/*
* Start background writeback (via pdflush) at this percentage
*/
-int dirty_background_ratio = 10;
+int dirty_background_ratio = 5;
/*
* The generator of dirty data starts writeback at this percentage
*/
-int vm_dirty_ratio = 40;
+int vm_dirty_ratio = 10;
/*
* The interval between `kupdate'-style writebacks, in jiffies
* We make sure that the background writeout level is below the adjusted
* clamping level.
*/
+
+static unsigned long highmem_dirtyable_memory(unsigned long total)
+{
+#ifdef CONFIG_HIGHMEM
+ int node;
+ unsigned long x = 0;
+
+ for_each_online_node(node) {
+ struct zone *z =
+ &NODE_DATA(node)->node_zones[ZONE_HIGHMEM];
+
+ x += zone_page_state(z, NR_FREE_PAGES)
+ + zone_page_state(z, NR_INACTIVE)
+ + zone_page_state(z, NR_ACTIVE);
+ }
+ /*
+ * Make sure that the number of highmem pages is never larger
+ * than the number of the total dirtyable memory. This can only
+ * occur in very strange VM situations but we want to make sure
+ * that this does not occur.
+ */
+ return min(x, total);
+#else
+ return 0;
+#endif
+}
+
+static unsigned long determine_dirtyable_memory(void)
+{
+ unsigned long x;
+
+ x = global_page_state(NR_FREE_PAGES)
+ + global_page_state(NR_INACTIVE)
+ + global_page_state(NR_ACTIVE);
+ x -= highmem_dirtyable_memory(x);
+ return x + 1; /* Ensure that we never return 0 */
+}
+
static void
get_dirty_limits(long *pbackground, long *pdirty,
struct address_space *mapping)
int unmapped_ratio;
long background;
long dirty;
- unsigned long available_memory = vm_total_pages;
+ unsigned long available_memory = determine_dirtyable_memory();
struct task_struct *tsk;
-#ifdef CONFIG_HIGHMEM
- /*
- * If this mapping can only allocate from low memory,
- * we exclude high memory from our count.
- */
- if (mapping && !(mapping_gfp_mask(mapping) & __GFP_HIGHMEM))
- available_memory -= totalhigh_pages;
-#endif
-
-
unmapped_ratio = 100 - ((global_page_state(NR_FILE_MAPPED) +
global_page_state(NR_ANON_PAGES)) * 100) /
- vm_total_pages;
+ available_memory;
dirty_ratio = vm_dirty_ratio;
if (dirty_ratio > unmapped_ratio / 2)
}
EXPORT_SYMBOL(balance_dirty_pages_ratelimited_nr);
-void throttle_vm_writeout(void)
+void throttle_vm_writeout(gfp_t gfp_mask)
{
long background_thresh;
long dirty_thresh;
+ if ((gfp_mask & (__GFP_FS|__GFP_IO)) != (__GFP_FS|__GFP_IO)) {
+ /*
+ * The caller might hold locks which can prevent IO completion
+ * or progress in the filesystem. So we cannot just sit here
+ * waiting for IO to complete.
+ */
+ congestion_wait(WRITE, HZ/10);
+ return;
+ }
+
for ( ; ; ) {
get_dirty_limits(&background_thresh, &dirty_thresh, NULL);
}
}
-
/*
* writeback at least _min_pages, and keep writing until the amount of dirty
* memory is less than the background threshold, or until we're all clean.
* sysctl handler for /proc/sys/vm/dirty_writeback_centisecs
*/
int dirty_writeback_centisecs_handler(ctl_table *table, int write,
- struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
+ struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
{
proc_dointvec_userhz_jiffies(table, write, file, buffer, length, ppos);
- if (dirty_writeback_interval) {
- mod_timer(&wb_timer,
- jiffies + dirty_writeback_interval);
- } else {
+ if (dirty_writeback_interval)
+ mod_timer(&wb_timer, jiffies + dirty_writeback_interval);
+ else
del_timer(&wb_timer);
- }
return 0;
}
ratelimit_handler(struct notifier_block *self, unsigned long u, void *v)
{
writeback_set_ratelimit();
- return 0;
+ return NOTIFY_DONE;
}
static struct notifier_block __cpuinitdata ratelimit_nb = {
};
/*
- * If the machine has a large highmem:lowmem ratio then scale back the default
- * dirty memory thresholds: allowing too much dirty highmem pins an excessive
- * number of buffer_heads.
+ * Called early on to tune the page writeback dirty limits.
+ *
+ * We used to scale dirty pages according to how total memory
+ * related to pages that could be allocated for buffers (by
+ * comparing nr_free_buffer_pages() to vm_total_pages.
+ *
+ * However, that was when we used "dirty_ratio" to scale with
+ * all memory, and we don't do that any more. "dirty_ratio"
+ * is now applied to total non-HIGHPAGE memory (by subtracting
+ * totalhigh_pages from vm_total_pages), and as such we can't
+ * get into the old insane situation any more where we had
+ * large amounts of dirty pages compared to a small amount of
+ * non-HIGHMEM memory.
+ *
+ * But we might still want to scale the dirty_ratio by how
+ * much memory the box has..
*/
void __init page_writeback_init(void)
{
- long buffer_pages = nr_free_buffer_pages();
- long correction;
-
- correction = (100 * 4 * buffer_pages) / vm_total_pages;
-
- if (correction < 100) {
- dirty_background_ratio *= correction;
- dirty_background_ratio /= 100;
- vm_dirty_ratio *= correction;
- vm_dirty_ratio /= 100;
-
- if (dirty_background_ratio <= 0)
- dirty_background_ratio = 1;
- if (vm_dirty_ratio <= 0)
- vm_dirty_ratio = 1;
- }
mod_timer(&wb_timer, jiffies + dirty_writeback_interval);
writeback_set_ratelimit();
register_cpu_notifier(&ratelimit_nb);
}
/**
- * generic_writepages - walk the list of dirty pages of the given
- * address space and writepage() all of them.
- *
+ * write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
* @mapping: address space structure to write
* @wbc: subtract the number of written pages from *@wbc->nr_to_write
+ * @writepage: function called for each page
+ * @data: data passed to writepage function
*
- * This is a library function, which implements the writepages()
- * address_space_operation.
- *
- * If a page is already under I/O, generic_writepages() skips it, even
+ * If a page is already under I/O, write_cache_pages() skips it, even
* if it's dirty. This is desirable behaviour for memory-cleaning writeback,
* but it is INCORRECT for data-integrity system calls such as fsync(). fsync()
* and msync() need to guarantee that all the data which was dirty at the time
* the call was made get new I/O started against them. If wbc->sync_mode is
* WB_SYNC_ALL then we were called for data integrity and we must wait for
* existing IO to complete.
- *
- * Derived from mpage_writepages() - if you fix this you should check that
- * also!
*/
-int generic_writepages(struct address_space *mapping,
- struct writeback_control *wbc)
+int write_cache_pages(struct address_space *mapping,
+ struct writeback_control *wbc, writepage_t writepage,
+ void *data)
{
struct backing_dev_info *bdi = mapping->backing_dev_info;
int ret = 0;
int done = 0;
- int (*writepage)(struct page *page, struct writeback_control *wbc);
struct pagevec pvec;
int nr_pages;
pgoff_t index;
return 0;
}
- writepage = mapping->a_ops->writepage;
-
- /* deal with chardevs and other special file */
- if (!writepage)
- return 0;
-
pagevec_init(&pvec, 0);
if (wbc->range_cyclic) {
index = mapping->writeback_index; /* Start from prev offset */
continue;
}
- ret = (*writepage)(page, wbc);
- if (ret) {
- if (ret == -ENOSPC)
- set_bit(AS_ENOSPC, &mapping->flags);
- else
- set_bit(AS_EIO, &mapping->flags);
- }
+ ret = (*writepage)(page, wbc, data);
if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE))
unlock_page(page);
mapping->writeback_index = index;
return ret;
}
+EXPORT_SYMBOL(write_cache_pages);
+
+/*
+ * Function used by generic_writepages to call the real writepage
+ * function and set the mapping flags on error
+ */
+static int __writepage(struct page *page, struct writeback_control *wbc,
+ void *data)
+{
+ struct address_space *mapping = data;
+ int ret = mapping->a_ops->writepage(page, wbc);
+ mapping_set_error(mapping, ret);
+ return ret;
+}
+
+/**
+ * generic_writepages - walk the list of dirty pages of the given address space and writepage() all of them.
+ * @mapping: address space structure to write
+ * @wbc: subtract the number of written pages from *@wbc->nr_to_write
+ *
+ * This is a library function, which implements the writepages()
+ * address_space_operation.
+ */
+int generic_writepages(struct address_space *mapping,
+ struct writeback_control *wbc)
+{
+ /* deal with chardevs and other special file */
+ if (!mapping->a_ops->writepage)
+ return 0;
+
+ return write_cache_pages(mapping, wbc, __writepage, mapping);
+}
EXPORT_SYMBOL(generic_writepages);
/**
* write_one_page - write out a single page and optionally wait on I/O
- *
* @page: the page to write
* @wait: if true, wait on writeout
*
EXPORT_SYMBOL(write_one_page);
/*
+ * For address_spaces which do not use buffers nor write back.
+ */
+int __set_page_dirty_no_writeback(struct page *page)
+{
+ if (!PageDirty(page))
+ SetPageDirty(page);
+ return 0;
+}
+
+/*
* For address_spaces which do not use buffers. Just tag the page as dirty in
* its radix tree.
*
mapping2 = page_mapping(page);
if (mapping2) { /* Race with truncate? */
BUG_ON(mapping2 != mapping);
+ WARN_ON_ONCE(!PagePrivate(page) && !PageUptodate(page));
if (mapping_cap_account_dirty(mapping)) {
__inc_zone_page_state(page, NR_FILE_DIRTY);
task_io_account_write(PAGE_CACHE_SIZE);
EXPORT_SYMBOL(set_page_dirty_lock);
/*
- * Clear a page's dirty flag, while caring for dirty memory accounting.
- * Returns true if the page was previously dirty.
- */
-int test_clear_page_dirty(struct page *page)
-{
- struct address_space *mapping = page_mapping(page);
- unsigned long flags;
-
- if (!mapping)
- return TestClearPageDirty(page);
-
- write_lock_irqsave(&mapping->tree_lock, flags);
- if (TestClearPageDirty(page)) {
- radix_tree_tag_clear(&mapping->page_tree,
- page_index(page), PAGECACHE_TAG_DIRTY);
- write_unlock_irqrestore(&mapping->tree_lock, flags);
- /*
- * We can continue to use `mapping' here because the
- * page is locked, which pins the address_space
- */
- if (mapping_cap_account_dirty(mapping)) {
- page_mkclean(page);
- dec_zone_page_state(page, NR_FILE_DIRTY);
- }
- return 1;
- }
- write_unlock_irqrestore(&mapping->tree_lock, flags);
- return 0;
-}
-EXPORT_SYMBOL(test_clear_page_dirty);
-
-/*
* Clear a page's dirty flag, while caring for dirty memory accounting.
* Returns true if the page was previously dirty.
*
{
struct address_space *mapping = page_mapping(page);
- if (!mapping)
- return TestClearPageDirty(page);
+ BUG_ON(!PageLocked(page));
- if (TestClearPageDirty(page)) {
- if (mapping_cap_account_dirty(mapping)) {
- page_mkclean(page);
+ ClearPageReclaim(page);
+ if (mapping && mapping_cap_account_dirty(mapping)) {
+ /*
+ * Yes, Virginia, this is indeed insane.
+ *
+ * We use this sequence to make sure that
+ * (a) we account for dirty stats properly
+ * (b) we tell the low-level filesystem to
+ * mark the whole page dirty if it was
+ * dirty in a pagetable. Only to then
+ * (c) clean the page again and return 1 to
+ * cause the writeback.
+ *
+ * This way we avoid all nasty races with the
+ * dirty bit in multiple places and clearing
+ * them concurrently from different threads.
+ *
+ * Note! Normally the "set_page_dirty(page)"
+ * has no effect on the actual dirty bit - since
+ * that will already usually be set. But we
+ * need the side effects, and it can help us
+ * avoid races.
+ *
+ * We basically use the page "master dirty bit"
+ * as a serialization point for all the different
+ * threads doing their things.
+ */
+ if (page_mkclean(page))
+ set_page_dirty(page);
+ /*
+ * We carefully synchronise fault handlers against
+ * installing a dirty pte and marking the page dirty
+ * at this point. We do this by having them hold the
+ * page lock at some point after installing their
+ * pte, but before marking the page dirty.
+ * Pages are always locked coming in here, so we get
+ * the desired exclusion. See mm/memory.c:do_wp_page()
+ * for more comments.
+ */
+ if (TestClearPageDirty(page)) {
dec_zone_page_state(page, NR_FILE_DIRTY);
+ return 1;
}
- return 1;
+ return 0;
}
- return 0;
+ return TestClearPageDirty(page);
}
EXPORT_SYMBOL(clear_page_dirty_for_io);
} else {
ret = TestClearPageWriteback(page);
}
+ if (ret)
+ dec_zone_page_state(page, NR_WRITEBACK);
return ret;
}
} else {
ret = TestSetPageWriteback(page);
}
+ if (!ret)
+ inc_zone_page_state(page, NR_WRITEBACK);
return ret;
}
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff