diff options
Diffstat (limited to 'patches.tizen/0005-fs-buffer.c-Revoke-LRU-when-trying-to-drop-buffers.patch')
| -rw-r--r-- | patches.tizen/0005-fs-buffer.c-Revoke-LRU-when-trying-to-drop-buffers.patch | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/patches.tizen/0005-fs-buffer.c-Revoke-LRU-when-trying-to-drop-buffers.patch b/patches.tizen/0005-fs-buffer.c-Revoke-LRU-when-trying-to-drop-buffers.patch new file mode 100644 index 00000000000..41a0caf2c18 --- /dev/null +++ b/patches.tizen/0005-fs-buffer.c-Revoke-LRU-when-trying-to-drop-buffers.patch @@ -0,0 +1,95 @@ +From e2154558e6cea6a813e53e8b1c1f346d9b050d5b Mon Sep 17 00:00:00 2001 +From: Laura Abbott <lauraa@codeaurora.org> +Date: Wed, 12 Sep 2012 09:36:16 +0200 +Subject: [PATCH 0005/1302] fs/buffer.c: Revoke LRU when trying to drop buffers + +When a buffer is added to the LRU list, a reference is taken which is +not dropped until the buffer is evicted from the LRU list. This is the +correct behavior, however this LRU reference will prevent the buffer +from being dropped. This means that the buffer can't actually be dropped +until it is selected for eviction. There's no bound on the time spent +on the LRU list, which means that the buffer may be undroppable for +very long periods of time. Given that migration involves dropping +buffers, the associated page is now unmigratible for long periods of +time as well. CMA relies on being able to migrate a specific range +of pages, so these these types of failures make CMA significantly +less reliable, especially under high filesystem usage. + +Rather than waiting for the LRU algorithm to eventually kick out +the buffer, explicitly remove the buffer from the LRU list when trying +to drop it. There is still the possibility that the buffer +could be added back on the list, but that indicates the buffer is +still in use and would probably have other 'in use' indicates to +prevent dropping. + +Signed-off-by: Laura Abbott <lauraa@codeaurora.org> +Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com> +--- + fs/buffer.c | 38 ++++++++++++++++++++++++++++++++++++++ + 1 file changed, 38 insertions(+) + +diff --git a/fs/buffer.c b/fs/buffer.c +index d2a4d1b..087816b 100644 +--- a/fs/buffer.c ++++ b/fs/buffer.c +@@ -1413,12 +1413,49 @@ static bool has_bh_in_lru(int cpu, void *dummy) + return 0; + } + ++static void __evict_bh_lru(void *arg) ++{ ++ struct bh_lru *b = &get_cpu_var(bh_lrus); ++ struct buffer_head *bh = arg; ++ int i; ++ ++ for (i = 0; i < BH_LRU_SIZE; i++) { ++ if (b->bhs[i] == bh) { ++ brelse(b->bhs[i]); ++ b->bhs[i] = NULL; ++ goto out; ++ } ++ } ++out: ++ put_cpu_var(bh_lrus); ++} ++ ++static bool bh_exists_in_lru(int cpu, void *arg) ++{ ++ struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu); ++ struct buffer_head *bh = arg; ++ int i; ++ ++ for (i = 0; i < BH_LRU_SIZE; i++) { ++ if (b->bhs[i] == bh) ++ return 1; ++ } ++ ++ return 0; ++ ++} + void invalidate_bh_lrus(void) + { + on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1, GFP_KERNEL); + } + EXPORT_SYMBOL_GPL(invalidate_bh_lrus); + ++void evict_bh_lrus(struct buffer_head *bh) ++{ ++ on_each_cpu_cond(bh_exists_in_lru, __evict_bh_lru, bh, 1, GFP_ATOMIC); ++} ++EXPORT_SYMBOL_GPL(evict_bh_lrus); ++ + void set_bh_page(struct buffer_head *bh, + struct page *page, unsigned long offset) + { +@@ -3140,6 +3177,7 @@ drop_buffers(struct page *page, struct buffer_head **buffers_to_free) + + bh = head; + do { ++ evict_bh_lrus(bh); + if (buffer_write_io_error(bh) && page->mapping) + set_bit(AS_EIO, &page->mapping->flags); + if (buffer_busy(bh)) +-- +1.8.3.2 + |