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check ATTR_SIZE contraints in inode_change_ok

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Make sure we check the truncate constraints early on in ->setattr by adding
those checks to inode_change_ok.  Also clean up and document inode_change_ok
to make this obvious.

As a fallout we don't have to call inode_newsize_ok from simple_setsize and
simplify it down to a truncate_setsize which doesn't return an error.  This
simplifies a lot of setattr implementations and means we use truncate_setsize
almost everywhere.  Get rid of fat_setsize now that it's trivial and mark
ext2_setsize static to make the calling convention obvious.

Keep the inode_newsize_ok in vmtruncate for now as all callers need an
audit for its removal anyway.

Note: setattr code in ecryptfs doesn't call inode_change_ok at all and
needs a deeper audit, but that is left for later.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Christoph Hellwig
2010-06-04 11:30:04 +02:00
committed by Al Viro
parent db78b877f7
commit 2c27c65ed0
21 changed files with 108 additions and 156 deletions
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38
mm/truncate.c
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@@ -540,29 +540,49 @@ void truncate_pagecache(struct inode *inode, loff_t old, loff_t new)
}
EXPORT_SYMBOL(truncate_pagecache);
/**
* truncate_setsize - update inode and pagecache for a new file size
* @inode: inode
* @newsize: new file size
*
* truncate_setsize updastes i_size update and performs pagecache
* truncation (if necessary) for a file size updates. It will be
* typically be called from the filesystem's setattr function when
* ATTR_SIZE is passed in.
*
* Must be called with inode_mutex held and after all filesystem
* specific block truncation has been performed.
*/
void truncate_setsize(struct inode *inode, loff_t newsize)
{
loff_t oldsize;
oldsize = inode->i_size;
i_size_write(inode, newsize);
truncate_pagecache(inode, oldsize, newsize);
}
EXPORT_SYMBOL(truncate_setsize);
/**
* vmtruncate - unmap mappings "freed" by truncate() syscall
* @inode: inode of the file used
* @offset: file offset to start truncating
*
* NOTE! We have to be ready to update the memory sharing
* between the file and the memory map for a potential last
* incomplete page. Ugly, but necessary.
*
* This function is deprecated and simple_setsize or truncate_pagecache
* should be used instead.
* 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 error;
error = simple_setsize(inode, offset);
error = inode_newsize_ok(inode, offset);
if (error)
return error;
truncate_setsize(inode, offset);
if (inode->i_op->truncate)
inode->i_op->truncate(inode);
return error;
return 0;
}
EXPORT_SYMBOL(vmtruncate);