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Commit 8a549bea authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
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mm: tidy vmtruncate_range and related functions 



Use consistent variable names in truncate_pagecache(), truncate_setsize(),
vmtruncate() and vmtruncate_range().

unmap_mapping_range() and vmtruncate_range() have mismatched interfaces:
don't change either, but make the vmtruncates more precise about what they
expect unmap_mapping_range() to do.

vmtruncate_range() is currently called only with page-aligned start and
end+1: can handle unaligned start, but unaligned end+1 would hit BUG_ON in
truncate_inode_pages_range() (lacks partial clearing of the end page).

Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 85821aab

mm/truncate.c

+17 −14
Original line number Diff line number Diff line
@@ -531,8 +531,8 @@ EXPORT_SYMBOL_GPL(invalidate_inode_pages2); 
/**

 * truncate_pagecache - unmap and remove pagecache that has been truncated

 * @inode: inode

 * @old: old file offset

 * @new: new file offset

 * @oldsize: old file size

 * @newsize: new file size

 *

 * inode's new i_size must already be written before truncate_pagecache

 * is called.
@@ -544,9 +544,10 @@ EXPORT_SYMBOL_GPL(invalidate_inode_pages2); 
 * situations such as writepage being called for a page that has already

 * had its underlying blocks deallocated.

 */

void truncate_pagecache(struct inode *inode, loff_t old, loff_t new)

void truncate_pagecache(struct inode *inode, loff_t oldsize, loff_t newsize)

{

	struct address_space *mapping = inode->i_mapping;

	loff_t holebegin = round_up(newsize, PAGE_SIZE);



	/*

	 * unmap_mapping_range is called twice, first simply for
@@ -557,9 +558,9 @@ void truncate_pagecache(struct inode *inode, loff_t old, loff_t new) 
	 * truncate_inode_pages finishes, hence the second

	 * unmap_mapping_range call must be made for correctness.

	 */

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

	truncate_inode_pages(mapping, new);

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

	unmap_mapping_range(mapping, holebegin, 0, 1);

	truncate_inode_pages(mapping, newsize);

	unmap_mapping_range(mapping, holebegin, 0, 1);

}

EXPORT_SYMBOL(truncate_pagecache);
@@ -589,29 +590,31 @@ EXPORT_SYMBOL(truncate_setsize); 
/**

 * vmtruncate - unmap mappings "freed" by truncate() syscall

 * @inode: inode of the file used

 * @offset: file offset to start truncating

 * @newsize: file offset to start truncating

 *

 * This function is deprecated and truncate_setsize or truncate_pagecache

 * should be used instead, together with filesystem specific block truncation.

 */

int vmtruncate(struct inode *inode, loff_t offset)

int vmtruncate(struct inode *inode, loff_t newsize)

{

	int error;



	error = inode_newsize_ok(inode, offset);

	error = inode_newsize_ok(inode, newsize);

	if (error)

		return error;



	truncate_setsize(inode, offset);

	truncate_setsize(inode, newsize);

	if (inode->i_op->truncate)

		inode->i_op->truncate(inode);

	return 0;

}

EXPORT_SYMBOL(vmtruncate);



int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)

int vmtruncate_range(struct inode *inode, loff_t lstart, loff_t lend)

{

	struct address_space *mapping = inode->i_mapping;

	loff_t holebegin = round_up(lstart, PAGE_SIZE);

	loff_t holelen = 1 + lend - holebegin;



	/*

	 * If the underlying filesystem is not going to provide
@@ -623,10 +626,10 @@ int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end) 


	mutex_lock(&inode->i_mutex);

	inode_dio_wait(inode);

	unmap_mapping_range(mapping, offset, (end - offset), 1);

	inode->i_op->truncate_range(inode, offset, end);

	unmap_mapping_range(mapping, holebegin, holelen, 1);

	inode->i_op->truncate_range(inode, lstart, lend);

	/* unmap again to remove racily COWed private pages */

	unmap_mapping_range(mapping, offset, (end - offset), 1);

	unmap_mapping_range(mapping, holebegin, holelen, 1);

	mutex_unlock(&inode->i_mutex);



	return 0;