* @@ -137,12 +162,15 @@ static void drop_pages(struct page_list *pl) } } -static int client_alloc_pages(struct dm_kcopyd_client *kc, unsigned int nr) +/* + * Allocate and reserve nr_pages for the use of a specific client. + */ +static int client_reserve_pages(struct dm_kcopyd_client *kc, unsigned nr_pages) { - unsigned int i; + unsigned i; struct page_list *pl = NULL, *next; - for (i = 0; i < nr; i++) { + for (i = 0; i < nr_pages; i++) { next = alloc_pl(GFP_KERNEL); if (!next) { if (pl) @@ -153,17 +181,18 @@ static int client_alloc_pages(struct dm_kcopyd_client *kc, unsigned int nr) pl = next; } + kc->nr_reserved_pages += nr_pages; kcopyd_put_pages(kc, pl); - kc->nr_pages += nr; + return 0; } static void client_free_pages(struct dm_kcopyd_client *kc) { - BUG_ON(kc->nr_free_pages != kc->nr_pages); + BUG_ON(kc->nr_free_pages != kc->nr_reserved_pages); drop_pages(kc->pages); kc->pages = NULL; - kc->nr_free_pages = kc->nr_pages = 0; + kc->nr_free_pages = kc->nr_reserved_pages = 0; } /*----------------------------------------------------------------- @@ -607,7 +636,7 @@ int kcopyd_cancel(struct kcopyd_job *job, int block) /*----------------------------------------------------------------- * Client setup *---------------------------------------------------------------*/ -int dm_kcopyd_client_create(unsigned int nr_pages, +int dm_kcopyd_client_create(unsigned min_pages, struct dm_kcopyd_client **result) { int r = -ENOMEM; @@ -633,12 +662,12 @@ int dm_kcopyd_client_create(unsigned int nr_pages, goto bad_workqueue; kc->pages = NULL; - kc->nr_pages = kc->nr_free_pages = 0; - r = client_alloc_pages(kc, nr_pages); + kc->nr_reserved_pages = kc->nr_free_pages = 0; + r = client_reserve_pages(kc, min_pages); if (r) goto bad_client_pages; - kc->io_client = dm_io_client_create(nr_pages); + kc->io_client = dm_io_client_create(min_pages); if (IS_ERR(kc->io_client)) { r = PTR_ERR(kc->io_client); goto bad_io_client; |