Messages in this thread | | | Date | Thu, 27 Nov 2003 16:50:43 +0000 | From | Jamie Lokier <> | 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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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.
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)))
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