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 <piastry@xxxxxxxxxxx>
---
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;
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 */
--
1.8.1.5
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