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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 <[email protected]>
Signed-off-by: Al Viro <[email protected]>
This commit is contained in:
Christoph Hellwig 2010-06-04 11:30:04 +02:00 • committed by Al Viro
commit 2c27c65ed0
21 changed files with 108 additions and 156 deletions
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23
fs/ubifs/file.c
View file

@ -967,14 +967,15 @@ static int do_writepage(struct page *page, int len)
* the page locked, and it locks @ui_mutex. However, write-back does take inode
* @i_mutex, which means other VFS operations may be run on this inode at the
* same time. And the problematic one is truncation to smaller size, from where
* we have to call 'simple_setsize()', which first changes @inode->i_size, then
* we have to call 'truncate_setsize()', which first changes @inode->i_size, then
* drops the truncated pages. And while dropping the pages, it takes the page
* lock. This means that 'do_truncation()' cannot call 'simple_setsize()' with
* lock. This means that 'do_truncation()' cannot call 'truncate_setsize()' with
* @ui_mutex locked, because it would deadlock with 'ubifs_writepage()'. This
* means that @inode->i_size is changed while @ui_mutex is unlocked.
*
* XXX: with the new truncate the above is not true anymore, the simple_setsize
* calls can be replaced with the individual components.
* XXX(truncate): with the new truncate sequence this is not true anymore,
* and the calls to truncate_setsize can be move around freely. They should
* be moved to the very end of the truncate sequence.
*
* But in 'ubifs_writepage()' we have to guarantee that we do not write beyond
* inode size. How do we do this if @inode->i_size may became smaller while we
@ -1128,9 +1129,7 @@ static int do_truncation(struct ubifs_info *c, struct inode *inode,
budgeted = 0;
}
err = simple_setsize(inode, new_size);
if (err)
goto out_budg;
truncate_setsize(inode, new_size);
if (offset) {
pgoff_t index = new_size >> PAGE_CACHE_SHIFT;
@ -1217,16 +1216,14 @@ static int do_setattr(struct ubifs_info *c, struct inode *inode,
if (attr->ia_valid & ATTR_SIZE) {
dbg_gen("size %lld -> %lld", inode->i_size, new_size);
err = simple_setsize(inode, new_size);
if (err)
goto out;
truncate_setsize(inode, new_size);
}
mutex_lock(&ui->ui_mutex);
if (attr->ia_valid & ATTR_SIZE) {
/* Truncation changes inode [mc]time */
inode->i_mtime = inode->i_ctime = ubifs_current_time(inode);
/* 'simple_setsize()' changed @i_size, update @ui_size */
/* 'truncate_setsize()' changed @i_size, update @ui_size */
ui->ui_size = inode->i_size;
}
@ -1248,10 +1245,6 @@ static int do_setattr(struct ubifs_info *c, struct inode *inode,
if (IS_SYNC(inode))
err = inode->i_sb->s_op->write_inode(inode, NULL);
return err;
out:
ubifs_release_budget(c, &req);
return err;
}
int ubifs_setattr(struct dentry *dentry, struct iattr *attr)

2
fs/ubifs/ubifs.h
View file

@ -379,7 +379,7 @@ struct ubifs_gced_idx_leb {
* The @ui_size is a "shadow" variable for @inode->i_size and UBIFS uses
* @ui_size instead of @inode->i_size. The reason for this is that UBIFS cannot
* make sure @inode->i_size is always changed under @ui_mutex, because it
* cannot call 'simple_setsize()' with @ui_mutex locked, because it would deadlock
* cannot call 'truncate_setsize()' with @ui_mutex locked, because it would deadlock
* with 'ubifs_writepage()' (see file.c). All the other inode fields are
* changed under @ui_mutex, so they do not need "shadow" fields. Note, one
* could consider to rework locking and base it on "shadow" fields.