Re: [PATCH 1/3] smb: client: do not defer close open handles to deleted files

From: Shyam Prasad N <nspmangalore@gmail.com>
To: Steve French <smfrench@gmail.com>
Cc: meetakshisetiyaoss@gmail.com, sfrench@samba.org,
	pc@manguebit.com,  ronniesahlberg@gmail.com,
	sprasad@microsoft.com, tom@talpey.com,
	 linux-cifs@vger.kernel.org, linux-kernel@vger.kernel.org,
	 samba-technical@lists.samba.org, bharathsm.hsk@gmail.com,
	 Meetakshi Setiya <msetiya@microsoft.com>
Subject: Re: [PATCH 1/3] smb: client: do not defer close open handles to deleted files
Date: Sat, 10 Feb 2024 22:19:48 +0530	[thread overview]
Message-ID: <CANT5p=p+TYwH7yLH9+kvum0O5KjxKc9MrWtERCc7WCv_wzODQg@mail.gmail.com> (raw)
In-Reply-To: <CAH2r5mtdebsVFbOoQeYYL79GVXe0wn=GfdgVE1RkQrnowHOO5Q@mail.gmail.com>

On Sat, Feb 10, 2024 at 11:29 AM Steve French <smfrench@gmail.com> wrote:
>
> could we make the "file_is_deleted" a boolean instead of using up more
> space making it an int?

Meetakshi initially had it as a bool. I asked her to make it a bitmap,
just in case there can be other such flags that are needed in the
future.

>
> Alternatively - would it be possible to simply look at the file
> attributes to see if it was marked as deleted (ie we should already be
> setting ATTR_DELETE_ON_CLOSE)

It does not look like we use this attr anywhere today. (Am I missing something?)
Also, it looks like a flag that SMB uses in requests and responses.
I feel that it's better to keep a different flag for this purpose.

>
> On Fri, Feb 9, 2024 at 7:17 AM <meetakshisetiyaoss@gmail.com> wrote:
> >
> > From: Meetakshi Setiya <msetiya@microsoft.com>
> >
> > When a file/dentry has been deleted before closing all its open handles,
> > currently, closing them can add them to the deferred close list. This can
> > lead to problems in creating file with the same name when the file is
> > re-created before the deferred close completes. This issue was seen while
> > reusing a client's already existing lease on a file for compound operations
> > and xfstest 591 failed because of the deferred close handle that remained
> > valid even after the file was deleted and was being reused to create a file
> > with the same name. The server in this case returns an error on open with
> > STATUS_DELETE_PENDING. Recreating the file would fail till the deferred
> > handles are closed (duration specified in closetimeo).
> >
> > This patch fixes the issue by flagging all open handles for the deleted
> > file (file path to be precise) with FILE_DELETED at the end of the unlink
> > operation. A new field cflags has been introduced in the cifsFileInfo
> > structure to set the FILE_DELETED flag without interfering with the f_flags
> > field. This cflags field could be useful in the future for setting more
> > flags specific to cfile.
> > When doing close in cifs_close for each of these handles, check the
> > FILE_DELETED flag and do not defer close these handles if the corresponding
> > filepath has been deleted.
> >
> > Signed-off-by: Meetakshi Setiya <msetiya@microsoft.com>
> > ---
> >  fs/smb/client/cifsglob.h  |  3 +++
> >  fs/smb/client/cifsproto.h |  4 ++++
> >  fs/smb/client/file.c      |  3 ++-
> >  fs/smb/client/inode.c     |  2 ++
> >  fs/smb/client/misc.c      | 22 ++++++++++++++++++++++
> >  5 files changed, 33 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
> > index 16befff4cbb4..f6b4acdcdeb3 100644
> > --- a/fs/smb/client/cifsglob.h
> > +++ b/fs/smb/client/cifsglob.h
> > @@ -1398,6 +1398,8 @@ struct cifs_fid_locks {
> >         struct list_head locks;         /* locks held by fid above */
> >  };
> >
> > +#define FILE_DELETED 00000001
> > +
> >  struct cifsFileInfo {
> >         /* following two lists are protected by tcon->open_file_lock */
> >         struct list_head tlist; /* pointer to next fid owned by tcon */
> > @@ -1413,6 +1415,7 @@ struct cifsFileInfo {
> >         struct dentry *dentry;
> >         struct tcon_link *tlink;
> >         unsigned int f_flags;
> > +       unsigned int cflags;    /* flags for this file */
> >         bool invalidHandle:1;   /* file closed via session abend */
> >         bool swapfile:1;
> >         bool oplock_break_cancelled:1;
> > diff --git a/fs/smb/client/cifsproto.h b/fs/smb/client/cifsproto.h
> > index a841bf4967fa..f995b766b177 100644
> > --- a/fs/smb/client/cifsproto.h
> > +++ b/fs/smb/client/cifsproto.h
> > @@ -296,6 +296,10 @@ extern void cifs_close_all_deferred_files(struct cifs_tcon *cifs_tcon);
> >
> >  extern void cifs_close_deferred_file_under_dentry(struct cifs_tcon *cifs_tcon,
> >                                 const char *path);
> > +
> > +extern void cifs_mark_open_handles_for_deleted_file(struct cifs_tcon
> > +                               *cifs_tcon, const char *path);
> > +
> >  extern struct TCP_Server_Info *
> >  cifs_get_tcp_session(struct smb3_fs_context *ctx,
> >                      struct TCP_Server_Info *primary_server);
> > diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
> > index b75282c204da..91cf4d2df4de 100644
> > --- a/fs/smb/client/file.c
> > +++ b/fs/smb/client/file.c
> > @@ -483,6 +483,7 @@ struct cifsFileInfo *cifs_new_fileinfo(struct cifs_fid *fid, struct file *file,
> >         cfile->uid = current_fsuid();
> >         cfile->dentry = dget(dentry);
> >         cfile->f_flags = file->f_flags;
> > +       cfile->cflags = 0;
> >         cfile->invalidHandle = false;
> >         cfile->deferred_close_scheduled = false;
> >         cfile->tlink = cifs_get_tlink(tlink);
> > @@ -1085,7 +1086,7 @@ int cifs_close(struct inode *inode, struct file *file)
> >                 if ((cifs_sb->ctx->closetimeo && cinode->oplock == CIFS_CACHE_RHW_FLG)
> >                     && cinode->lease_granted &&
> >                     !test_bit(CIFS_INO_CLOSE_ON_LOCK, &cinode->flags) &&
> > -                   dclose) {
> > +                   dclose && !(cfile->cflags & FILE_DELETED)) {
> >                         if (test_and_clear_bit(CIFS_INO_MODIFIED_ATTR, &cinode->flags)) {
> >                                 inode_set_mtime_to_ts(inode,
> >                                                       inode_set_ctime_current(inode));
> > diff --git a/fs/smb/client/inode.c b/fs/smb/client/inode.c
> > index d02f8ba29cb5..8121b5b1aa22 100644
> > --- a/fs/smb/client/inode.c
> > +++ b/fs/smb/client/inode.c
> > @@ -1900,6 +1900,8 @@ int cifs_unlink(struct inode *dir, struct dentry *dentry)
> >         cifs_inode = CIFS_I(dir);
> >         CIFS_I(dir)->time = 0;  /* force revalidate of dir as well */
> >  unlink_out:
> > +       if (rc == 0)
> > +               cifs_mark_open_handles_for_deleted_file(tcon, full_path);
> >         free_dentry_path(page);
> >         kfree(attrs);
> >         free_xid(xid);
> > diff --git a/fs/smb/client/misc.c b/fs/smb/client/misc.c
> > index 0748d7b757b9..8e46dee1a36c 100644
> > --- a/fs/smb/client/misc.c
> > +++ b/fs/smb/client/misc.c
> > @@ -853,6 +853,28 @@ cifs_close_deferred_file_under_dentry(struct cifs_tcon *tcon, const char *path)
> >         free_dentry_path(page);
> >  }
> >
> > +/*
> > + * If a dentry has been deleted, all corresponding open handles should know that
> > + * so that we do not defer close them.
> > + */
> > +void cifs_mark_open_handles_for_deleted_file(struct cifs_tcon *tcon,
> > +                                            const char *path)
> > +{
> > +       struct cifsFileInfo *cfile;
> > +       void *page;
> > +       const char *full_path;
> > +
> > +       page = alloc_dentry_path();
> > +       spin_lock(&tcon->open_file_lock);
> > +       list_for_each_entry(cfile, &tcon->openFileList, tlist) {
> > +               full_path = build_path_from_dentry(cfile->dentry, page);
> > +               if (strcmp(full_path, path) == 0)
> > +                       cfile->cflags |= FILE_DELETED;
> > +       }
> > +       spin_unlock(&tcon->open_file_lock);
> > +       free_dentry_path(page);
> > +}
> > +
> >  /* parses DFS referral V3 structure
> >   * caller is responsible for freeing target_nodes
> >   * returns:
> > --
> > 2.39.2
> >
> >
>
>
> --
> Thanks,
>
> Steve

-- 
Regards,
Shyam