Attached updated patch to have this fix only for calls from readdir
i.e cifs_prime_dcache.
On Mon, Feb 26, 2024 at 10:44 AM Steve French <smfrench@xxxxxxxxx> wrote:
>
> My only worry is that perhaps we should make it more narrow (ie only
> when called from readdir ie cifs_prime_dcache() rather than also
> never updating it on query_info calls)
>
> On Sun, Feb 25, 2024 at 10:50 PM Bharath SM <bharathsm.hsk@xxxxxxxxx> wrote:
> >
> > In cases of large directories, the readdir operation may span multiple
> > round trips to retrieve contents. This introduces a potential race
> > condition in case of concurrent write and readdir operations. If the
> > readdir operation initiates before a write has been processed by the
> > server, it may update the file size attribute to an older value.
> > Address this issue by avoiding file size updates from server when a
> > read/write lease.
> >
> > Scenario:
> > 1) process1: open dir xyz
> > 2) process1: readdir instance 1 on xyz
> > 3) process2: create file.txt for write
> > 4) process2: write x bytes to file.txt
> > 5) process2: close file.txt
> > 6) process2: open file.txt for read
> > 7) process1: readdir 2 - overwrites file.txt inode size to 0
> > 8) process2: read contents of file.txt - bug, short read with 0 bytes
> >
> > Signed-off-by: Bharath SM <bharathsm@xxxxxxxxxxxxx>
> > ---
> > fs/smb/client/file.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
> > index f2db4a1f81ad..e742d0d0e579 100644
> > --- a/fs/smb/client/file.c
> > +++ b/fs/smb/client/file.c
> > @@ -2952,7 +2952,8 @@ bool is_size_safe_to_change(struct cifsInodeInfo *cifsInode, __u64 end_of_file)
> > if (!cifsInode)
> > return true;
> >
> > - if (is_inode_writable(cifsInode)) {
> > + if (is_inode_writable(cifsInode) ||
> > + ((cifsInode->oplock & CIFS_CACHE_RW_FLG) != 0)) {
> > /* This inode is open for write at least once */
> > struct cifs_sb_info *cifs_sb;
> >
> > --
> > 2.34.1
> >
>
>
> --
> Thanks,
>
> Steve
Attachment:
0001-cifs-prevent-updating-file-size-from-server-if-we-ha.patch
Description: Binary data
