1 files changed, 154 insertions, 107 deletions

diff --git a/block/blk-settings.c b/block/blk-settings.c
index 66d4aa8799b7..f5ed5a1187ba 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -8,6 +8,9 @@
 #include <linux/blkdev.h>
 #include <linux/bootmem.h>      /* for max_pfn/max_low_pfn */
 #include <linux/gcd.h>
+#include <linux/lcm.h>
+#include <linux/jiffies.h>
+#include <linux/gfp.h>
 
 #include "blk.h"
 
@@ -90,13 +93,16 @@ EXPORT_SYMBOL_GPL(blk_queue_lld_busy);
  */
 void blk_set_default_limits(struct queue_limits *lim)
 {
-        lim->max_phys_segments = MAX_PHYS_SEGMENTS;
-        lim->max_hw_segments = MAX_HW_SEGMENTS;
+        lim->max_segments = BLK_MAX_SEGMENTS;
         lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
-        lim->max_segment_size = MAX_SEGMENT_SIZE;
+        lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
         lim->max_sectors = BLK_DEF_MAX_SECTORS;
         lim->max_hw_sectors = INT_MAX;
-        lim->max_discard_sectors = SAFE_MAX_SECTORS;
+        lim->max_discard_sectors = 0;
+        lim->discard_granularity = 0;
+        lim->discard_alignment = 0;
+        lim->discard_misaligned = 0;
+        lim->discard_zeroes_data = -1;
         lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
         lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT);
         lim->alignment_offset = 0;
@@ -141,7 +147,7 @@ void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn)
         q->nr_batching = BLK_BATCH_REQ;
 
         q->unplug_thresh = 4;           /* hmm */
-        q->unplug_delay = (3 * HZ) / 1000;      /* 3 milliseconds */
+        q->unplug_delay = msecs_to_jiffies(3);  /* 3 milliseconds */
         if (q->unplug_delay == 0)
                 q->unplug_delay = 1;
 
@@ -149,7 +155,7 @@ void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn)
         q->unplug_timer.data = (unsigned long)q;
 
         blk_set_default_limits(&q->limits);
-        blk_queue_max_sectors(q, SAFE_MAX_SECTORS);
+        blk_queue_max_hw_sectors(q, BLK_SAFE_MAX_SECTORS);
 
         /*
          * If the caller didn't supply a lock, fall back to our embedded
@@ -205,37 +211,32 @@ void blk_queue_bounce_limit(struct request_queue *q, u64 dma_mask)
 EXPORT_SYMBOL(blk_queue_bounce_limit);
 
 /**
- * blk_queue_max_sectors - set max sectors for a request for this queue
+ * blk_queue_max_hw_sectors - set max sectors for a request for this queue
  * @q:  the request queue for the device
- * @max_sectors:  max sectors in the usual 512b unit
+ * @max_hw_sectors:  max hardware sectors in the usual 512b unit
  *
  * Description:
- *    Enables a low level driver to set an upper limit on the size of
- *    received requests.
+ *    Enables a low level driver to set a hard upper limit,
+ *    max_hw_sectors, on the size of requests.  max_hw_sectors is set by
+ *    the device driver based upon the combined capabilities of I/O
+ *    controller and storage device.
+ *
+ *    max_sectors is a soft limit imposed by the block layer for
+ *    filesystem type requests.  This value can be overridden on a
+ *    per-device basis in /sys/block/<device>/queue/max_sectors_kb.
+ *    The soft limit can not exceed max_hw_sectors.
  **/
-void blk_queue_max_sectors(struct request_queue *q, unsigned int max_sectors)
+void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors)
 {
-        if ((max_sectors << 9) < PAGE_CACHE_SIZE) {
-                max_sectors = 1 << (PAGE_CACHE_SHIFT - 9);
+        if ((max_hw_sectors << 9) < PAGE_CACHE_SIZE) {
+                max_hw_sectors = 1 << (PAGE_CACHE_SHIFT - 9);
                 printk(KERN_INFO "%s: set to minimum %d\n",
-                       __func__, max_sectors);
+                       __func__, max_hw_sectors);
         }
 
-        if (BLK_DEF_MAX_SECTORS > max_sectors)
-                q->limits.max_hw_sectors = q->limits.max_sectors = max_sectors;
-        else {
-                q->limits.max_sectors = BLK_DEF_MAX_SECTORS;
-                q->limits.max_hw_sectors = max_sectors;
-        }
-}
-EXPORT_SYMBOL(blk_queue_max_sectors);
-
-void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_sectors)
-{
-        if (BLK_DEF_MAX_SECTORS > max_sectors)
-                q->limits.max_hw_sectors = BLK_DEF_MAX_SECTORS;
-        else
-                q->limits.max_hw_sectors = max_sectors;
+        q->limits.max_hw_sectors = max_hw_sectors;
+        q->limits.max_sectors = min_t(unsigned int, max_hw_sectors,
+                                      BLK_DEF_MAX_SECTORS);
 }
 EXPORT_SYMBOL(blk_queue_max_hw_sectors);
 
@@ -252,41 +253,15 @@ void blk_queue_max_discard_sectors(struct request_queue *q,
 EXPORT_SYMBOL(blk_queue_max_discard_sectors);
 
 /**
- * blk_queue_max_phys_segments - set max phys segments for a request for this queue
- * @q:  the request queue for the device
- * @max_segments:  max number of segments
- *
- * Description:
- *    Enables a low level driver to set an upper limit on the number of
- *    physical data segments in a request.  This would be the largest sized
- *    scatter list the driver could handle.
- **/
-void blk_queue_max_phys_segments(struct request_queue *q,
-                                 unsigned short max_segments)
-{
-        if (!max_segments) {
-                max_segments = 1;
-                printk(KERN_INFO "%s: set to minimum %d\n",
-                       __func__, max_segments);
-        }
-
-        q->limits.max_phys_segments = max_segments;
-}
-EXPORT_SYMBOL(blk_queue_max_phys_segments);
-
-/**
- * blk_queue_max_hw_segments - set max hw segments for a request for this queue
+ * blk_queue_max_segments - set max hw segments for a request for this queue
  * @q:  the request queue for the device
  * @max_segments:  max number of segments
  *
  * Description:
  *    Enables a low level driver to set an upper limit on the number of
- *    hw data segments in a request.  This would be the largest number of
- *    address/length pairs the host adapter can actually give at once
- *    to the device.
+ *    hw data segments in a request.
  **/
-void blk_queue_max_hw_segments(struct request_queue *q,
-                               unsigned short max_segments)
+void blk_queue_max_segments(struct request_queue *q, unsigned short max_segments)
 {
         if (!max_segments) {
                 max_segments = 1;
@@ -294,9 +269,9 @@ void blk_queue_max_hw_segments(struct request_queue *q,
                        __func__, max_segments);
         }
 
-        q->limits.max_hw_segments = max_segments;
+        q->limits.max_segments = max_segments;
 }
-EXPORT_SYMBOL(blk_queue_max_hw_segments);
+EXPORT_SYMBOL(blk_queue_max_segments);
 
 /**
  * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
@@ -490,18 +465,30 @@ EXPORT_SYMBOL(blk_queue_stack_limits);
 
 /**
  * blk_stack_limits - adjust queue_limits for stacked devices
- * @t:  the stacking driver limits (top)
- * @b:  the underlying queue limits (bottom)
- * @offset:  offset to beginning of data within component device
+ * @t:  the stacking driver limits (top device)
+ * @b:  the underlying queue limits (bottom, component device)
+ * @start:  first data sector within component device
  *
  * Description:
- *    Merges two queue_limit structs.  Returns 0 if alignment didn't
- *    change.  Returns -1 if adding the bottom device caused
- *    misalignment.
+ *    This function is used by stacking drivers like MD and DM to ensure
+ *    that all component devices have compatible block sizes and
+ *    alignments.  The stacking driver must provide a queue_limits
+ *    struct (top) and then iteratively call the stacking function for
+ *    all component (bottom) devices.  The stacking function will
+ *    attempt to combine the values and ensure proper alignment.
+ *
+ *    Returns 0 if the top and bottom queue_limits are compatible.  The
+ *    top device's block sizes and alignment offsets may be adjusted to
+ *    ensure alignment with the bottom device. If no compatible sizes
+ *    and alignments exist, -1 is returned and the resulting top
+ *    queue_limits will have the misaligned flag set to indicate that
+ *    the alignment_offset is undefined.
  */
 int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
-                     sector_t offset)
+                     sector_t start)
 {
+        unsigned int top, bottom, alignment, ret = 0;
+
         t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors);
         t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors);
         t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn);
@@ -509,15 +496,31 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
         t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask,
                                             b->seg_boundary_mask);
 
-        t->max_phys_segments = min_not_zero(t->max_phys_segments,
-                                            b->max_phys_segments);
-
-        t->max_hw_segments = min_not_zero(t->max_hw_segments,
-                                          b->max_hw_segments);
+        t->max_segments = min_not_zero(t->max_segments, b->max_segments);
 
         t->max_segment_size = min_not_zero(t->max_segment_size,
                                            b->max_segment_size);
 
+        t->misaligned |= b->misaligned;
+
+        alignment = queue_limit_alignment_offset(b, start);
+
+        /* Bottom device has different alignment.  Check that it is
+         * compatible with the current top alignment.
+         */
+        if (t->alignment_offset != alignment) {
+
+                top = max(t->physical_block_size, t->io_min)
+                        + t->alignment_offset;
+                bottom = max(b->physical_block_size, b->io_min) + alignment;
+
+                /* Verify that top and bottom intervals line up */
+                if (max(top, bottom) & (min(top, bottom) - 1)) {
+                        t->misaligned = 1;
+                        ret = -1;
+                }
+        }
+
         t->logical_block_size = max(t->logical_block_size,
                                     b->logical_block_size);
 
@@ -525,50 +528,99 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
                                      b->physical_block_size);
 
         t->io_min = max(t->io_min, b->io_min);
+        t->io_opt = lcm(t->io_opt, b->io_opt);
+
         t->no_cluster |= b->no_cluster;
+        t->discard_zeroes_data &= b->discard_zeroes_data;
 
-        /* Bottom device offset aligned? */
-        if (offset &&
-            (offset & (b->physical_block_size - 1)) != b->alignment_offset) {
+        /* Physical block size a multiple of the logical block size? */
+        if (t->physical_block_size & (t->logical_block_size - 1)) {
+                t->physical_block_size = t->logical_block_size;
                 t->misaligned = 1;
-                return -1;
+                ret = -1;
         }
 
-        /* If top has no alignment offset, inherit from bottom */
-        if (!t->alignment_offset)
-                t->alignment_offset =
-                        b->alignment_offset & (b->physical_block_size - 1);
+        /* Minimum I/O a multiple of the physical block size? */
+        if (t->io_min & (t->physical_block_size - 1)) {
+                t->io_min = t->physical_block_size;
+                t->misaligned = 1;
+                ret = -1;
+        }
 
-        /* Top device aligned on logical block boundary? */
-        if (t->alignment_offset & (t->logical_block_size - 1)) {
+        /* Optimal I/O a multiple of the physical block size? */
+        if (t->io_opt & (t->physical_block_size - 1)) {
+                t->io_opt = 0;
                 t->misaligned = 1;
-                return -1;
+                ret = -1;
         }
 
-        /* Find lcm() of optimal I/O size */
-        if (t->io_opt && b->io_opt)
-                t->io_opt = (t->io_opt * b->io_opt) / gcd(t->io_opt, b->io_opt);
-        else if (b->io_opt)
-                t->io_opt = b->io_opt;
+        /* Find lowest common alignment_offset */
+        t->alignment_offset = lcm(t->alignment_offset, alignment)
+                & (max(t->physical_block_size, t->io_min) - 1);
+
+        /* Verify that new alignment_offset is on a logical block boundary */
+        if (t->alignment_offset & (t->logical_block_size - 1)) {
+                t->misaligned = 1;
+                ret = -1;
+        }
 
-        /* Verify that optimal I/O size is a multiple of io_min */
-        if (t->io_min && t->io_opt % t->io_min)
-                return -1;
+        /* Discard alignment and granularity */
+        if (b->discard_granularity) {
+                alignment = queue_limit_discard_alignment(b, start);
+
+                if (t->discard_granularity != 0 &&
+                    t->discard_alignment != alignment) {
+                        top = t->discard_granularity + t->discard_alignment;
+                        bottom = b->discard_granularity + alignment;
+
+                        /* Verify that top and bottom intervals line up */
+                        if (max(top, bottom) & (min(top, bottom) - 1))
+                                t->discard_misaligned = 1;
+                }
+
+                t->max_discard_sectors = min_not_zero(t->max_discard_sectors,
+                                                      b->max_discard_sectors);
+                t->discard_granularity = max(t->discard_granularity,
+                                             b->discard_granularity);
+                t->discard_alignment = lcm(t->discard_alignment, alignment) &
+                        (t->discard_granularity - 1);
+        }
 
-        return 0;
+        return ret;
 }
 EXPORT_SYMBOL(blk_stack_limits);
 
 /**
+ * bdev_stack_limits - adjust queue limits for stacked drivers
+ * @t:  the stacking driver limits (top device)
+ * @bdev:  the component block_device (bottom)
+ * @start:  first data sector within component device
+ *
+ * Description:
+ *    Merges queue limits for a top device and a block_device.  Returns
+ *    0 if alignment didn't change.  Returns -1 if adding the bottom
+ *    device caused misalignment.
+ */
+int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev,
+                      sector_t start)
+{
+        struct request_queue *bq = bdev_get_queue(bdev);
+
+        start += get_start_sect(bdev);
+
+        return blk_stack_limits(t, &bq->limits, start);
+}
+EXPORT_SYMBOL(bdev_stack_limits);
+
+/**
  * disk_stack_limits - adjust queue limits for stacked drivers
  * @disk:  MD/DM gendisk (top)
  * @bdev:  the underlying block device (bottom)
  * @offset:  offset to beginning of data within component device
  *
  * Description:
- *    Merges the limits for two queues.  Returns 0 if alignment
- *    didn't change.  Returns -1 if adding the bottom device caused
- *    misalignment.
+ *    Merges the limits for a top level gendisk and a bottom level
+ *    block_device.
  */
 void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,
                        sector_t offset)
@@ -576,9 +628,7 @@ void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,
         struct request_queue *t = disk->queue;
         struct request_queue *b = bdev_get_queue(bdev);
 
-        offset += get_start_sect(bdev) << 9;
-
-        if (blk_stack_limits(&t->limits, &b->limits, offset) < 0) {
+        if (bdev_stack_limits(&t->limits, bdev, offset >> 9) < 0) {
                 char top[BDEVNAME_SIZE], bottom[BDEVNAME_SIZE];
 
                 disk_name(disk, 0, top);
@@ -650,22 +700,19 @@ EXPORT_SYMBOL(blk_queue_update_dma_pad);
  * does is adjust the queue so that the buf is always appended
  * silently to the scatterlist.
  *
- * Note: This routine adjusts max_hw_segments to make room for
- * appending the drain buffer.  If you call
- * blk_queue_max_hw_segments() or blk_queue_max_phys_segments() after
- * calling this routine, you must set the limit to one fewer than your
- * device can support otherwise there won't be room for the drain
- * buffer.
+ * Note: This routine adjusts max_hw_segments to make room for appending
+ * the drain buffer.  If you call blk_queue_max_segments() after calling
+ * this routine, you must set the limit to one fewer than your device
+ * can support otherwise there won't be room for the drain buffer.
  */
 int blk_queue_dma_drain(struct request_queue *q,
                                dma_drain_needed_fn *dma_drain_needed,
                                void *buf, unsigned int size)
 {
-        if (queue_max_hw_segments(q) < 2 || queue_max_phys_segments(q) < 2)
+        if (queue_max_segments(q) < 2)
                 return -EINVAL;
         /* make room for appending the drain */
-        blk_queue_max_hw_segments(q, queue_max_hw_segments(q) - 1);
-        blk_queue_max_phys_segments(q, queue_max_phys_segments(q) - 1);
+        blk_queue_max_segments(q, queue_max_segments(q) - 1);
         q->dma_drain_needed = dma_drain_needed;
         q->dma_drain_buffer = buf;
         q->dma_drain_size = size;