[PATCH] Fix some problems with truncate and mtime semantics.
SUS requires that when truncating a file to the size that it currently
is:
truncate and ftruncate should NOT modify ctime or mtime
O_TRUNC SHOULD modify ctime and mtime.
Currently mtime and ctime are always modified on most local
filesystems (side effect of ->truncate) or never modified (on NFS).
With this patch:
ATTR_CTIME|ATTR_MTIME are sent with ATTR_SIZE precisely when
an update of these times is required whether size changes or not
(via a new argument to do_truncate). This allows NFS to do
the right thing for O_TRUNC.
inode_setattr nolonger forces ATTR_MTIME|ATTR_CTIME when the ATTR_SIZE
sets the size to it's current value. This allows local filesystems
to do the right thing for f?truncate.
Also, the logic in inode_setattr is changed a bit so there are two return
points. One returns the error from vmtruncate if it failed, the other
returns 0 (there can be no other failure).
Finally, if vmtruncate succeeds, and ATTR_SIZE is the only change
requested, we now fall-through and mark_inode_dirty. If a filesystem did
not have a ->truncate function, then vmtruncate will have changed i_size,
without marking the inode as 'dirty', and I think this is wrong.
Signed-off-by: Neil Brown <neilb@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/attr.c b/fs/attr.c
index 67bcd9b..b347325 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -67,20 +67,12 @@
int inode_setattr(struct inode * inode, struct iattr * attr)
{
unsigned int ia_valid = attr->ia_valid;
- int error = 0;
- if (ia_valid & ATTR_SIZE) {
- if (attr->ia_size != i_size_read(inode)) {
- error = vmtruncate(inode, attr->ia_size);
- if (error || (ia_valid == ATTR_SIZE))
- goto out;
- } else {
- /*
- * We skipped the truncate but must still update
- * timestamps
- */
- ia_valid |= ATTR_MTIME|ATTR_CTIME;
- }
+ if (ia_valid & ATTR_SIZE &&
+ attr->ia_size != i_size_read(inode)) {
+ int error = vmtruncate(inode, attr->ia_size);
+ if (error)
+ return error;
}
if (ia_valid & ATTR_UID)
@@ -104,8 +96,8 @@
inode->i_mode = mode;
}
mark_inode_dirty(inode);
-out:
- return error;
+
+ return 0;
}
EXPORT_SYMBOL(inode_setattr);