Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-gh0-f170.google.com ([209.85.160.170]:61041 "EHLO mail-gh0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752669Ab3EJLKJ (ORCPT ); Fri, 10 May 2013 07:10:09 -0400 Received: by mail-gh0-f170.google.com with SMTP id z10so873165ghb.15 for ; Fri, 10 May 2013 04:10:08 -0700 (PDT) Date: Fri, 10 May 2013 07:09:59 -0400 From: Jeff Layton To: Pavel Shilovsky Cc: linux-kernel@vger.kernel.org, linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org, wine-devel@winehq.org Subject: Re: [PATCH v6 2/7] VFS: Add O_DENYDELETE support for VFS Message-ID: <20130510070959.0af3e35a@tlielax.poochiereds.net> In-Reply-To: <1366977861-27678-3-git-send-email-piastry@etersoft.ru> References: <1366977861-27678-1-git-send-email-piastry@etersoft.ru> <1366977861-27678-3-git-send-email-piastry@etersoft.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-nfs-owner@vger.kernel.org List-ID: On Fri, 26 Apr 2013 16:04:16 +0400 Pavel Shilovsky wrote: > Introduce new LOCK_DELETE flock flag that is suggested to be used > internally only to map O_DENYDELETE open flag: > > !O_DENYDELETE -> LOCK_DELETE | LOCK_MAND. > > Signed-off-by: Pavel Shilovsky > --- > fs/locks.c | 53 +++++++++++++++++++++++++++++++++------- > fs/namei.c | 3 +++ > include/linux/fs.h | 6 +++++ > include/uapi/asm-generic/fcntl.h | 1 + > 4 files changed, 54 insertions(+), 9 deletions(-) > > diff --git a/fs/locks.c b/fs/locks.c > index dbc5557..1cc68a9 100644 > --- a/fs/locks.c > +++ b/fs/locks.c > @@ -269,7 +269,7 @@ EXPORT_SYMBOL(locks_copy_lock); > > static inline int flock_translate_cmd(int cmd) { > if (cmd & LOCK_MAND) > - return cmd & (LOCK_MAND | LOCK_RW); > + return cmd & (LOCK_MAND | LOCK_RW | LOCK_DELETE); > switch (cmd) { > case LOCK_SH: > return F_RDLCK; > @@ -614,6 +614,8 @@ deny_flags_to_cmd(unsigned int flags) > cmd |= LOCK_READ; > if (!(flags & O_DENYWRITE)) > cmd |= LOCK_WRITE; > + if (!(flags & O_DENYDELETE)) > + cmd |= LOCK_DELETE; > > return cmd; > } > @@ -836,6 +838,31 @@ out: > return error; > } > > +int > +sharelock_may_delete(struct dentry *dentry) > +{ > + struct file_lock **before; > + int rc = 0; > + > + if (!IS_SHARELOCK(dentry->d_inode)) > + return rc; > + > + lock_flocks(); > + for_each_lock(dentry->d_inode, before) { > + struct file_lock *fl = *before; > + if (IS_POSIX(fl)) > + break; > + if (IS_LEASE(fl)) > + continue; > + if (fl->fl_type & LOCK_DELETE) > + continue; > + rc = 1; > + break; > + } > + unlock_flocks(); > + return rc; > +} > + > /* > * Determine if a file is allowed to be opened with specified access and share > * modes. Lock the file and return 0 if checks passed, otherwise return > @@ -850,10 +877,6 @@ sharelock_lock_file(struct file *filp) > if (!IS_SHARELOCK(filp->f_path.dentry->d_inode)) > return error; > > - /* Disable O_DENYDELETE support for now */ > - if (filp->f_flags & O_DENYDELETE) > - return -EINVAL; > - > error = flock_make_lock(filp, &lock, deny_flags_to_cmd(filp->f_flags)); > if (error) > return error; > @@ -1717,6 +1740,12 @@ SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd) > if (!f.file) > goto out; > > + /* LOCK_DELETE is defined to be translated from O_DENYDELETE only */ > + if (cmd & LOCK_DELETE) { > + error = -EINVAL; > + goto out; > + } > + > can_sleep = !(cmd & LOCK_NB); > cmd &= ~LOCK_NB; > unlock = (cmd == LOCK_UN); > @@ -2261,10 +2290,16 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl, > seq_printf(f, "UNKNOWN UNKNOWN "); > } > if (fl->fl_type & LOCK_MAND) { > - seq_printf(f, "%s ", > - (fl->fl_type & LOCK_READ) > - ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ " > - : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE "); > + if (fl->fl_type & LOCK_DELETE) > + seq_printf(f, "%s ", > + (fl->fl_type & LOCK_READ) ? > + (fl->fl_type & LOCK_WRITE) ? "RWDEL" : "RDDEL" : > + (fl->fl_type & LOCK_WRITE) ? "WRDEL" : "DEL "); > + else > + seq_printf(f, "%s ", > + (fl->fl_type & LOCK_READ) ? > + (fl->fl_type & LOCK_WRITE) ? "RW " : "READ " : > + (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE "); > } else { > seq_printf(f, "%s ", > (lease_breaking(fl)) > diff --git a/fs/namei.c b/fs/namei.c > index dd236fe..a404f7d 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -2220,6 +2220,7 @@ static inline int check_sticky(struct inode *dir, struct inode *inode) > * 9. We can't remove a root or mountpoint. > * 10. We don't allow removal of NFS sillyrenamed files; it's handled by > * nfs_async_unlink(). > + * 11. We can't do it if victim is locked by O_DENYDELETE sharelock. > */ > static int may_delete(struct inode *dir,struct dentry *victim,int isdir) > { > @@ -2250,6 +2251,8 @@ static int may_delete(struct inode *dir,struct dentry *victim,int isdir) > return -ENOENT; > if (victim->d_flags & DCACHE_NFSFS_RENAMED) > return -EBUSY; > + if (sharelock_may_delete(victim)) > + return -ESHAREDENIED; Is there a potential race here? You're holding the parent's i_mutex when setting a lock on this file, but you're not holding it when you test for it here. So it seems possible you could end up granting a O_DENYDELETE open on a file that is in the process of being deleted from the namespace. > return 0; > } > > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 24066d2..afd56b1 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -1006,6 +1006,7 @@ extern int lock_may_read(struct inode *, loff_t start, unsigned long count); > extern int lock_may_write(struct inode *, loff_t start, unsigned long count); > extern void locks_delete_block(struct file_lock *waiter); > extern int sharelock_lock_file(struct file *); > +extern int sharelock_may_delete(struct dentry *); > extern void lock_flocks(void); > extern void unlock_flocks(void); > #else /* !CONFIG_FILE_LOCKING */ > @@ -1159,6 +1160,11 @@ static inline int sharelock_lock_file(struct file *filp) > return 0; > } > > +static inline int sharelock_may_delete(struct dentry *dentry) > +{ > + return 0; > +} > + > static inline void lock_flocks(void) > { > } > diff --git a/include/uapi/asm-generic/fcntl.h b/include/uapi/asm-generic/fcntl.h > index 5ac0d49..a3e6349 100644 > --- a/include/uapi/asm-generic/fcntl.h > +++ b/include/uapi/asm-generic/fcntl.h > @@ -167,6 +167,7 @@ struct f_owner_ex { > blocking */ > #define LOCK_UN 8 /* remove lock */ > > +#define LOCK_DELETE 16 /* which allows to delete a file */ > #define LOCK_MAND 32 /* This is a mandatory flock ... */ > #define LOCK_READ 64 /* which allows concurrent read operations */ > #define LOCK_WRITE 128 /* which allows concurrent write operations */ -- Jeff Layton