Messages in this thread | | | From | Nikita Danilov <> | Date | Thu, 27 Nov 2003 20:45:44 +0300 | Subject | Re: [PATCH] fs/locks.c fcntl_setlease did not check if a file was opened for writing before granting a read lease |
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Jamie Lokier writes: > Joseph D. Wagner wrote: > > But I THINK this is how a patch would fix the problem, in theory. > > Sorry, it won't. > > > + if ((arg == F_RDLCK) > > + && ((dentry->d_flags & O_WRONLY) > > + || (dentry->d_flags & O_RDWR) > > + || (dentry->d_flags & O_CREAT) > > + || (dentry->d_flags & O_TRUNC) > > + || (inode->i_flags & O_WRONLY) > > + || (inode->i_flags & O_RDWR) > > + || (inode->i_flags & O_CREAT) > > + || (inode->i_flags & O_TRUNC))) > > + goto out_unlock; > > dentry->d_flags is a combination of the S_ flags, not O_ flags. > E.g. S_SYNC, S_NOATIME etc. > > inode->i_flags is a combination of the DCACHE_ flags. > E.g. DCACHE_AUTOFS_PENDING, DCACHE_REFERENCED tc.
I think it is other way around. ->i_flags are combined from S_SYNC (see, include/linux/fs.h:IS_IMMUTABLE(), for example), and ->d_flags are combined from DCACHE_*, latter is explicitly stated in include/linux/dcache.h
> > To detect if anyone has the file open for writing, you'll a new count > field which keeps track of writer references. Something like this: > > if ((arg == F_RDLCK) > && ((atomic_read(&inode->i_writer_count) != 0))) > > You'll also need to modify all the places where that needs to be > maintained. > > Btw, I'm not sure why the F_WRLCK case needs to check d_count and > i_count. Isn't it enough to check d_count? Won't all opens reference > the inode through a dentry?: > > > if ((arg == F_WRLCK) > > && ((atomic_read(&dentry->d_count) > 1) > > || (atomic_read(&inode->i_count) > 1))) > > -- Jamie
Nikita.
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