Fix race in create_empty_buffers() vs __set_page_dirty_buffers()
Nick Piggin noticed this (very unlikely) race between setting a page dirty and creating the buffers for it - we need to hold the mapping private_lock until we've set the page dirty bit in order to make sure that create_empty_buffers() might not build up a set of buffers without the dirty bits set when the page is dirty. I doubt anybody has ever hit this race (and it didn't solve the issue Nick was looking at), but as Nick says: "Still, it does appear to solve a real race, which we should close." Acked-by: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Родитель
68df3755e3
Коммит
a8e7d49aa7
23
fs/buffer.c
23
fs/buffer.c
|
@ -760,15 +760,9 @@ EXPORT_SYMBOL(mark_buffer_dirty_inode);
|
|||
* If warn is true, then emit a warning if the page is not uptodate and has
|
||||
* not been truncated.
|
||||
*/
|
||||
static int __set_page_dirty(struct page *page,
|
||||
static void __set_page_dirty(struct page *page,
|
||||
struct address_space *mapping, int warn)
|
||||
{
|
||||
if (unlikely(!mapping))
|
||||
return !TestSetPageDirty(page);
|
||||
|
||||
if (TestSetPageDirty(page))
|
||||
return 0;
|
||||
|
||||
spin_lock_irq(&mapping->tree_lock);
|
||||
if (page->mapping) { /* Race with truncate? */
|
||||
WARN_ON_ONCE(warn && !PageUptodate(page));
|
||||
|
@ -785,8 +779,6 @@ static int __set_page_dirty(struct page *page,
|
|||
}
|
||||
spin_unlock_irq(&mapping->tree_lock);
|
||||
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
|
||||
|
||||
return 1;
|
||||
}
|
||||
|
||||
/*
|
||||
|
@ -816,6 +808,7 @@ static int __set_page_dirty(struct page *page,
|
|||
*/
|
||||
int __set_page_dirty_buffers(struct page *page)
|
||||
{
|
||||
int newly_dirty;
|
||||
struct address_space *mapping = page_mapping(page);
|
||||
|
||||
if (unlikely(!mapping))
|
||||
|
@ -831,9 +824,12 @@ int __set_page_dirty_buffers(struct page *page)
|
|||
bh = bh->b_this_page;
|
||||
} while (bh != head);
|
||||
}
|
||||
newly_dirty = !TestSetPageDirty(page);
|
||||
spin_unlock(&mapping->private_lock);
|
||||
|
||||
return __set_page_dirty(page, mapping, 1);
|
||||
if (newly_dirty)
|
||||
__set_page_dirty(page, mapping, 1);
|
||||
return newly_dirty;
|
||||
}
|
||||
EXPORT_SYMBOL(__set_page_dirty_buffers);
|
||||
|
||||
|
@ -1262,8 +1258,11 @@ void mark_buffer_dirty(struct buffer_head *bh)
|
|||
return;
|
||||
}
|
||||
|
||||
if (!test_set_buffer_dirty(bh))
|
||||
__set_page_dirty(bh->b_page, page_mapping(bh->b_page), 0);
|
||||
if (!test_set_buffer_dirty(bh)) {
|
||||
struct page *page = bh->b_page;
|
||||
if (!TestSetPageDirty(page))
|
||||
__set_page_dirty(page, page_mapping(page), 0);
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
|
|
Загрузка…
Ссылка в новой задаче