Hi,
12/15/2012 12:16 AM, Brian Foster пишет:
On 12/14/2012 10:21 AM, Maxim V. Patlasov wrote:
The patch improves error handling in fuse_direct_IO(): if we successfully
submitted several fuse requests on behalf of synchronous direct write
extending file and some of them failed, let's try to do our best to clean-up.
Signed-off-by: Maxim Patlasov <mpatla...@parallels.com>
---
fs/fuse/file.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++--
1 files changed, 53 insertions(+), 2 deletions(-)
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 05eed23..b6e9b8d 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -2340,6 +2340,53 @@ int fuse_notify_poll_wakeup(struct fuse_conn *fc,
return 0;
}
+static void fuse_do_truncate(struct file *file)
+{
+ struct fuse_file *ff = file->private_data;
+ struct inode *inode = file->f_mapping->host;
+ struct fuse_conn *fc = get_fuse_conn(inode);
+ struct fuse_req *req;
+ struct fuse_setattr_in inarg;
+ struct fuse_attr_out outarg;
+ int err;
+
+ req = fuse_get_req_nopages(fc);
+ if (IS_ERR(req)) {
+ printk(KERN_WARNING "failed to allocate req for truncate "
+ "(%ld)\n", PTR_ERR(req));
+ return;
+ }
+
+ memset(&inarg, 0, sizeof(inarg));
+ memset(&outarg, 0, sizeof(outarg));
+
+ inarg.valid |= FATTR_SIZE;
+ inarg.size = i_size_read(inode);
+
+ inarg.valid |= FATTR_FH;
+ inarg.fh = ff->fh;
+
+ req->in.h.opcode = FUSE_SETATTR;
+ req->in.h.nodeid = get_node_id(inode);
+ req->in.numargs = 1;
+ req->in.args[0].size = sizeof(inarg);
+ req->in.args[0].value = &inarg;
+ req->out.numargs = 1;
+ if (fc->minor < 9)
+ req->out.args[0].size = FUSE_COMPAT_ATTR_OUT_SIZE;
+ else
+ req->out.args[0].size = sizeof(outarg);
+ req->out.args[0].value = &outarg;
+
+ fuse_request_send(fc, req);
+ err = req->out.h.error;
+ fuse_put_request(fc, req);
+
+ if (err)
+ printk(KERN_WARNING "failed to truncate to %lld with error "
+ "%d\n", i_size_read(inode), err);
+}
+
fuse_do_truncate() looks fairly close to fuse_do_setattr(). Is there any
reason we couldn't make fuse_do_setattr() non-static, change the dentry
parameter to an inode and use that?
fuse_do_setattr() performs extra checks that fuse_do_truncate() needn't.
Some of them are harmless, some not: fuse_allow_task() may return 0 if
task credentials changed. E.g. super-user successfully opened a file,
then setuid(other_user_uid), then write(2) to the file. write(2) doesn't
check uid, but fuse_do_truncate() - via fuse_allow_task() - does.
This non-POSIX behaviour (ftruncate(2) returning -1 with errno==EACCES)
was introduced long time ago:
commit e57ac68378a287d6336d187b26971f35f7ee7251
Author: Miklos Szeredi <mszer...@suse.cz>
Date: Thu Oct 18 03:06:58 2007 -0700
fuse: fix allowing operations
The following operation didn't check if sending the request was
allowed:
setattr
listxattr
statfs
Some other operations don't explicitly do the check, but VFS calls
->permission() which checks this.
Signed-off-by: Miklos Szeredi <mszer...@suse.cz>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
and I'm not sure whether it was done intentionally or not. Maybe Miklos
could shed some light on it...
Thanks,
Maxim
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