diff options
| -rw-r--r-- | fs/locks.c | 87 | ||||
| -rw-r--r-- | include/linux/fs.h | 7 |
2 files changed, 60 insertions, 34 deletions
diff --git a/fs/locks.c b/fs/locks.c index c4215418bca3..c525aa4de234 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -135,7 +135,16 @@ static bool lease_breaking(struct file_lock *fl) { - return fl->fl_flags & FL_INPROGRESS; + return fl->fl_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING); +} + +static int target_leasetype(struct file_lock *fl) +{ + if (fl->fl_flags & FL_UNLOCK_PENDING) + return F_UNLCK; + if (fl->fl_flags & FL_DOWNGRADE_PENDING) + return F_RDLCK; + return fl->fl_type; } int leases_enable = 1; @@ -1124,6 +1133,17 @@ int locks_mandatory_area(int read_write, struct inode *inode, EXPORT_SYMBOL(locks_mandatory_area); +static void lease_clear_pending(struct file_lock *fl, int arg) +{ + switch (arg) { + case F_UNLCK: + fl->fl_flags &= ~FL_UNLOCK_PENDING; + /* fall through: */ + case F_RDLCK: + fl->fl_flags &= ~FL_DOWNGRADE_PENDING; + } +} + /* We already had a lease on this file; just change its type */ int lease_modify(struct file_lock **before, int arg) { @@ -1132,7 +1152,7 @@ int lease_modify(struct file_lock **before, int arg) if (error) return error; - fl->fl_flags &= ~FL_INPROGRESS; + lease_clear_pending(fl, arg); locks_wake_up_blocks(fl); if (arg == F_UNLCK) locks_delete_lock(before); @@ -1141,6 +1161,14 @@ int lease_modify(struct file_lock **before, int arg) EXPORT_SYMBOL(lease_modify); +static bool past_time(unsigned long then) +{ + if (!then) + /* 0 is a special value meaning "this never expires": */ + return false; + return time_after(jiffies, then); +} + static void time_out_leases(struct inode *inode) { struct file_lock **before; @@ -1148,12 +1176,10 @@ static void time_out_leases(struct inode *inode) before = &inode->i_flock; while ((fl = *before) && IS_LEASE(fl) && lease_breaking(fl)) { - if ((fl->fl_break_time == 0) - || time_before(jiffies, fl->fl_break_time)) { - before = &fl->fl_next; - continue; - } - lease_modify(before, fl->fl_type); + if (past_time(fl->fl_downgrade_time)) + lease_modify(before, F_RDLCK); + if (past_time(fl->fl_break_time)) + lease_modify(before, F_UNLCK); if (fl == *before) /* lease_modify may have freed fl */ before = &fl->fl_next; } @@ -1171,7 +1197,7 @@ static void time_out_leases(struct inode *inode) */ int __break_lease(struct inode *inode, unsigned int mode) { - int error = 0, future; + int error = 0; struct file_lock *new_fl, *flock; struct file_lock *fl; unsigned long break_time; @@ -1188,24 +1214,13 @@ 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) if (fl->fl_owner == current->files) i_have_this_lease = 1; - if (want_write) { - /* If we want write access, we have to revoke any lease. */ - future = F_UNLCK; - } else if (lease_breaking(flock)) { - /* If the lease is already being broken, we just leave it */ - future = flock->fl_type; - } else if (flock->fl_type & F_WRLCK) { - /* Downgrade the exclusive lease to a read-only lease. */ - future = F_RDLCK; - } else { - /* the existing lease was read-only, so we can read too. */ - goto out; - } - if (IS_ERR(new_fl) && !i_have_this_lease && ((mode & O_NONBLOCK) == 0)) { error = PTR_ERR(new_fl); @@ -1220,13 +1235,18 @@ int __break_lease(struct inode *inode, unsigned int mode) } for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) { - if (fl->fl_type != future) { - fl->fl_type = future; - fl->fl_flags |= FL_INPROGRESS; + if (want_write) { + if (fl->fl_flags & FL_UNLOCK_PENDING) + continue; + fl->fl_flags |= FL_UNLOCK_PENDING; fl->fl_break_time = break_time; - /* lease must have lmops break callback */ - fl->fl_lmops->lm_break(fl); + } else { + if (lease_breaking(flock)) + continue; + fl->fl_flags |= FL_DOWNGRADE_PENDING; + fl->fl_downgrade_time = break_time; } + fl->fl_lmops->lm_break(fl); } if (i_have_this_lease || (mode & O_NONBLOCK)) { @@ -1250,10 +1270,13 @@ restart: if (error >= 0) { if (error == 0) time_out_leases(inode); - /* Wait for the next lease that has not been broken yet */ + /* + * Wait for the next conflicting lease that has not been + * broken yet + */ for (flock = inode->i_flock; flock && IS_LEASE(flock); flock = flock->fl_next) { - if (lease_breaking(flock)) + if (locks_conflict(new_fl, flock)) goto restart; } error = 0; @@ -1321,7 +1344,7 @@ int fcntl_getlease(struct file *filp) for (fl = filp->f_path.dentry->d_inode->i_flock; fl && IS_LEASE(fl); fl = fl->fl_next) { if (fl->fl_file == filp) { - type = fl->fl_type; + type = target_leasetype(fl); break; } } @@ -1386,7 +1409,7 @@ int generic_setlease(struct file *filp, long arg, struct file_lock **flp) before = &fl->fl_next) { if (fl->fl_file == filp) my_before = before; - else if ((fl->fl_type == F_UNLCK) && lease_breaking(fl)) + else if (fl->fl_flags & FL_UNLOCK_PENDING) /* * Someone is in the process of opening this * file for writing so we may not take an diff --git a/include/linux/fs.h b/include/linux/fs.h index 327fdd4de85f..76460edf1648 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1065,7 +1065,8 @@ static inline int file_check_writeable(struct file *filp) #define FL_LEASE 32 /* lease held on this file */ #define FL_CLOSE 64 /* unlock on close */ #define FL_SLEEP 128 /* A blocking lock */ -#define FL_INPROGRESS 256 /* Lease is being broken */ +#define FL_DOWNGRADE_PENDING 256 /* Lease is being downgraded */ +#define FL_UNLOCK_PENDING 512 /* Lease is being broken */ /* * Special return value from posix_lock_file() and vfs_lock_file() for @@ -1122,7 +1123,9 @@ struct file_lock { loff_t fl_end; struct fasync_struct * fl_fasync; /* for lease break notifications */ - unsigned long fl_break_time; /* for nonblocking lease breaks */ + /* for lease breaks: */ + unsigned long fl_break_time; + unsigned long fl_downgrade_time; const struct file_lock_operations *fl_ops; /* Callbacks for filesystems */ const struct lock_manager_operations *fl_lmops; /* Callbacks for lockmanagers */ |