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>

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 29a3c86..9376526 100644 (file)
--- 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 3797dea..a7a1113 100644 (file)
--- 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 0a85078..cccbadb 100644 (file)
--- 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? */