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Commit 84c4e5e6 authored by Matthew Wilcox's avatar Matthew Wilcox Committed by Linus Torvalds
Browse files

dax: improve comment about truncate race 



Jan Kara pointed out I should be more explicit here about the perils of
racing against truncate.  The comment is mostly the same as for the PTE
case.

Signed-off-by: default avatarMatthew Wilcox <willy@linux.intel.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ae18d6dc

fs/dax.c

+6 −1
Original line number Diff line number Diff line
@@ -553,7 +553,12 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, 
	if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE)

		goto fallback;



	/* Guard against a race with truncate */

	/*

	 * If a truncate happened while we were allocating blocks, we may

	 * leave blocks allocated to the file that are beyond EOF.  We can't

	 * take i_mutex here, so just leave them hanging; they'll be freed

	 * when the file is deleted.

	 */

	size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;

	if (pgoff >= size) {

		result = VM_FAULT_SIGBUS;