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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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51
fs/libfs.c
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@ -326,49 +326,6 @@ int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
return 0;
}
/**
* simple_setsize - handle core mm and vfs requirements for file size change
* @inode: inode
* @newsize: new file size
*
* Returns 0 on success, -error on failure.
*
* simple_setsize must be called with inode_mutex held.
*
* simple_setsize will check that the requested new size is OK (see
* inode_newsize_ok), and then will perform the necessary i_size update
* and pagecache truncation (if necessary). It will be typically be called
* from the filesystem's setattr function when ATTR_SIZE is passed in.
*
* The inode itself must have correct permissions and attributes to allow
* i_size to be changed, this function then just checks that the new size
* requested is valid.
*
* In the case of simple in-memory filesystems with inodes stored solely
* in the inode cache, and file data in the pagecache, nothing more needs
* to be done to satisfy a truncate request. Filesystems with on-disk
* blocks for example will need to free them in the case of truncate, in
* that case it may be easier not to use simple_setsize (but each of its
* components will likely be required at some point to update pagecache
* and inode etc).
*/
int simple_setsize(struct inode *inode, loff_t newsize)
{
loff_t oldsize;
int error;
error = inode_newsize_ok(inode, newsize);
if (error)
return error;
oldsize = inode->i_size;
i_size_write(inode, newsize);
truncate_pagecache(inode, oldsize, newsize);
return error;
}
EXPORT_SYMBOL(simple_setsize);
/**
* simple_setattr - setattr for simple filesystem
* @dentry: dentry
@ -394,12 +351,8 @@ int simple_setattr(struct dentry *dentry, struct iattr *iattr)
if (error)
return error;
if (iattr->ia_valid & ATTR_SIZE) {
error = simple_setsize(inode, iattr->ia_size);
if (error)
return error;
}
if (iattr->ia_valid & ATTR_SIZE)
truncate_setsize(inode, iattr->ia_size);
setattr_copy(inode, iattr);
mark_inode_dirty(inode);
return 0;