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Commit 61d5048f authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Linus Torvalds
Browse files

clean up vmtruncate 



vmtruncate is a twisted maze of gotos, this patch cleans it up to have a
proper if else for the two major cases of extending and truncating truncate
and thus makes it a lot more readable while keeping exactly the same
functinality.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1b1b32f2

mm/memory.c

+34 −35
Original line number Diff line number Diff line
@@ -1909,50 +1909,49 @@ EXPORT_SYMBOL(unmap_mapping_range); 
 */

int vmtruncate(struct inode * inode, loff_t offset)

{

	struct address_space *mapping = inode->i_mapping;

	if (inode->i_size < offset) {

		unsigned long limit;



	if (inode->i_size < offset)

		goto do_expand;

		limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;

		if (limit != RLIM_INFINITY && offset > limit)

			goto out_sig;

		if (offset > inode->i_sb->s_maxbytes)

			goto out_big;

		i_size_write(inode, offset);

	} else {

		struct address_space *mapping = inode->i_mapping;



		/*

	 * truncation of in-use swapfiles is disallowed - it would cause

	 * subsequent swapout to scribble on the now-freed blocks.

		 * truncation of in-use swapfiles is disallowed - it would

		 * cause subsequent swapout to scribble on the now-freed

		 * blocks.

		 */

		if (IS_SWAPFILE(inode))

		goto out_busy;

			return -ETXTBSY;

		i_size_write(inode, offset);



		/*

	 * unmap_mapping_range is called twice, first simply for efficiency

	 * so that truncate_inode_pages does fewer single-page unmaps. However

	 * after this first call, and before truncate_inode_pages finishes,

	 * it is possible for private pages to be COWed, which remain after

	 * truncate_inode_pages finishes, hence the second unmap_mapping_range

	 * call must be made for correctness.

		 * unmap_mapping_range is called twice, first simply for

		 * efficiency so that truncate_inode_pages does fewer

		 * single-page unmaps.  However after this first call, and

		 * before truncate_inode_pages finishes, it is possible for

		 * private pages to be COWed, which remain after

		 * truncate_inode_pages finishes, hence the second

		 * unmap_mapping_range call must be made for correctness.

		 */

		unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);

		truncate_inode_pages(mapping, offset);

		unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);

	goto out_truncate;



do_expand:

	limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;

	if (limit != RLIM_INFINITY && offset > limit)

		goto out_sig;

	if (offset > inode->i_sb->s_maxbytes)

		goto out_big;

	i_size_write(inode, offset);

	}



out_truncate:

	if (inode->i_op && inode->i_op->truncate)

		inode->i_op->truncate(inode);

	return 0;



out_sig:

	send_sig(SIGXFSZ, current, 0);

out_big:

	return -EFBIG;

out_busy:

	return -ETXTBSY;

}

EXPORT_SYMBOL(vmtruncate);