[Add Nick to the CC] On Thu 28-06-12 19:01:15, Sha Zhengju wrote: > From: Sha Zhengju <handai.szj@xxxxxxxxxx> > > Commit a8e7d49a(Fix race in create_empty_buffers() vs __set_page_dirty_buffers()) > extracts TestSetPageDirty from __set_page_dirty and is far away from > account_page_dirtied.But it's better to make the two operations in one single > function to keep modular. > So in order to avoid the potential race mentioned in > commit a8e7d49a, we can hold private_lock until __set_page_dirty completes. So this is exactly what Nick suggested in the beginning (https://lkml.org/lkml/2009/3/19/169) > I guess there's no deadlock between ->private_lock and ->tree_lock by quick look. Yes and mm/filemap.c says that explicitly: * Lock ordering: * * ->i_mmap_mutex (truncate_pagecache) * ->private_lock (__free_pte->__set_page_dirty_buffers) * ->swap_lock (exclusive_swap_page, others) * ->mapping->tree_lock > > It's a prepare patch for following memcg dirty page accounting patches. > > Signed-off-by: Sha Zhengju <handai.szj@xxxxxxxxxx> The patch seems to be correct. Reviewed-by: Michal Hocko <mhocko@xxxxxxx> > --- > fs/buffer.c | 25 +++++++++++++------------ > 1 files changed, 13 insertions(+), 12 deletions(-) > > diff --git a/fs/buffer.c b/fs/buffer.c > index 838a9cf..e8d96b8 100644 > --- a/fs/buffer.c > +++ b/fs/buffer.c > @@ -610,9 +610,15 @@ 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 void __set_page_dirty(struct page *page, > +static int __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)); > @@ -622,6 +628,8 @@ static void __set_page_dirty(struct page *page, > } > spin_unlock_irq(&mapping->tree_lock); > __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); > + > + return 1; > } > > /* > @@ -667,11 +675,9 @@ int __set_page_dirty_buffers(struct page *page) > bh = bh->b_this_page; > } while (bh != head); > } > - newly_dirty = !TestSetPageDirty(page); > + newly_dirty = __set_page_dirty(page, mapping, 1); > spin_unlock(&mapping->private_lock); > > - if (newly_dirty) > - __set_page_dirty(page, mapping, 1); > return newly_dirty; > } > EXPORT_SYMBOL(__set_page_dirty_buffers); > @@ -1115,14 +1121,9 @@ void mark_buffer_dirty(struct buffer_head *bh) > return; > } > > - if (!test_set_buffer_dirty(bh)) { > - struct page *page = bh->b_page; > - if (!TestSetPageDirty(page)) { > - struct address_space *mapping = page_mapping(page); > - if (mapping) > - __set_page_dirty(page, mapping, 0); > - } > - } > + if (!test_set_buffer_dirty(bh)) > + __set_page_dirty(bh->b_page, page_mapping(bh->b_page), 0); > + > } > EXPORT_SYMBOL(mark_buffer_dirty); > > -- > 1.7.1 > -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>