Commit f2db1971 authored by Michal Hocko's avatar Michal Hocko Committed by Linus Torvalds
Browse files

jbd2: get rid of superfluous __GFP_REPEAT

jbd2_alloc is explicit about its allocation preferences wrt.  the
allocation size.  Sub page allocations go to the slab allocator and
larger are using either the page allocator or vmalloc.  This is all good
but the logic is unnecessarily complex.

1) as per Ted, the vmalloc fallback is a left-over:

 : jbd2_alloc is only passed in the bh->b_size, which can't be PAGE_SIZE, so
 : the code path that calls vmalloc() should never get called.  When we
 : conveted jbd2_alloc() to suppor sub-page size allocations in commit
 : d2eecb03, there was an assumption that it could be called with a size
 : greater than PAGE_SIZE, but that's certaily not true today.

Moreover vmalloc allocation might even lead to a deadlock because the
callers expect GFP_NOFS context while vmalloc is GFP_KERNEL.

2) __GFP_REPEAT for requests <= PAGE_ALLOC_COSTLY_ORDER is ignored
   since the flag was introduced.

Let's simplify the code flow and use the slab allocator for sub-page
requests and the page allocator for others.  Even though order > 0 is
not currently used as per above leave that option open.

Link: http://lkml.kernel.org/r/1464599699-30131-18-git-send-email-mhocko@kernel.org


Signed-off-by: default avatarMichal Hocko <mhocko@suse.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a830627b
......@@ -2329,18 +2329,10 @@ void *jbd2_alloc(size_t size, gfp_t flags)
BUG_ON(size & (size-1)); /* Must be a power of 2 */
flags |= __GFP_REPEAT;
if (size == PAGE_SIZE)
ptr = (void *)__get_free_pages(flags, 0);
else if (size > PAGE_SIZE) {
int order = get_order(size);
if (order < 3)
ptr = (void *)__get_free_pages(flags, order);
else
ptr = vmalloc(size);
} else
if (size < PAGE_SIZE)
ptr = kmem_cache_alloc(get_slab(size), flags);
else
ptr = (void *)__get_free_pages(flags, get_order(size));
/* Check alignment; SLUB has gotten this wrong in the past,
* and this can lead to user data corruption! */
......@@ -2351,20 +2343,10 @@ void *jbd2_alloc(size_t size, gfp_t flags)
void jbd2_free(void *ptr, size_t size)
{
if (size == PAGE_SIZE) {
free_pages((unsigned long)ptr, 0);
return;
}
if (size > PAGE_SIZE) {
int order = get_order(size);
if (order < 3)
free_pages((unsigned long)ptr, order);
else
vfree(ptr);
return;
}
kmem_cache_free(get_slab(size), ptr);
if (size < PAGE_SIZE)
kmem_cache_free(get_slab(size), ptr);
else
free_pages((unsigned long)ptr, get_order(size));
};
/*
......
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