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locks: implement delegations

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Implement NFSv4 delegations at the vfs level using the new FL_DELEG lock
type.

Note nfsd is the only delegation user and is only using read
delegations.  Warn on any attempt to set a write delegation for now.
We'll come back to that case later.

Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
J. Bruce Fields 2012-03-05 13:18:59 -05:00 committed by Al Viro
parent 617588d518
commit df4e8d2c1d
2 changed files with 60 additions and 13 deletions
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53
fs/locks.c
View File

@ -1292,28 +1292,40 @@ static void time_out_leases(struct inode *inode)
}
}
static bool leases_conflict(struct file_lock *lease, struct file_lock *breaker)
{
if ((breaker->fl_flags & FL_DELEG) && (lease->fl_flags & FL_LEASE))
return false;
return locks_conflict(breaker, lease);
}
/**
* __break_lease - revoke all outstanding leases on file
* @inode: the inode of the file to return
* @mode: the open mode (read or write)
* @mode: O_RDONLY: break only write leases; O_WRONLY or O_RDWR:
* break all leases
* @type: FL_LEASE: break leases and delegations; FL_DELEG: break
* only delegations
*
* break_lease (inlined for speed) has checked there already is at least
* some kind of lock (maybe a lease) on this file. Leases are broken on
* a call to open() or truncate(). This function can sleep unless you
* specified %O_NONBLOCK to your open().
*/
int __break_lease(struct inode *inode, unsigned int mode)
int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
{
int error = 0;
struct file_lock *new_fl, *flock;
struct file_lock *fl;
unsigned long break_time;
int i_have_this_lease = 0;
bool lease_conflict = false;
int want_write = (mode & O_ACCMODE) != O_RDONLY;
new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
if (IS_ERR(new_fl))
return PTR_ERR(new_fl);
new_fl->fl_flags = type;
spin_lock(&inode->i_lock);
@ -1323,12 +1335,15 @@ int __break_lease(struct inode *inode, unsigned int mode)
if ((flock == NULL) || !IS_LEASE(flock))
goto out;
if (!locks_conflict(flock, new_fl))
goto out;
for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next)
for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) {
if (leases_conflict(fl, new_fl)) {
lease_conflict = true;
if (fl->fl_owner == current->files)
i_have_this_lease = 1;
}
}
if (!lease_conflict)
goto out;
break_time = 0;
if (lease_break_time > 0) {
@ -1338,6 +1353,8 @@ int __break_lease(struct inode *inode, unsigned int mode)
}
for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) {
if (!leases_conflict(fl, new_fl))
continue;
if (want_write) {
if (fl->fl_flags & FL_UNLOCK_PENDING)
continue;
@ -1379,7 +1396,7 @@ int __break_lease(struct inode *inode, unsigned int mode)
*/
for (flock = inode->i_flock; flock && IS_LEASE(flock);
flock = flock->fl_next) {
if (locks_conflict(new_fl, flock))
if (leases_conflict(new_fl, flock))
goto restart;
}
error = 0;
@ -1460,9 +1477,26 @@ static int generic_add_lease(struct file *filp, long arg, struct file_lock **flp
struct file_lock *fl, **before, **my_before = NULL, *lease;
struct dentry *dentry = filp->f_path.dentry;
struct inode *inode = dentry->d_inode;
bool is_deleg = (*flp)->fl_flags & FL_DELEG;
int error;
lease = *flp;
/*
* In the delegation case we need mutual exclusion with
* a number of operations that take the i_mutex. We trylock
* because delegations are an optional optimization, and if
* there's some chance of a conflict--we'd rather not
* bother, maybe that's a sign this just isn't a good file to
* hand out a delegation on.
*/
if (is_deleg && !mutex_trylock(&inode->i_mutex))
return -EAGAIN;
if (is_deleg && arg == F_WRLCK) {
/* Write delegations are not currently supported: */
WARN_ON_ONCE(1);
return -EINVAL;
}
error = -EAGAIN;
if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
@ -1514,9 +1548,10 @@ static int generic_add_lease(struct file *filp, long arg, struct file_lock **flp
goto out;
locks_insert_lock(before, lease);
return 0;
error = 0;
out:
if (is_deleg)
mutex_unlock(&inode->i_mutex);
return error;
}

18
include/linux/fs.h
View File

@ -1022,7 +1022,7 @@ extern int vfs_test_lock(struct file *, struct file_lock *);
extern int vfs_lock_file(struct file *, unsigned int, struct file_lock *, struct file_lock *);
extern int vfs_cancel_lock(struct file *filp, struct file_lock *fl);
extern int flock_lock_file_wait(struct file *filp, struct file_lock *fl);
extern int __break_lease(struct inode *inode, unsigned int flags);
extern int __break_lease(struct inode *inode, unsigned int flags, unsigned int type);
extern void lease_get_mtime(struct inode *, struct timespec *time);
extern int generic_setlease(struct file *, long, struct file_lock **);
extern int vfs_setlease(struct file *, long, struct file_lock **);
@ -1131,7 +1131,7 @@ static inline int flock_lock_file_wait(struct file *filp,
return -ENOLCK;
}
static inline int __break_lease(struct inode *inode, unsigned int mode)
static inline int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
{
return 0;
}
@ -1961,9 +1961,17 @@ static inline int locks_verify_truncate(struct inode *inode,
static inline int break_lease(struct inode *inode, unsigned int mode)
{
if (inode->i_flock)
return __break_lease(inode, mode);
return __break_lease(inode, mode, FL_LEASE);
return 0;
}
static inline int break_deleg(struct inode *inode, unsigned int mode)
{
if (inode->i_flock)
return __break_lease(inode, mode, FL_DELEG);
return 0;
}
#else /* !CONFIG_FILE_LOCKING */
static inline int locks_mandatory_locked(struct inode *inode)
{
@ -2003,6 +2011,10 @@ static inline int break_lease(struct inode *inode, unsigned int mode)
return 0;
}
static inline int break_deleg(struct inode *inode, unsigned int mode)
{
return 0;
}
#endif /* CONFIG_FILE_LOCKING */
/* fs/open.c */