1 files changed, 140 insertions, 83 deletions

diff --git a/fs/locks.c b/fs/locks.c
index 96b33989147d..3b0d05dcd7c1 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -133,6 +133,20 @@
 #define IS_FLOCK(fl)    (fl->fl_flags & FL_FLOCK)
 #define IS_LEASE(fl)    (fl->fl_flags & FL_LEASE)
 
+static bool lease_breaking(struct file_lock *fl)
+{
+        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;
 int lease_break_time = 45;
 
@@ -1119,6 +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)
 {
@@ -1127,6 +1152,7 @@ int lease_modify(struct file_lock **before, int arg)
 
         if (error)
                 return error;
+        lease_clear_pending(fl, arg);
         locks_wake_up_blocks(fl);
         if (arg == F_UNLCK)
                 locks_delete_lock(before);
@@ -1135,19 +1161,25 @@ 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;
         struct file_lock *fl;
 
         before = &inode->i_flock;
-        while ((fl = *before) && IS_LEASE(fl) && (fl->fl_type & F_INPROGRESS)) {
-                if ((fl->fl_break_time == 0)
-                                || time_before(jiffies, fl->fl_break_time)) {
-                        before = &fl->fl_next;
-                        continue;
-                }
-                lease_modify(before, fl->fl_type & ~F_INPROGRESS);
+        while ((fl = *before) && IS_LEASE(fl) && lease_breaking(fl)) {
+                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;
         }
@@ -1165,7 +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;
@@ -1182,24 +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 | F_INPROGRESS;
-        } else if (flock->fl_type & F_INPROGRESS) {
-                /* 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 | F_INPROGRESS;
-        } 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);
@@ -1214,12 +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;
+                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)) {
@@ -1243,10 +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 (flock->fl_type & F_INPROGRESS)
+                        if (locks_conflict(new_fl, flock))
                                 goto restart;
                 }
                 error = 0;
@@ -1314,7 +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 & ~F_INPROGRESS;
+                        type = target_leasetype(fl);
                         break;
                 }
         }
@@ -1322,50 +1352,23 @@ int fcntl_getlease(struct file *filp)
         return type;
 }
 
-/**
- *      generic_setlease        -       sets a lease on an open file
- *      @filp: file pointer
- *      @arg: type of lease to obtain
- *      @flp: input - file_lock to use, output - file_lock inserted
- *
- *      The (input) flp->fl_lmops->lm_break function is required
- *      by break_lease().
- *
- *      Called with file_lock_lock held.
- */
-int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
+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;
-        int error, rdlease_count = 0, wrlease_count = 0;
+        int error;
 
         lease = *flp;
 
-        error = -EACCES;
-        if ((current_fsuid() != inode->i_uid) && !capable(CAP_LEASE))
-                goto out;
-        error = -EINVAL;
-        if (!S_ISREG(inode->i_mode))
+        error = -EAGAIN;
+        if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
                 goto out;
-        error = security_file_lock(filp, arg);
-        if (error)
+        if ((arg == F_WRLCK)
+            && ((dentry->d_count > 1)
+                || (atomic_read(&inode->i_count) > 1)))
                 goto out;
 
-        time_out_leases(inode);
-
-        BUG_ON(!(*flp)->fl_lmops->lm_break);
-
-        if (arg != F_UNLCK) {
-                error = -EAGAIN;
-                if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
-                        goto out;
-                if ((arg == F_WRLCK)
-                    && ((dentry->d_count > 1)
-                        || (atomic_read(&inode->i_count) > 1)))
-                        goto out;
-        }
-
         /*
          * At this point, we know that if there is an exclusive
          * lease on this file, then we hold it on this filp
@@ -1374,27 +1377,28 @@ int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
          * then the file is not open by anyone (including us)
          * except for this filp.
          */
+        error = -EAGAIN;
         for (before = &inode->i_flock;
                         ((fl = *before) != NULL) && IS_LEASE(fl);
                         before = &fl->fl_next) {
-                if (fl->fl_file == filp)
+                if (fl->fl_file == filp) {
                         my_before = before;
-                else if (fl->fl_type == (F_INPROGRESS | F_UNLCK))
-                        /*
-                         * Someone is in the process of opening this
-                         * file for writing so we may not take an
-                         * exclusive lease on it.
-                         */
-                        wrlease_count++;
-                else
-                        rdlease_count++;
+                        continue;
+                }
+                /*
+                 * No exclusive leases if someone else has a lease on
+                 * this file:
+                 */
+                if (arg == F_WRLCK)
+                        goto out;
+                /*
+                 * Modifying our existing lease is OK, but no getting a
+                 * new lease if someone else is opening for write:
+                 */
+                if (fl->fl_flags & FL_UNLOCK_PENDING)
+                        goto out;
         }
 
-        error = -EAGAIN;
-        if ((arg == F_RDLCK && (wrlease_count > 0)) ||
-            (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0)))
-                goto out;
-
         if (my_before != NULL) {
                 error = lease->fl_lmops->lm_change(my_before, arg);
                 if (!error)
@@ -1402,9 +1406,6 @@ int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
                 goto out;
         }
 
-        if (arg == F_UNLCK)
-                goto out;
-
         error = -EINVAL;
         if (!leases_enable)
                 goto out;
@@ -1415,6 +1416,62 @@ int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
 out:
         return error;
 }
+
+int generic_delete_lease(struct file *filp, struct file_lock **flp)
+{
+        struct file_lock *fl, **before;
+        struct dentry *dentry = filp->f_path.dentry;
+        struct inode *inode = dentry->d_inode;
+
+        for (before = &inode->i_flock;
+                        ((fl = *before) != NULL) && IS_LEASE(fl);
+                        before = &fl->fl_next) {
+                if (fl->fl_file != filp)
+                        continue;
+                return (*flp)->fl_lmops->lm_change(before, F_UNLCK);
+        }
+        return -EAGAIN;
+}
+
+/**
+ *      generic_setlease        -       sets a lease on an open file
+ *      @filp: file pointer
+ *      @arg: type of lease to obtain
+ *      @flp: input - file_lock to use, output - file_lock inserted
+ *
+ *      The (input) flp->fl_lmops->lm_break function is required
+ *      by break_lease().
+ *
+ *      Called with file_lock_lock held.
+ */
+int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
+{
+        struct dentry *dentry = filp->f_path.dentry;
+        struct inode *inode = dentry->d_inode;
+        int error;
+
+        if ((current_fsuid() != inode->i_uid) && !capable(CAP_LEASE))
+                return -EACCES;
+        if (!S_ISREG(inode->i_mode))
+                return -EINVAL;
+        error = security_file_lock(filp, arg);
+        if (error)
+                return error;
+
+        time_out_leases(inode);
+
+        BUG_ON(!(*flp)->fl_lmops->lm_break);
+
+        switch (arg) {
+        case F_UNLCK:
+                return generic_delete_lease(filp, flp);
+        case F_RDLCK:
+        case F_WRLCK:
+                return generic_add_lease(filp, arg, flp);
+        default:
+                BUG();
+        }
+}
 EXPORT_SYMBOL(generic_setlease);
 
 static int __vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
@@ -2126,7 +2183,7 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
                 }
         } else if (IS_LEASE(fl)) {
                 seq_printf(f, "LEASE  ");
-                if (fl->fl_type & F_INPROGRESS)
+                if (lease_breaking(fl))
                         seq_printf(f, "BREAKING  ");
                 else if (fl->fl_file)
                         seq_printf(f, "ACTIVE    ");
@@ -2142,7 +2199,7 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
                                : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
         } else {
                 seq_printf(f, "%s ",
-                               (fl->fl_type & F_INPROGRESS)
+                               (lease_breaking(fl))
                                ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ "
                                : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ ");
         }