(XFS_MMAPLOCK_SHARED | XFS_MMAPLOCK_EXCL));
ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
(XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
- ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_DEP_MASK)) == 0);
+ ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_SUBCLASS_MASK)) == 0);
if (lock_flags & XFS_IOLOCK_EXCL)
mrupdate_nested(&ip->i_iolock, XFS_IOLOCK_DEP(lock_flags));
(XFS_MMAPLOCK_SHARED | XFS_MMAPLOCK_EXCL));
ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
(XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
- ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_DEP_MASK)) == 0);
+ ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_SUBCLASS_MASK)) == 0);
if (lock_flags & XFS_IOLOCK_EXCL) {
if (!mrtryupdate(&ip->i_iolock))
(XFS_MMAPLOCK_SHARED | XFS_MMAPLOCK_EXCL));
ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
(XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
- ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_DEP_MASK)) == 0);
+ ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_SUBCLASS_MASK)) == 0);
ASSERT(lock_flags != 0);
if (lock_flags & XFS_IOLOCK_EXCL)
/*
* Bump the subclass so xfs_lock_inodes() acquires each lock with a different
- * value. This shouldn't be called for page fault locking, but we also need to
- * ensure we don't overrun the number of lockdep subclasses for the iolock or
- * mmaplock as that is limited to 12 by the mmap lock lockdep annotations.
+ * value. This can be called for any type of inode lock combination, including
+ * parent locking. Care must be taken to ensure we don't overrun the subclass
+ * storage fields in the class mask we build.
*/
static inline int
xfs_lock_inumorder(int lock_mode, int subclass)
{
+ int class = 0;
+
+ ASSERT(!(lock_mode & (XFS_ILOCK_PARENT | XFS_ILOCK_RTBITMAP |
+ XFS_ILOCK_RTSUM)));
+
if (lock_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL)) {
- ASSERT(subclass + XFS_LOCK_INUMORDER <
- (1 << (XFS_MMAPLOCK_SHIFT - XFS_IOLOCK_SHIFT)));
- lock_mode |= (subclass + XFS_LOCK_INUMORDER) << XFS_IOLOCK_SHIFT;
+ ASSERT(subclass <= XFS_IOLOCK_MAX_SUBCLASS);
+ ASSERT(subclass + XFS_IOLOCK_PARENT_VAL <
+ MAX_LOCKDEP_SUBCLASSES);
+ class += subclass << XFS_IOLOCK_SHIFT;
+ if (lock_mode & XFS_IOLOCK_PARENT)
+ class += XFS_IOLOCK_PARENT_VAL << XFS_IOLOCK_SHIFT;
}
if (lock_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) {
- ASSERT(subclass + XFS_LOCK_INUMORDER <
- (1 << (XFS_ILOCK_SHIFT - XFS_MMAPLOCK_SHIFT)));
- lock_mode |= (subclass + XFS_LOCK_INUMORDER) <<
- XFS_MMAPLOCK_SHIFT;
+ ASSERT(subclass <= XFS_MMAPLOCK_MAX_SUBCLASS);
+ class += subclass << XFS_MMAPLOCK_SHIFT;
}
- if (lock_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL))
- lock_mode |= (subclass + XFS_LOCK_INUMORDER) << XFS_ILOCK_SHIFT;
+ if (lock_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)) {
+ ASSERT(subclass <= XFS_ILOCK_MAX_SUBCLASS);
+ class += subclass << XFS_ILOCK_SHIFT;
+ }
- return lock_mode;
+ return (lock_mode & ~XFS_LOCK_SUBCLASS_MASK) | class;
}
/*
* transaction (such as truncate). This can result in deadlock since the long
* running trans might need to wait for the inode we just locked in order to
* push the tail and free space in the log.
+ *
+ * xfs_lock_inodes() can only be used to lock one type of lock at a time -
+ * the iolock, the mmaplock or the ilock, but not more than one at a time. If we
+ * lock more than one at a time, lockdep will report false positives saying we
+ * have violated locking orders.
*/
void
xfs_lock_inodes(
int attempts = 0, i, j, try_lock;
xfs_log_item_t *lp;
- /* currently supports between 2 and 5 inodes */
+ /*
+ * Currently supports between 2 and 5 inodes with exclusive locking. We
+ * support an arbitrary depth of locking here, but absolute limits on
+ * inodes depend on the the type of locking and the limits placed by
+ * lockdep annotations in xfs_lock_inumorder. These are all checked by
+ * the asserts.
+ */
ASSERT(ips && inodes >= 2 && inodes <= 5);
+ ASSERT(lock_mode & (XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL |
+ XFS_ILOCK_EXCL));
+ ASSERT(!(lock_mode & (XFS_IOLOCK_SHARED | XFS_MMAPLOCK_SHARED |
+ XFS_ILOCK_SHARED)));
+ ASSERT(!(lock_mode & XFS_IOLOCK_EXCL) ||
+ inodes <= XFS_IOLOCK_MAX_SUBCLASS + 1);
+ ASSERT(!(lock_mode & XFS_MMAPLOCK_EXCL) ||
+ inodes <= XFS_MMAPLOCK_MAX_SUBCLASS + 1);
+ ASSERT(!(lock_mode & XFS_ILOCK_EXCL) ||
+ inodes <= XFS_ILOCK_MAX_SUBCLASS + 1);
+
+ if (lock_mode & XFS_IOLOCK_EXCL) {
+ ASSERT(!(lock_mode & (XFS_MMAPLOCK_EXCL | XFS_ILOCK_EXCL)));
+ } else if (lock_mode & XFS_MMAPLOCK_EXCL)
+ ASSERT(!(lock_mode & XFS_ILOCK_EXCL));
try_lock = 0;
i = 0;
* Flags for lockdep annotations.
*
* XFS_LOCK_PARENT - for directory operations that require locking a
- * parent directory inode and a child entry inode. The parent gets locked
- * with this flag so it gets a lockdep subclass of 1 and the child entry
- * lock will have a lockdep subclass of 0.
+ * parent directory inode and a child entry inode. IOLOCK requires nesting,
+ * MMAPLOCK does not support this class, ILOCK requires a single subclass
+ * to differentiate parent from child.
*
* XFS_LOCK_RTBITMAP/XFS_LOCK_RTSUM - the realtime device bitmap and summary
* inodes do not participate in the normal lock order, and thus have their
* XFS_LOCK_INUMORDER - for locking several inodes at the some time
* with xfs_lock_inodes(). This flag is used as the starting subclass
* and each subsequent lock acquired will increment the subclass by one.
- * So the first lock acquired will have a lockdep subclass of 4, the
- * second lock will have a lockdep subclass of 5, and so on. It is
- * the responsibility of the class builder to shift this to the correct
- * portion of the lock_mode lockdep mask.
+ * However, MAX_LOCKDEP_SUBCLASSES == 8, which means we are greatly
+ * limited to the subclasses we can represent via nesting. We need at least
+ * 5 inodes nest depth for the ILOCK through rename, and we also have to support
+ * XFS_ILOCK_PARENT, which gives 6 subclasses. Then we have XFS_ILOCK_RTBITMAP
+ * and XFS_ILOCK_RTSUM, which are another 2 unique subclasses, so that's all
+ * 8 subclasses supported by lockdep.
+ *
+ * This also means we have to number the sub-classes in the lowest bits of
+ * the mask we keep, and we have to ensure we never exceed 3 bits of lockdep
+ * mask and we can't use bit-masking to build the subclasses. What a mess.
+ *
+ * Bit layout:
+ *
+ * Bit Lock Region
+ * 16-19 XFS_IOLOCK_SHIFT dependencies
+ * 20-23 XFS_MMAPLOCK_SHIFT dependencies
+ * 24-31 XFS_ILOCK_SHIFT dependencies
+ *
+ * IOLOCK values
+ *
+ * 0-3 subclass value
+ * 4-7 PARENT subclass values
+ *
+ * MMAPLOCK values
+ *
+ * 0-3 subclass value
+ * 4-7 unused
+ *
+ * ILOCK values
+ * 0-4 subclass values
+ * 5 PARENT subclass (not nestable)
+ * 6 RTBITMAP subclass (not nestable)
+ * 7 RTSUM subclass (not nestable)
+ *
*/
-#define XFS_LOCK_PARENT 1
-#define XFS_LOCK_RTBITMAP 2
-#define XFS_LOCK_RTSUM 3
-#define XFS_LOCK_INUMORDER 4
-
-#define XFS_IOLOCK_SHIFT 16
-#define XFS_IOLOCK_PARENT (XFS_LOCK_PARENT << XFS_IOLOCK_SHIFT)
-
-#define XFS_MMAPLOCK_SHIFT 20
-
-#define XFS_ILOCK_SHIFT 24
-#define XFS_ILOCK_PARENT (XFS_LOCK_PARENT << XFS_ILOCK_SHIFT)
-#define XFS_ILOCK_RTBITMAP (XFS_LOCK_RTBITMAP << XFS_ILOCK_SHIFT)
-#define XFS_ILOCK_RTSUM (XFS_LOCK_RTSUM << XFS_ILOCK_SHIFT)
-
-#define XFS_IOLOCK_DEP_MASK 0x000f0000
-#define XFS_MMAPLOCK_DEP_MASK 0x00f00000
-#define XFS_ILOCK_DEP_MASK 0xff000000
-#define XFS_LOCK_DEP_MASK (XFS_IOLOCK_DEP_MASK | \
+#define XFS_IOLOCK_SHIFT 16
+#define XFS_IOLOCK_PARENT_VAL 4
+#define XFS_IOLOCK_MAX_SUBCLASS (XFS_IOLOCK_PARENT_VAL - 1)
+#define XFS_IOLOCK_DEP_MASK 0x000f0000
+#define XFS_IOLOCK_PARENT (XFS_IOLOCK_PARENT_VAL << XFS_IOLOCK_SHIFT)
+
+#define XFS_MMAPLOCK_SHIFT 20
+#define XFS_MMAPLOCK_NUMORDER 0
+#define XFS_MMAPLOCK_MAX_SUBCLASS 3
+#define XFS_MMAPLOCK_DEP_MASK 0x00f00000
+
+#define XFS_ILOCK_SHIFT 24
+#define XFS_ILOCK_PARENT_VAL 5
+#define XFS_ILOCK_MAX_SUBCLASS (XFS_ILOCK_PARENT_VAL - 1)
+#define XFS_ILOCK_RTBITMAP_VAL 6
+#define XFS_ILOCK_RTSUM_VAL 7
+#define XFS_ILOCK_DEP_MASK 0xff000000
+#define XFS_ILOCK_PARENT (XFS_ILOCK_PARENT_VAL << XFS_ILOCK_SHIFT)
+#define XFS_ILOCK_RTBITMAP (XFS_ILOCK_RTBITMAP_VAL << XFS_ILOCK_SHIFT)
+#define XFS_ILOCK_RTSUM (XFS_ILOCK_RTSUM_VAL << XFS_ILOCK_SHIFT)
+
+#define XFS_LOCK_SUBCLASS_MASK (XFS_IOLOCK_DEP_MASK | \
XFS_MMAPLOCK_DEP_MASK | \
XFS_ILOCK_DEP_MASK)
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