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File locking changes for v5.4

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Merge tag 'filelock-v5.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux

Pull file locking updates from Jeff Layton:
 "Just a couple of minor bugfixes, a revision to a tracepoint to account
  for some earlier changes to the internals, and a patch to add a
  pr_warn message when someone tries to mount a filesystem with '-o
  mand' on a kernel that has that support disabled"

* tag 'filelock-v5.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
  locks: fix a memory leak bug in __break_lease()
  locks: print a warning when mount fails due to lack of "mand" support
  locks: Fix procfs output for file leases
  locks: revise generic_add_lease tracepoint
This commit is contained in:
Linus Torvalds 2019-09-18 13:41:01 -07:00
commit d013cc800a
4 changed files with 31 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
Documentation/filesystems/mandatory-locking.txt
View File

@ -169,3 +169,13 @@ havoc if they lock crucial files. The way around it is to change the file
permissions (remove the setgid bit) before trying to read or write to it.
Of course, that might be a bit tricky if the system is hung :-(
7. The "mand" mount option
--------------------------
Mandatory locking is disabled on all filesystems by default, and must be
administratively enabled by mounting with "-o mand". That mount option
is only allowed if the mounting task has the CAP_SYS_ADMIN capability.
Since kernel v4.5, it is possible to disable mandatory locking
altogether by setting CONFIG_MANDATORY_FILE_LOCKING to "n". A kernel
with this disabled will reject attempts to mount filesystems with the
"mand" mount option with the error status EPERM.

11
fs/locks.c
View File

@ -1592,7 +1592,7 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
ctx = smp_load_acquire(&inode->i_flctx);
if (!ctx) {
WARN_ON_ONCE(1);
return error;
goto free_lock;
}
percpu_down_read(&file_rwsem);
@ -1672,6 +1672,7 @@ out:
spin_unlock(&ctx->flc_lock);
percpu_up_read(&file_rwsem);
locks_dispose_list(&dispose);
free_lock:
locks_free_lock(new_fl);
return error;
}
@ -2784,10 +2785,10 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ "
: (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
} else {
seq_printf(f, "%s ",
(lease_breaking(fl))
? (fl->fl_type == F_UNLCK) ? "UNLCK" : "READ "
: (fl->fl_type == F_WRLCK) ? "WRITE" : "READ ");
int type = IS_LEASE(fl) ? target_leasetype(fl) : fl->fl_type;
seq_printf(f, "%s ", (type == F_WRLCK) ? "WRITE" :
(type == F_RDLCK) ? "READ" : "UNLCK");
}
if (inode) {
/* userspace relies on this representation of dev_t */

11
fs/namespace.c
View File

@ -1643,13 +1643,18 @@ static inline bool may_mount(void)
return ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN);
}
#ifdef CONFIG_MANDATORY_FILE_LOCKING
static inline bool may_mandlock(void)
{
#ifndef CONFIG_MANDATORY_FILE_LOCKING
return false;
#endif
return capable(CAP_SYS_ADMIN);
}
#else
static inline bool may_mandlock(void)
{
pr_warn("VFS: \"mand\" mount option not supported");
return false;
}
#endif
/*
* Now umount can handle mount points as well as block devices.

14
include/trace/events/filelock.h
View File

@ -176,7 +176,7 @@ TRACE_EVENT(generic_add_lease,
TP_STRUCT__entry(
__field(unsigned long, i_ino)
__field(int, wcount)
__field(int, dcount)
__field(int, rcount)
__field(int, icount)
__field(dev_t, s_dev)
__field(fl_owner_t, fl_owner)
@ -188,16 +188,16 @@ TRACE_EVENT(generic_add_lease,
__entry->s_dev = inode->i_sb->s_dev;
__entry->i_ino = inode->i_ino;
__entry->wcount = atomic_read(&inode->i_writecount);
__entry->dcount = d_count(fl->fl_file->f_path.dentry);
__entry->rcount = atomic_read(&inode->i_readcount);
__entry->icount = atomic_read(&inode->i_count);
__entry->fl_owner = fl ? fl->fl_owner : NULL;
__entry->fl_flags = fl ? fl->fl_flags : 0;
__entry->fl_type = fl ? fl->fl_type : 0;
__entry->fl_owner = fl->fl_owner;
__entry->fl_flags = fl->fl_flags;
__entry->fl_type = fl->fl_type;
),
TP_printk("dev=0x%x:0x%x ino=0x%lx wcount=%d dcount=%d icount=%d fl_owner=0x%p fl_flags=%s fl_type=%s",
TP_printk("dev=0x%x:0x%x ino=0x%lx wcount=%d rcount=%d icount=%d fl_owner=0x%p fl_flags=%s fl_type=%s",
MAJOR(__entry->s_dev), MINOR(__entry->s_dev),
__entry->i_ino, __entry->wcount, __entry->dcount,
__entry->i_ino, __entry->wcount, __entry->rcount,
__entry->icount, __entry->fl_owner,
show_fl_flags(__entry->fl_flags),
show_fl_type(__entry->fl_type))