From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx168.postini.com [74.125.245.168]) by kanga.kvack.org (Postfix) with SMTP id 06A276B007E for ; Wed, 14 Mar 2012 13:14:36 -0400 (EDT) From: Andor Daam Subject: [PATCH 1/2] frontswap: allow backends to register after frontswap initilization Date: Wed, 14 Mar 2012 18:13:27 +0100 Message-Id: <1331745208-1010-2-git-send-email-andor.daam@googlemail.com> In-Reply-To: <1331745208-1010-1-git-send-email-andor.daam@googlemail.com> References: <1331745208-1010-1-git-send-email-andor.daam@googlemail.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: dan.magenheimer@oracle.com, sjenning@linux.vnet.ibm.com, ilendir@googlemail.com, konrad.wilk@oracle.com, fschmaus@gmail.com, i4passt@lists.informatik.uni-erlangen.de, ngupta@vflare.org, Andor Daam This patch allows backends to register to frontswap even after swapon was run. Before a backend registers all calls to init are recorded and the creation of tmem_pools delayed until a backend registers. Sigend-off-by: Stefan Hengelein Signed-off-by: Florian Schmaus Sigend-off-by: Andor Daam --- mm/frontswap.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++------- 1 files changed, 63 insertions(+), 9 deletions(-) diff --git a/mm/frontswap.c b/mm/frontswap.c index 2b80c5a..209487b 100644 --- a/mm/frontswap.c +++ b/mm/frontswap.c @@ -49,15 +49,33 @@ static u64 frontswap_failed_puts; static u64 frontswap_invalidates; /* + * When no backend is registered all calls to init are registered and + * remembered but fail to create tmem_pools. When a backend registers with + * frontswap the previous calls to init are executed to create tmem_pools + * and set the respective poolids. + * While no backend is registered all "puts", "gets" and "flushes" are + * ignored or fail. + */ +#define MAX_INITIALIZABLE_SD 32 +static int sds[MAX_INITIALIZABLE_SD]; +static int backend_registered; + +/* * Register operations for frontswap, returning previous thus allowing * detection of multiple backends and possible nesting */ struct frontswap_ops frontswap_register_ops(struct frontswap_ops *ops) { struct frontswap_ops old = frontswap_ops; + int i; frontswap_ops = *ops; - frontswap_enabled = 1; + + backend_registered = 1; + for (i = 0; i < MAX_INITIALIZABLE_SD; i++) { + if (sds[i] != -1) + (*frontswap_ops.init)(sds[i]); + } return old; } EXPORT_SYMBOL(frontswap_register_ops); @@ -66,12 +84,21 @@ EXPORT_SYMBOL(frontswap_register_ops); void __frontswap_init(unsigned type) { struct swap_info_struct *sis = swap_info[type]; + int i; BUG_ON(sis == NULL); if (sis->frontswap_map == NULL) return; - if (frontswap_enabled) - (*frontswap_ops.init)(type); + if (frontswap_enabled) { + if (backend_registered) + (*frontswap_ops.init)(type); + for (i = 0; i < MAX_INITIALIZABLE_SD; i++) { + if (sds[i] == -1) { + sds[i] = type; + break; + } + } + } } EXPORT_SYMBOL(__frontswap_init); @@ -90,6 +117,11 @@ int __frontswap_put_page(struct page *page) struct swap_info_struct *sis = swap_info[type]; pgoff_t offset = swp_offset(entry); + if (!backend_registered) { + frontswap_failed_puts++; + return ret; + } + BUG_ON(!PageLocked(page)); BUG_ON(sis == NULL); if (frontswap_test(sis, offset)) @@ -127,12 +159,16 @@ int __frontswap_get_page(struct page *page) struct swap_info_struct *sis = swap_info[type]; pgoff_t offset = swp_offset(entry); + if (!backend_registered) + return ret; + BUG_ON(!PageLocked(page)); BUG_ON(sis == NULL); if (frontswap_test(sis, offset)) ret = (*frontswap_ops.get_page)(type, offset, page); if (ret == 0) frontswap_gets++; + return ret; } EXPORT_SYMBOL(__frontswap_get_page); @@ -145,6 +181,9 @@ void __frontswap_invalidate_page(unsigned type, pgoff_t offset) { struct swap_info_struct *sis = swap_info[type]; + if (!backend_registered) + return; + BUG_ON(sis == NULL); if (frontswap_test(sis, offset)) { (*frontswap_ops.invalidate_page)(type, offset); @@ -162,13 +201,23 @@ EXPORT_SYMBOL(__frontswap_invalidate_page); void __frontswap_invalidate_area(unsigned type) { struct swap_info_struct *sis = swap_info[type]; + int i; - BUG_ON(sis == NULL); - if (sis->frontswap_map == NULL) - return; - (*frontswap_ops.invalidate_area)(type); - atomic_set(&sis->frontswap_pages, 0); - memset(sis->frontswap_map, 0, sis->max / sizeof(long)); + if (backend_registered) { + BUG_ON(sis == NULL); + if (sis->frontswap_map == NULL) + return; + (*frontswap_ops.invalidate_area)(type); + atomic_set(&sis->frontswap_pages, 0); + memset(sis->frontswap_map, 0, sis->max / sizeof(long)); + } else { + for (i = 0; i < MAX_INITIALIZABLE_SD; i++) { + if (sds[i] == type) { + sds[i] = -1; + break; + } + } + } } EXPORT_SYMBOL(__frontswap_invalidate_area); @@ -255,6 +304,7 @@ EXPORT_SYMBOL(frontswap_curr_pages); static int __init init_frontswap(void) { int err = 0; + int i; #ifdef CONFIG_DEBUG_FS struct dentry *root = debugfs_create_dir("frontswap", NULL); @@ -267,6 +317,10 @@ static int __init init_frontswap(void) debugfs_create_u64("invalidates", S_IRUGO, root, &frontswap_invalidates); #endif + for (i = 0; i < MAX_INITIALIZABLE_SD; i++) + sds[i] = -1; + + frontswap_enabled = 1; return err; } -- 1.7.5.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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