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Commit 1acf2e04 authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Linus Torvalds
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mm/nommu: share the i_mmap_rwsem 



Shrinking/truncate logic can call nommu_shrink_inode_mappings() to verify
that any shared mappings of the inode in question aren't broken (dead
zone).  afaict the only user being ramfs to handle the size change
attribute.

Pretty much a no-brainer to share the lock.

Signed-off-by: default avatarDavidlohr Bueso <dbueso@suse.de>
Acked-by: default avatar"Kirill A. Shutemov" <kirill@shutemov.name>
Acked-by: default avatarHugh Dickins <hughd@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: default avatarMel Gorman <mgorman@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d28eb9c8

mm/nommu.c

+4 −5
Original line number Diff line number Diff line
@@ -2094,14 +2094,14 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size, 
	high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;



	down_write(&nommu_region_sem);

	i_mmap_lock_write(inode->i_mapping);

	i_mmap_lock_read(inode->i_mapping);



	/* search for VMAs that fall within the dead zone */

	vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) {

		/* found one - only interested if it's shared out of the page

		 * cache */

		if (vma->vm_flags & VM_SHARED) {

			i_mmap_unlock_write(inode->i_mapping);

			i_mmap_unlock_read(inode->i_mapping);

			up_write(&nommu_region_sem);

			return -ETXTBSY; /* not quite true, but near enough */

		}
@@ -2113,8 +2113,7 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size, 
	 * we don't check for any regions that start beyond the EOF as there

	 * shouldn't be any

	 */

	vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap,

				  0, ULONG_MAX) {

	vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, 0, ULONG_MAX) {

		if (!(vma->vm_flags & VM_SHARED))

			continue;
@@ -2129,7 +2128,7 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size, 
		}

	}



	i_mmap_unlock_write(inode->i_mapping);

	i_mmap_unlock_read(inode->i_mapping);

	up_write(&nommu_region_sem);

	return 0;

}