Merge commit 'v2.6.34-rc5' into tracing/core

Merge reason: pick up latest -rc's.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

16 files changed, 173 insertions, 69 deletions

diff --git a/include/linux/ata.h b/include/linux/ata.h
index b4c85e2adef5..700c5b9b3583 100644
--- a/include/linux/ata.h
+++ b/include/linux/ata.h
@@ -1025,8 +1025,8 @@ static inline int ata_ok(u8 status)
 
 static inline int lba_28_ok(u64 block, u32 n_block)
 {
-        /* check the ending block number */
-        return ((block + n_block) < ((u64)1 << 28)) && (n_block <= 256);
+        /* check the ending block number: must be LESS THAN 0x0fffffff */
+        return ((block + n_block) < ((1 << 28) - 1)) && (n_block <= 256);
 }
 
 static inline int lba_48_ok(u64 block, u32 n_block)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index ebd22dbed861..6690e8bae7bb 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -158,7 +158,6 @@ enum rq_flag_bits {
 struct request {
         struct list_head queuelist;
         struct call_single_data csd;
-        int cpu;
 
         struct request_queue *q;
 
@@ -166,9 +165,11 @@ struct request {
         enum rq_cmd_type_bits cmd_type;
         unsigned long atomic_flags;
 
+        int cpu;
+
         /* the following two fields are internal, NEVER access directly */
-        sector_t __sector;              /* sector cursor */
         unsigned int __data_len;        /* total data len */
+        sector_t __sector;              /* sector cursor */
 
         struct bio *bio;
         struct bio *biotail;
@@ -201,20 +202,20 @@ struct request {
 
         unsigned short ioprio;
 
+        int ref_count;
+
         void *special;          /* opaque pointer available for LLD use */
         char *buffer;           /* kaddr of the current segment if available */
 
         int tag;
         int errors;
 
-        int ref_count;
-
         /*
          * when request is used as a packet command carrier
          */
-        unsigned short cmd_len;
         unsigned char __cmd[BLK_MAX_CDB];
         unsigned char *cmd;
+        unsigned short cmd_len;
 
         unsigned int extra_len; /* length of alignment and padding */
         unsigned int sense_len;
@@ -921,26 +922,7 @@ extern void blk_cleanup_queue(struct request_queue *);
 extern void blk_queue_make_request(struct request_queue *, make_request_fn *);
 extern void blk_queue_bounce_limit(struct request_queue *, u64);
 extern void blk_queue_max_hw_sectors(struct request_queue *, unsigned int);
-
-/* Temporary compatibility wrapper */
-static inline void blk_queue_max_sectors(struct request_queue *q, unsigned int max)
-{
-        blk_queue_max_hw_sectors(q, max);
-}
-
 extern void blk_queue_max_segments(struct request_queue *, unsigned short);
-
-static inline void blk_queue_max_phys_segments(struct request_queue *q, unsigned short max)
-{
-        blk_queue_max_segments(q, max);
-}
-
-static inline void blk_queue_max_hw_segments(struct request_queue *q, unsigned short max)
-{
-        blk_queue_max_segments(q, max);
-}
-
-
 extern void blk_queue_max_segment_size(struct request_queue *, unsigned int);
 extern void blk_queue_max_discard_sectors(struct request_queue *q,
                 unsigned int max_discard_sectors);
@@ -1030,11 +1012,6 @@ static inline int sb_issue_discard(struct super_block *sb,
 
 extern int blk_verify_command(unsigned char *cmd, fmode_t has_write_perm);
 
-#define MAX_PHYS_SEGMENTS 128
-#define MAX_HW_SEGMENTS 128
-#define SAFE_MAX_SECTORS 255
-#define MAX_SEGMENT_SIZE        65536
-
 enum blk_default_limits {
         BLK_MAX_SEGMENTS        = 128,
         BLK_SAFE_MAX_SECTORS    = 255,
diff --git a/include/linux/drbd.h b/include/linux/drbd.h
index 78962272338a..4341b1a97a34 100644
--- a/include/linux/drbd.h
+++ b/include/linux/drbd.h
@@ -56,7 +56,7 @@ extern const char *drbd_buildtag(void);
 #define REL_VERSION "8.3.7"
 #define API_VERSION 88
 #define PRO_VERSION_MIN 86
-#define PRO_VERSION_MAX 91
+#define PRO_VERSION_MAX 92
 
 
 enum drbd_io_error_p {
diff --git a/include/linux/drbd_nl.h b/include/linux/drbd_nl.h
index a4d82f895994..f7431a4ca608 100644
--- a/include/linux/drbd_nl.h
+++ b/include/linux/drbd_nl.h
@@ -12,7 +12,7 @@
 #endif
 
 NL_PACKET(primary, 1,
-       NL_BIT(          1,      T_MAY_IGNORE,   overwrite_peer)
+       NL_BIT(          1,      T_MAY_IGNORE,   primary_force)
 )
 
 NL_PACKET(secondary, 2, )
@@ -63,6 +63,7 @@ NL_PACKET(net_conf, 5,
         NL_BIT(         41,     T_MAY_IGNORE,   always_asbp)
         NL_BIT(         61,     T_MAY_IGNORE,   no_cork)
         NL_BIT(         62,     T_MANDATORY,    auto_sndbuf_size)
+        NL_BIT(         70,     T_MANDATORY,    dry_run)
 )
 
 NL_PACKET(disconnect, 6, )
diff --git a/include/linux/firewire-cdev.h b/include/linux/firewire-cdev.h
index 40b11013408e..81f3b14d5d76 100644
--- a/include/linux/firewire-cdev.h
+++ b/include/linux/firewire-cdev.h
@@ -1,21 +1,26 @@
 /*
  * Char device interface.
  *
- * Copyright (C) 2005-2006  Kristian Hoegsberg <krh@bitplanet.net>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ * Copyright (C) 2005-2007  Kristian Hoegsberg <krh@bitplanet.net>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * PRECISION INSIGHT AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
  */
 
 #ifndef _LINUX_FIREWIRE_CDEV_H
@@ -438,7 +443,7 @@ struct fw_cdev_remove_descriptor {
  * @type:       %FW_CDEV_ISO_CONTEXT_TRANSMIT or %FW_CDEV_ISO_CONTEXT_RECEIVE
  * @header_size: Header size to strip for receive contexts
  * @channel:    Channel to bind to
- * @speed:      Speed to transmit at
+ * @speed:      Speed for transmit contexts
  * @closure:    To be returned in &fw_cdev_event_iso_interrupt
  * @handle:     Handle to context, written back by kernel
  *
@@ -451,6 +456,9 @@ struct fw_cdev_remove_descriptor {
  * If a context was successfully created, the kernel writes back a handle to the
  * context, which must be passed in for subsequent operations on that context.
  *
+ * For receive contexts, @header_size must be at least 4 and must be a multiple
+ * of 4.
+ *
  * Note that the effect of a @header_size > 4 depends on
  * &fw_cdev_get_info.version, as documented at &fw_cdev_event_iso_interrupt.
  */
@@ -481,10 +489,34 @@ struct fw_cdev_create_iso_context {
  *
  * &struct fw_cdev_iso_packet is used to describe isochronous packet queues.
  *
- * Use the FW_CDEV_ISO_ macros to fill in @control.  The sy and tag fields are
- * specified by IEEE 1394a and IEC 61883.
- *
- * FIXME - finish this documentation
+ * Use the FW_CDEV_ISO_ macros to fill in @control.
+ *
+ * For transmit packets, the header length must be a multiple of 4 and specifies
+ * the numbers of bytes in @header that will be prepended to the packet's
+ * payload; these bytes are copied into the kernel and will not be accessed
+ * after the ioctl has returned.  The sy and tag fields are copied to the iso
+ * packet header (these fields are specified by IEEE 1394a and IEC 61883-1).
+ * The skip flag specifies that no packet is to be sent in a frame; when using
+ * this, all other fields except the interrupt flag must be zero.
+ *
+ * For receive packets, the header length must be a multiple of the context's
+ * header size; if the header length is larger than the context's header size,
+ * multiple packets are queued for this entry.  The sy and tag fields are
+ * ignored.  If the sync flag is set, the context drops all packets until
+ * a packet with a matching sy field is received (the sync value to wait for is
+ * specified in the &fw_cdev_start_iso structure).  The payload length defines
+ * how many payload bytes can be received for one packet (in addition to payload
+ * quadlets that have been defined as headers and are stripped and returned in
+ * the &fw_cdev_event_iso_interrupt structure).  If more bytes are received, the
+ * additional bytes are dropped.  If less bytes are received, the remaining
+ * bytes in this part of the payload buffer will not be written to, not even by
+ * the next packet, i.e., packets received in consecutive frames will not
+ * necessarily be consecutive in memory.  If an entry has queued multiple
+ * packets, the payload length is divided equally among them.
+ *
+ * When a packet with the interrupt flag set has been completed, the
+ * &fw_cdev_event_iso_interrupt event will be sent.  An entry that has queued
+ * multiple receive packets is completed when its last packet is completed.
  */
 struct fw_cdev_iso_packet {
         __u32 control;
@@ -501,7 +533,7 @@ struct fw_cdev_iso_packet {
  * Queue a number of isochronous packets for reception or transmission.
  * This ioctl takes a pointer to an array of &fw_cdev_iso_packet structs,
  * which describe how to transmit from or receive into a contiguous region
- * of a mmap()'ed payload buffer.  As part of the packet descriptors,
+ * of a mmap()'ed payload buffer.  As part of transmit packet descriptors,
  * a series of headers can be supplied, which will be prepended to the
  * payload during DMA.
  *
@@ -620,8 +652,8 @@ struct fw_cdev_get_cycle_timer2 {
  * instead of allocated.
  * An %FW_CDEV_EVENT_ISO_RESOURCE_DEALLOCATED event concludes this operation.
  *
- * To summarize, %FW_CDEV_IOC_DEALLOCATE_ISO_RESOURCE allocates iso resources
- * for the lifetime of the fd or handle.
+ * To summarize, %FW_CDEV_IOC_ALLOCATE_ISO_RESOURCE allocates iso resources
+ * for the lifetime of the fd or @handle.
  * In contrast, %FW_CDEV_IOC_ALLOCATE_ISO_RESOURCE_ONCE allocates iso resources
  * for the duration of a bus generation.
  *
diff --git a/include/linux/firewire-constants.h b/include/linux/firewire-constants.h
index b316770a43fd..9c63f06e67f2 100644
--- a/include/linux/firewire-constants.h
+++ b/include/linux/firewire-constants.h
@@ -1,3 +1,28 @@
+/*
+ * IEEE 1394 constants.
+ *
+ * Copyright (C) 2005-2007  Kristian Hoegsberg <krh@bitplanet.net>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * PRECISION INSIGHT AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
 #ifndef _LINUX_FIREWIRE_CONSTANTS_H
 #define _LINUX_FIREWIRE_CONSTANTS_H
 
@@ -21,7 +46,7 @@
 #define EXTCODE_WRAP_ADD                0x6
 #define EXTCODE_VENDOR_DEPENDENT        0x7
 
-/* Juju specific tcodes */
+/* Linux firewire-core (Juju) specific tcodes */
 #define TCODE_LOCK_MASK_SWAP            (0x10 | EXTCODE_MASK_SWAP)
 #define TCODE_LOCK_COMPARE_SWAP         (0x10 | EXTCODE_COMPARE_SWAP)
 #define TCODE_LOCK_FETCH_ADD            (0x10 | EXTCODE_FETCH_ADD)
@@ -36,7 +61,7 @@
 #define RCODE_TYPE_ERROR                0x6
 #define RCODE_ADDRESS_ERROR             0x7
 
-/* Juju specific rcodes */
+/* Linux firewire-core (Juju) specific rcodes */
 #define RCODE_SEND_ERROR                0x10
 #define RCODE_CANCELLED                 0x11
 #define RCODE_BUSY                      0x12
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 56b50514ab25..5f2f4c4d8fb0 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -109,7 +109,7 @@ struct hd_struct {
 };
 
 #define GENHD_FL_REMOVABLE                      1
-#define GENHD_FL_DRIVERFS                       2
+/* 2 is unused */
 #define GENHD_FL_MEDIA_CHANGE_NOTIFY            4
 #define GENHD_FL_CD                             8
 #define GENHD_FL_UP                             16
diff --git a/include/linux/i2o.h b/include/linux/i2o.h
index 87018dc5527d..9e7a12d6385d 100644
--- a/include/linux/i2o.h
+++ b/include/linux/i2o.h
@@ -782,7 +782,6 @@ extern int i2o_exec_lct_get(struct i2o_controller *);
 #define to_i2o_driver(drv) container_of(drv,struct i2o_driver, driver)
 #define to_i2o_device(dev) container_of(dev, struct i2o_device, device)
 #define to_i2o_controller(dev) container_of(dev, struct i2o_controller, device)
-#define kobj_to_i2o_device(kobj) to_i2o_device(container_of(kobj, struct device, kobj))
 
 /**
  *      i2o_out_to_virt - Turn an I2O message to a virtual address
diff --git a/include/linux/ide.h b/include/linux/ide.h
index 97e6ab435184..3239d1c10acb 100644
--- a/include/linux/ide.h
+++ b/include/linux/ide.h
@@ -1169,6 +1169,7 @@ extern void ide_stall_queue(ide_drive_t *drive, unsigned long timeout);
 extern void ide_timer_expiry(unsigned long);
 extern irqreturn_t ide_intr(int irq, void *dev_id);
 extern void do_ide_request(struct request_queue *);
+extern void ide_requeue_and_plug(ide_drive_t *drive, struct request *rq);
 
 void ide_init_disk(struct gendisk *, ide_drive_t *);
 
diff --git a/include/linux/input/matrix_keypad.h b/include/linux/input/matrix_keypad.h
index 3bd018baae20..c964cd7f436a 100644
--- a/include/linux/input/matrix_keypad.h
+++ b/include/linux/input/matrix_keypad.h
@@ -44,6 +44,7 @@ struct matrix_keymap_data {
  * @active_low: gpio polarity
  * @wakeup: controls whether the device should be set up as wakeup
  *      source
+ * @no_autorepeat: disable key autorepeat
  *
  * This structure represents platform-specific data that use used by
  * matrix_keypad driver to perform proper initialization.
@@ -64,6 +65,7 @@ struct matrix_keypad_platform_data {
 
         bool            active_low;
         bool            wakeup;
+        bool            no_autorepeat;
 };
 
 /**
diff --git a/include/linux/lcm.h b/include/linux/lcm.h
new file mode 100644
index 000000000000..7bf01d779b45
--- /dev/null
+++ b/include/linux/lcm.h
@@ -0,0 +1,8 @@
+#ifndef _LCM_H
+#define _LCM_H
+
+#include <linux/compiler.h>
+
+unsigned long lcm(unsigned long a, unsigned long b) __attribute_const__;
+
+#endif /* _LCM_H */
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 717a5e54eb1d..e82957acea56 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -176,6 +176,7 @@ struct nfs_server {
 #define NFS_CAP_ATIME           (1U << 11)
 #define NFS_CAP_CTIME           (1U << 12)
 #define NFS_CAP_MTIME           (1U << 13)
+#define NFS_CAP_POSIX_LOCK      (1U << 14)
 
 
 /* maximum number of slots to use */
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index c5da74918096..55ca73cf25e5 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -121,6 +121,13 @@ do {									\
  * (Note, rcu_assign_pointer and rcu_dereference are not needed to control
  * access to data items when inserting into or looking up from the radix tree)
  *
+ * Note that the value returned by radix_tree_tag_get() may not be relied upon
+ * if only the RCU read lock is held.  Functions to set/clear tags and to
+ * delete nodes running concurrently with it may affect its result such that
+ * two consecutive reads in the same locked section may return different
+ * values.  If reliability is required, modification functions must also be
+ * excluded from concurrency.
+ *
  * radix_tree_tagged is able to be called without locking or RCU.
  */
 
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 872a98e13d6a..07db2feb8572 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -101,10 +101,7 @@ extern struct lockdep_map rcu_sched_lock_map;
 # define rcu_read_release_sched() \
                 lock_release(&rcu_sched_lock_map, 1, _THIS_IP_)
 
-static inline int debug_lockdep_rcu_enabled(void)
-{
-        return likely(rcu_scheduler_active && debug_locks);
-}
+extern int debug_lockdep_rcu_enabled(void);
 
 /**
  * rcu_read_lock_held - might we be in RCU read-side critical section?
@@ -195,12 +192,30 @@ static inline int rcu_read_lock_sched_held(void)
 
 /**
  * rcu_dereference_check - rcu_dereference with debug checking
+ * @p: The pointer to read, prior to dereferencing
+ * @c: The conditions under which the dereference will take place
+ *
+ * Do an rcu_dereference(), but check that the conditions under which the
+ * dereference will take place are correct.  Typically the conditions indicate
+ * the various locking conditions that should be held at that point.  The check
+ * should return true if the conditions are satisfied.
+ *
+ * For example:
+ *
+ *      bar = rcu_dereference_check(foo->bar, rcu_read_lock_held() ||
+ *                                            lockdep_is_held(&foo->lock));
  *
- * Do an rcu_dereference(), but check that the context is correct.
- * For example, rcu_dereference_check(gp, rcu_read_lock_held()) to
- * ensure that the rcu_dereference_check() executes within an RCU
- * read-side critical section.  It is also possible to check for
- * locks being held, for example, by using lockdep_is_held().
+ * could be used to indicate to lockdep that foo->bar may only be dereferenced
+ * if either the RCU read lock is held, or that the lock required to replace
+ * the bar struct at foo->bar is held.
+ *
+ * Note that the list of conditions may also include indications of when a lock
+ * need not be held, for example during initialisation or destruction of the
+ * target struct:
+ *
+ *      bar = rcu_dereference_check(foo->bar, rcu_read_lock_held() ||
+ *                                            lockdep_is_held(&foo->lock) ||
+ *                                            atomic_read(&foo->usage) == 0);
  */
 #define rcu_dereference_check(p, c) \
         ({ \
@@ -209,13 +224,45 @@ static inline int rcu_read_lock_sched_held(void)
                 rcu_dereference_raw(p); \
         })
 
+/**
+ * rcu_dereference_protected - fetch RCU pointer when updates prevented
+ *
+ * Return the value of the specified RCU-protected pointer, but omit
+ * both the smp_read_barrier_depends() and the ACCESS_ONCE().  This
+ * is useful in cases where update-side locks prevent the value of the
+ * pointer from changing.  Please note that this primitive does -not-
+ * prevent the compiler from repeating this reference or combining it
+ * with other references, so it should not be used without protection
+ * of appropriate locks.
+ */
+#define rcu_dereference_protected(p, c) \
+        ({ \
+                if (debug_lockdep_rcu_enabled() && !(c)) \
+                        lockdep_rcu_dereference(__FILE__, __LINE__); \
+                (p); \
+        })
+
 #else /* #ifdef CONFIG_PROVE_RCU */
 
 #define rcu_dereference_check(p, c)     rcu_dereference_raw(p)
+#define rcu_dereference_protected(p, c) (p)
 
 #endif /* #else #ifdef CONFIG_PROVE_RCU */
 
 /**
+ * rcu_access_pointer - fetch RCU pointer with no dereferencing
+ *
+ * Return the value of the specified RCU-protected pointer, but omit the
+ * smp_read_barrier_depends() and keep the ACCESS_ONCE().  This is useful
+ * when the value of this pointer is accessed, but the pointer is not
+ * dereferenced, for example, when testing an RCU-protected pointer against
+ * NULL.  This may also be used in cases where update-side locks prevent
+ * the value of the pointer from changing, but rcu_dereference_protected()
+ * is a lighter-weight primitive for this use case.
+ */
+#define rcu_access_pointer(p)   ACCESS_ONCE(p)
+
+/**
  * rcu_read_lock - mark the beginning of an RCU read-side critical section.
  *
  * When synchronize_rcu() is invoked on one CPU while other CPUs
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 488446289cab..49d1247cd6d9 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -106,6 +106,7 @@ int kmem_cache_shrink(struct kmem_cache *);
 void kmem_cache_free(struct kmem_cache *, void *);
 unsigned int kmem_cache_size(struct kmem_cache *);
 const char *kmem_cache_name(struct kmem_cache *);
+int kern_ptr_validate(const void *ptr, unsigned long size);
 int kmem_ptr_validate(struct kmem_cache *cachep, const void *ptr);
 
 /*
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 76e8903cd204..36520ded3e06 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -34,6 +34,9 @@ struct writeback_control {
         enum writeback_sync_modes sync_mode;
         unsigned long *older_than_this; /* If !NULL, only write back inodes
                                            older than this */
+        unsigned long wb_start;         /* Time writeback_inodes_wb was
+                                           called. This is needed to avoid
+                                           extra jobs and livelock */
         long nr_to_write;               /* Write this many pages, and decrement
                                            this for each page written */
         long pages_skipped;             /* Pages which were not written */