[lc-checkins] CVS: linux/mm filemap.c,1.22,1.23

[Rodrigo S. de C. <rc...@us...>]

Update of /cvsroot/linuxcompressed/linux/mm
In directory usw-pr-cvs1:/tmp/cvs-serv7375/mm

Modified Files:
	filemap.c 
Log Message:
- Fixed another bug reported by Paolo Ciarrocchi. In this case, the bug
would result in a deadlock. It was caused by an allocation in
__find_lock_page_helper() function that didn't take into account the
gfp_mask of the caller function (since the gfp_mask wasn't passed as
parameter). Therefore we might call that function from somewhere whose
gfp_mask was GFP_NOFS and even then start writing out fragments, deadlocking
the kernel. To fix it, the allocation was removed from this function. The
only callers were __find_lock_page and find_or_create_page(). The latter one
doesn't need the __find_lock_page_helper() to check compressed cache, since
it already checks it itself. The former now does that by itself too.



Index: filemap.c
===================================================================
RCS file: /cvsroot/linuxcompressed/linux/mm/filemap.c,v
retrieving revision 1.22
retrieving revision 1.23
diff -C2 -r1.22 -r1.23
*** filemap.c	21 Mar 2002 19:24:17 -0000	1.22
--- filemap.c	28 Mar 2002 13:13:03 -0000	1.23
***************
*** 737,752 ****
  
  	if (!add_to_page_cache_unique(page, mapping, offset, hash)) {
! 		int comp_err, error = 0;
! 		
! 		comp_err = read_comp_cache(mapping, offset, page);
! 		switch (comp_err) {
! 		case -ENOENT:
  			error = mapping->a_ops->readpage(file, page);
- 		case 0:
- 			break;
- 		default:
- 			BUG();
- 		}
- 		
  		page_cache_release(page);
  		return error;
--- 737,743 ----
  
  	if (!add_to_page_cache_unique(page, mapping, offset, hash)) {
! 		int error = 0;
! 		if (read_comp_cache(mapping, offset, page))
  			error = mapping->a_ops->readpage(file, page);
  		page_cache_release(page);
  		return error;
***************
*** 964,968 ****
  					unsigned long offset, struct page *hash)
  {
! 	struct page *page, * cached_page = NULL;
  
  	/*
--- 955,959 ----
  					unsigned long offset, struct page *hash)
  {
! 	struct page *page;
  
  	/*
***************
*** 987,995 ****
  		}
  	}
! 	else {
  		if (!cached_page) {
  			comp_cache_fragment_t * fragment;			
  			if (find_comp_page(mapping, offset, &fragment))
  				goto out;
  			cached_page = page_cache_alloc(mapping);
  			goto repeat;
--- 978,1002 ----
  		}
  	}
! 	return page;
! }
! 
! /*
!  * Same as the above, but lock the page too, verifying that
!  * it's still valid once we own it.
!  */
! struct page * __find_lock_page (struct address_space *mapping,
! 				unsigned long offset, struct page **hash)
! {
! 	struct page *page, * cached_page = NULL;
! 
!  repeat:
! 	spin_lock(&pagecache_lock);
! 	page = __find_lock_page_helper(mapping, offset, *hash);
! 	if (!page) {
  		if (!cached_page) {
  			comp_cache_fragment_t * fragment;			
  			if (find_comp_page(mapping, offset, &fragment))
  				goto out;
+ 			spin_unlock(&pagecache_lock);
  			cached_page = page_cache_alloc(mapping);
  			goto repeat;
***************
*** 1012,1030 ****
   out:
  	if (cached_page)
! 		page_cache_release(cached_page);
! 	return page;
! }
! 
! /*
!  * Same as the above, but lock the page too, verifying that
!  * it's still valid once we own it.
!  */
! struct page * __find_lock_page (struct address_space *mapping,
! 				unsigned long offset, struct page **hash)
! {
! 	struct page *page;
! 
! 	spin_lock(&pagecache_lock);
! 	page = __find_lock_page_helper(mapping, offset, *hash);
  	spin_unlock(&pagecache_lock);
  	return page;
--- 1019,1023 ----
   out:
  	if (cached_page)
! 		page_cache_release(cached_page);	
  	spin_unlock(&pagecache_lock);
  	return page;