md/bitmap: prepare for storing write-intent-bitmap via dm-dirty-log.

This allows md/raid5 to fully work as a dm target.

Normally md uses a 'filemap' which contains a list of pages of bits
each of which may be written separately.
dm-log uses and all-or-nothing approach to writing the log, so
when using a dm-log, ->filemap is NULL and the flags normally stored
in filemap_attr are stored in ->logattrs instead.



Signed-off-by: NeilBrown <neilb@suse.de>

3 files changed, 99 insertions, 39 deletions

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 29a3c864e6b0..93765261c363 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -29,6 +29,7 @@
 #include "md.h"
 #include "bitmap.h"
 
+#include <linux/dm-dirty-log.h>
 /* debug macros */
 
 #define DEBUG 0
@@ -694,6 +695,8 @@ static inline unsigned long file_page_offset(struct bitmap *bitmap, unsigned lon
 static inline struct page *filemap_get_page(struct bitmap *bitmap,
                                         unsigned long chunk)
 {
+        if (bitmap->filemap == NULL)
+                return NULL;
         if (file_page_index(bitmap, chunk) >= bitmap->file_pages)
                 return NULL;
         return bitmap->filemap[file_page_index(bitmap, chunk)
@@ -793,19 +796,28 @@ enum bitmap_page_attr {
 static inline void set_page_attr(struct bitmap *bitmap, struct page *page,
                                 enum bitmap_page_attr attr)
 {
-        __set_bit((page->index<<2) + attr, bitmap->filemap_attr);
+        if (page)
+                __set_bit((page->index<<2) + attr, bitmap->filemap_attr);
+        else
+                __set_bit(attr, &bitmap->logattrs);
 }
 
 static inline void clear_page_attr(struct bitmap *bitmap, struct page *page,
                                 enum bitmap_page_attr attr)
 {
-        __clear_bit((page->index<<2) + attr, bitmap->filemap_attr);
+        if (page)
+                __clear_bit((page->index<<2) + attr, bitmap->filemap_attr);
+        else
+                __clear_bit(attr, &bitmap->logattrs);
 }
 
 static inline unsigned long test_page_attr(struct bitmap *bitmap, struct page *page,
                                            enum bitmap_page_attr attr)
 {
-        return test_bit((page->index<<2) + attr, bitmap->filemap_attr);
+        if (page)
+                return test_bit((page->index<<2) + attr, bitmap->filemap_attr);
+        else
+                return test_bit(attr, &bitmap->logattrs);
 }
 
 /*
@@ -818,27 +830,30 @@ static inline unsigned long test_page_attr(struct bitmap *bitmap, struct page *p
 static void bitmap_file_set_bit(struct bitmap *bitmap, sector_t block)
 {
         unsigned long bit;
-        struct page *page;
+        struct page *page = NULL;
         void *kaddr;
         unsigned long chunk = block >> CHUNK_BLOCK_SHIFT(bitmap);
 
-        if (!bitmap->filemap)
-                return;
-
-        page = filemap_get_page(bitmap, chunk);
-        if (!page)
-                return;
-        bit = file_page_offset(bitmap, chunk);
+        if (!bitmap->filemap) {
+                struct dm_dirty_log *log = bitmap->mddev->bitmap_info.log;
+                if (log)
+                        log->type->mark_region(log, chunk);
+        } else {
 
-        /* set the bit */
-        kaddr = kmap_atomic(page, KM_USER0);
-        if (bitmap->flags & BITMAP_HOSTENDIAN)
-                set_bit(bit, kaddr);
-        else
-                ext2_set_bit(bit, kaddr);
-        kunmap_atomic(kaddr, KM_USER0);
-        PRINTK("set file bit %lu page %lu\n", bit, page->index);
+                page = filemap_get_page(bitmap, chunk);
+                if (!page)
+                        return;
+                bit = file_page_offset(bitmap, chunk);
 
+                /* set the bit */
+                kaddr = kmap_atomic(page, KM_USER0);
+                if (bitmap->flags & BITMAP_HOSTENDIAN)
+                        set_bit(bit, kaddr);
+                else
+                        ext2_set_bit(bit, kaddr);
+                kunmap_atomic(kaddr, KM_USER0);
+                PRINTK("set file bit %lu page %lu\n", bit, page->index);
+        }
         /* record page number so it gets flushed to disk when unplug occurs */
         set_page_attr(bitmap, page, BITMAP_PAGE_DIRTY);
 }
@@ -855,6 +870,16 @@ void bitmap_unplug(struct bitmap *bitmap)
 
         if (!bitmap)
                 return;
+        if (!bitmap->filemap) {
+                /* Must be using a dirty_log */
+                struct dm_dirty_log *log = bitmap->mddev->bitmap_info.log;
+                dirty = test_and_clear_bit(BITMAP_PAGE_DIRTY, &bitmap->logattrs);
+                need_write = test_and_clear_bit(BITMAP_PAGE_NEEDWRITE, &bitmap->logattrs);
+                if (dirty || need_write)
+                        if (log->type->flush(log))
+                                bitmap->flags |= BITMAP_WRITE_ERROR;
+                goto out;
+        }
 
         /* look at each page to see if there are any set bits that need to be
          * flushed out to disk */
@@ -883,6 +908,7 @@ void bitmap_unplug(struct bitmap *bitmap)
                 else
                         md_super_wait(bitmap->mddev);
         }
+out:
         if (bitmap->flags & BITMAP_WRITE_ERROR)
                 bitmap_file_kick(bitmap);
 }
@@ -925,11 +951,11 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
                 printk(KERN_INFO "%s: bitmap file is out of date, doing full "
                         "recovery\n", bmname(bitmap));
 
-        bytes = (chunks + 7) / 8;
+        bytes = DIV_ROUND_UP(bitmap->chunks, 8);
         if (!bitmap->mddev->bitmap_info.external)
                 bytes += sizeof(bitmap_super_t);
 
-        num_pages = (bytes + PAGE_SIZE - 1) / PAGE_SIZE;
+        num_pages = DIV_ROUND_UP(bytes, PAGE_SIZE);
 
         if (file && i_size_read(file->f_mapping->host) < bytes) {
                 printk(KERN_INFO "%s: bitmap file too short %lu < %lu\n",
@@ -1090,6 +1116,7 @@ void bitmap_daemon_work(mddev_t *mddev)
         struct page *page = NULL, *lastpage = NULL;
         int blocks;
         void *paddr;
+        struct dm_dirty_log *log = mddev->bitmap_info.log;
 
         /* Use a mutex to guard daemon_work against
          * bitmap_destroy.
@@ -1114,11 +1141,12 @@ void bitmap_daemon_work(mddev_t *mddev)
         spin_lock_irqsave(&bitmap->lock, flags);
         for (j = 0; j < bitmap->chunks; j++) {
                 bitmap_counter_t *bmc;
-                if (!bitmap->filemap)
-                        /* error or shutdown */
-                        break;
-
-                page = filemap_get_page(bitmap, j);
+                if (!bitmap->filemap) {
+                        if (!log)
+                                /* error or shutdown */
+                                break;
+                } else
+                        page = filemap_get_page(bitmap, j);
 
                 if (page != lastpage) {
                         /* skip this page unless it's marked as needing cleaning */
@@ -1187,14 +1215,17 @@ void bitmap_daemon_work(mddev_t *mddev)
                                                   -1);
 
                                 /* clear the bit */
-                                paddr = kmap_atomic(page, KM_USER0);
-                                if (bitmap->flags & BITMAP_HOSTENDIAN)
-                                        clear_bit(file_page_offset(bitmap, j),
-                                                  paddr);
-                                else
-                                        ext2_clear_bit(file_page_offset(bitmap, j),
-                                                       paddr);
-                                kunmap_atomic(paddr, KM_USER0);
+                                if (page) {
+                                        paddr = kmap_atomic(page, KM_USER0);
+                                        if (bitmap->flags & BITMAP_HOSTENDIAN)
+                                                clear_bit(file_page_offset(bitmap, j),
+                                                          paddr);
+                                        else
+                                                ext2_clear_bit(file_page_offset(bitmap, j),
+                                                               paddr);
+                                        kunmap_atomic(paddr, KM_USER0);
+                                } else
+                                        log->type->clear_region(log, j);
                         }
                 } else
                         j |= PAGE_COUNTER_MASK;
@@ -1202,12 +1233,16 @@ void bitmap_daemon_work(mddev_t *mddev)
         spin_unlock_irqrestore(&bitmap->lock, flags);
 
         /* now sync the final page */
-        if (lastpage != NULL) {
+        if (lastpage != NULL || log != NULL) {
                 spin_lock_irqsave(&bitmap->lock, flags);
                 if (test_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE)) {
                         clear_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
                         spin_unlock_irqrestore(&bitmap->lock, flags);
-                        write_page(bitmap, lastpage, 0);
+                        if (lastpage)
+                                write_page(bitmap, lastpage, 0);
+                        else
+                                if (log->type->flush(log))
+                                        bitmap->flags |= BITMAP_WRITE_ERROR;
                 } else {
                         set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
                         spin_unlock_irqrestore(&bitmap->lock, flags);
@@ -1372,7 +1407,9 @@ void bitmap_endwrite(struct bitmap *bitmap, sector_t offset, unsigned long secto
                 (*bmc)--;
                 if (*bmc <= 2)
                         set_page_attr(bitmap,
-                                      filemap_get_page(bitmap, offset >> CHUNK_BLOCK_SHIFT(bitmap)),
+                                      filemap_get_page(
+                                              bitmap,
+                                              offset >> CHUNK_BLOCK_SHIFT(bitmap)),
                                       BITMAP_PAGE_CLEAN);
 
                 spin_unlock_irqrestore(&bitmap->lock, flags);
@@ -1649,10 +1686,13 @@ int bitmap_create(mddev_t *mddev)
 
         BUILD_BUG_ON(sizeof(bitmap_super_t) != 256);
 
-        if (!file && !mddev->bitmap_info.offset) /* bitmap disabled, nothing to do */
+        if (!file
+            && !mddev->bitmap_info.offset
+            && !mddev->bitmap_info.log) /* bitmap disabled, nothing to do */
                 return 0;
 
         BUG_ON(file && mddev->bitmap_info.offset);
+        BUG_ON(mddev->bitmap_info.offset && mddev->bitmap_info.log);
 
         bitmap = kzalloc(sizeof(*bitmap), GFP_KERNEL);
         if (!bitmap)
@@ -1730,7 +1770,17 @@ int bitmap_create(mddev_t *mddev)
             || bitmap->events_cleared == mddev->events)
                 /* no need to keep dirty bits to optimise a re-add of a missing device */
                 start = mddev->recovery_cp;
-        err = bitmap_init_from_disk(bitmap, start);
+        if (mddev->bitmap_info.log) {
+                unsigned long i;
+                struct dm_dirty_log *log = mddev->bitmap_info.log;
+                for (i = 0; i < bitmap->chunks; i++)
+                        if (!log->type->in_sync(log, i, 1))
+                                bitmap_set_memory_bits(bitmap,
+                                                       (sector_t)i << CHUNK_BLOCK_SHIFT(bitmap),
+                                                       1);
+                err = 0;
+        } else
+                err = bitmap_init_from_disk(bitmap, start);
 
         if (err)
                 goto error;
diff --git a/drivers/md/bitmap.h b/drivers/md/bitmap.h
index 3797dea4723a..a7a11134268d 100644
--- a/drivers/md/bitmap.h
+++ b/drivers/md/bitmap.h
@@ -222,6 +222,10 @@ struct bitmap {
         unsigned long file_pages; /* number of pages in the file */
         int last_page_size; /* bytes in the last page */
 
+        unsigned long logattrs; /* used when filemap_attr doesn't exist
+                                 * because we are working with a dirty_log
+                                 */
+
         unsigned long flags;
 
         int allclean;
@@ -243,6 +247,7 @@ struct bitmap {
         wait_queue_head_t behind_wait;
 
         struct sysfs_dirent *sysfs_can_clear;
+
 };
 
 /* the bitmap API */
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 0a850780b5d1..cccbadb31bae 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -317,6 +317,11 @@ struct mddev_s
                                                          * hot-adding a bitmap.  It should
                                                          * eventually be settable by sysfs.
                                                          */
+                /* When md is serving under dm, it might use a
+                 * dirty_log to store the bits.
+                 */
+                struct dm_dirty_log *log;
+
                 struct mutex            mutex;
                 unsigned long           chunksize;
                 unsigned long           daemon_sleep; /* how many jiffies between updates? */