md: Support write-intent bitmaps with externally managed metadata.
In this case, the metadata needs to not be in the same sector as the bitmap. md will not read/write any bitmap metadata. Config must be done via sysfs and when a recovery makes the array non-degraded again, writing 'true' to 'bitmap/can_clear' will allow bits in the bitmap to be cleared again. Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
NeilBrown
parent
624ce4f565
commit
ece5cff0da
4 changed files with 137 additions and 33 deletions
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@ -322,6 +322,22 @@ All md devices contain:
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'backlog' sets a limit on the number of concurrent background
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writes. If there are more than this, new writes will by
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synchronous.
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bitmap/metadata
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This can be either 'internal' or 'external'.
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'internal' is the default and means the metadata for the bitmap
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is stored in the first 256 bytes of the allocated space and is
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managed by the md module.
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'external' means that bitmap metadata is managed externally to
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the kernel (i.e. by some userspace program)
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bitmap/can_clear
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This is either 'true' or 'false'. If 'true', then bits in the
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bitmap will be cleared when the corresponding blocks are thought
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to be in-sync. If 'false', bits will never be cleared.
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This is automatically set to 'false' if a write happens on a
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degraded array, or if the array becomes degraded during a write.
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When metadata is managed externally, it should be set to true
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once the array becomes non-degraded, and this fact has been
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recorded in the metadata.
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@ -497,6 +497,8 @@ void bitmap_update_sb(struct bitmap *bitmap)
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if (!bitmap || !bitmap->mddev) /* no bitmap for this array */
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return;
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if (bitmap->mddev->bitmap_info.external)
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return;
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spin_lock_irqsave(&bitmap->lock, flags);
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if (!bitmap->sb_page) { /* no superblock */
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spin_unlock_irqrestore(&bitmap->lock, flags);
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@ -676,16 +678,26 @@ static int bitmap_mask_state(struct bitmap *bitmap, enum bitmap_state bits,
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* general bitmap file operations
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*/
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/*
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* on-disk bitmap:
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*
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* Use one bit per "chunk" (block set). We do the disk I/O on the bitmap
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* file a page at a time. There's a superblock at the start of the file.
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*/
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/* calculate the index of the page that contains this bit */
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static inline unsigned long file_page_index(unsigned long chunk)
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static inline unsigned long file_page_index(struct bitmap *bitmap, unsigned long chunk)
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{
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return CHUNK_BIT_OFFSET(chunk) >> PAGE_BIT_SHIFT;
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if (!bitmap->mddev->bitmap_info.external)
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chunk += sizeof(bitmap_super_t) << 3;
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return chunk >> PAGE_BIT_SHIFT;
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}
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/* calculate the (bit) offset of this bit within a page */
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static inline unsigned long file_page_offset(unsigned long chunk)
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static inline unsigned long file_page_offset(struct bitmap *bitmap, unsigned long chunk)
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{
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return CHUNK_BIT_OFFSET(chunk) & (PAGE_BITS - 1);
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if (!bitmap->mddev->bitmap_info.external)
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chunk += sizeof(bitmap_super_t) << 3;
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return chunk & (PAGE_BITS - 1);
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}
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/*
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@ -698,8 +710,9 @@ static inline unsigned long file_page_offset(unsigned long chunk)
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static inline struct page *filemap_get_page(struct bitmap *bitmap,
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unsigned long chunk)
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{
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if (file_page_index(chunk) >= bitmap->file_pages) return NULL;
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return bitmap->filemap[file_page_index(chunk) - file_page_index(0)];
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if (file_page_index(bitmap, chunk) >= bitmap->file_pages) return NULL;
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return bitmap->filemap[file_page_index(bitmap, chunk)
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- file_page_index(bitmap, 0)];
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}
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@ -722,7 +735,7 @@ static void bitmap_file_unmap(struct bitmap *bitmap)
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spin_unlock_irqrestore(&bitmap->lock, flags);
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while (pages--)
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if (map[pages]->index != 0) /* 0 is sb_page, release it below */
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if (map[pages] != sb_page) /* 0 is sb_page, release it below */
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free_buffers(map[pages]);
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kfree(map);
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kfree(attr);
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@ -833,7 +846,7 @@ static void bitmap_file_set_bit(struct bitmap *bitmap, sector_t block)
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page = filemap_get_page(bitmap, chunk);
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if (!page) return;
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bit = file_page_offset(chunk);
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bit = file_page_offset(bitmap, chunk);
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/* set the bit */
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kaddr = kmap_atomic(page, KM_USER0);
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@ -931,14 +944,17 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
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"recovery\n", bmname(bitmap));
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bytes = (chunks + 7) / 8;
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if (!bitmap->mddev->bitmap_info.external)
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bytes += sizeof(bitmap_super_t);
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num_pages = (bytes + sizeof(bitmap_super_t) + PAGE_SIZE - 1) / PAGE_SIZE;
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if (file && i_size_read(file->f_mapping->host) < bytes + sizeof(bitmap_super_t)) {
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num_pages = (bytes + PAGE_SIZE - 1) / PAGE_SIZE;
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if (file && i_size_read(file->f_mapping->host) < bytes) {
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printk(KERN_INFO "%s: bitmap file too short %lu < %lu\n",
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bmname(bitmap),
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(unsigned long) i_size_read(file->f_mapping->host),
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bytes + sizeof(bitmap_super_t));
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bytes);
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goto err;
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}
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@ -959,17 +975,16 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
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for (i = 0; i < chunks; i++) {
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int b;
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index = file_page_index(i);
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bit = file_page_offset(i);
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index = file_page_index(bitmap, i);
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bit = file_page_offset(bitmap, i);
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if (index != oldindex) { /* this is a new page, read it in */
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int count;
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/* unmap the old page, we're done with it */
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if (index == num_pages-1)
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count = bytes + sizeof(bitmap_super_t)
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- index * PAGE_SIZE;
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count = bytes - index * PAGE_SIZE;
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else
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count = PAGE_SIZE;
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if (index == 0) {
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if (index == 0 && bitmap->sb_page) {
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/*
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* if we're here then the superblock page
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* contains some bits (PAGE_SIZE != sizeof sb)
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@ -1164,7 +1179,8 @@ void bitmap_daemon_work(mddev_t *mddev)
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/* We are possibly going to clear some bits, so make
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* sure that events_cleared is up-to-date.
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*/
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if (bitmap->need_sync) {
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if (bitmap->need_sync &&
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bitmap->mddev->bitmap_info.external == 0) {
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bitmap_super_t *sb;
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bitmap->need_sync = 0;
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sb = kmap_atomic(bitmap->sb_page, KM_USER0);
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@ -1174,6 +1190,7 @@ void bitmap_daemon_work(mddev_t *mddev)
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write_page(bitmap, bitmap->sb_page, 1);
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}
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spin_lock_irqsave(&bitmap->lock, flags);
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if (!bitmap->need_sync)
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clear_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
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}
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bmc = bitmap_get_counter(bitmap,
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@ -1189,7 +1206,7 @@ void bitmap_daemon_work(mddev_t *mddev)
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if (*bmc == 2) {
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*bmc=1; /* maybe clear the bit next time */
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set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
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} else if (*bmc == 1) {
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} else if (*bmc == 1 && !bitmap->need_sync) {
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/* we can clear the bit */
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*bmc = 0;
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bitmap_count_page(bitmap,
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@ -1199,9 +1216,11 @@ void bitmap_daemon_work(mddev_t *mddev)
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/* clear the bit */
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paddr = kmap_atomic(page, KM_USER0);
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if (bitmap->flags & BITMAP_HOSTENDIAN)
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clear_bit(file_page_offset(j), paddr);
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clear_bit(file_page_offset(bitmap, j),
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paddr);
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else
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ext2_clear_bit(file_page_offset(j), paddr);
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ext2_clear_bit(file_page_offset(bitmap, j),
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paddr);
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kunmap_atomic(paddr, KM_USER0);
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}
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} else
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@ -1356,6 +1375,7 @@ void bitmap_endwrite(struct bitmap *bitmap, sector_t offset, unsigned long secto
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bitmap->events_cleared < bitmap->mddev->events) {
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bitmap->events_cleared = bitmap->mddev->events;
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bitmap->need_sync = 1;
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sysfs_notify_dirent(bitmap->sysfs_can_clear);
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}
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if (!success && ! (*bmc & NEEDED_MASK))
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@ -1613,6 +1633,9 @@ void bitmap_destroy(mddev_t *mddev)
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if (mddev->thread)
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mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
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if (bitmap->sysfs_can_clear)
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sysfs_put(bitmap->sysfs_can_clear);
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bitmap_free(bitmap);
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}
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@ -1629,6 +1652,7 @@ int bitmap_create(mddev_t *mddev)
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struct file *file = mddev->bitmap_info.file;
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int err;
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sector_t start;
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struct sysfs_dirent *bm;
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BUILD_BUG_ON(sizeof(bitmap_super_t) != 256);
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@ -1648,6 +1672,13 @@ int bitmap_create(mddev_t *mddev)
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bitmap->mddev = mddev;
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bm = sysfs_get_dirent(mddev->kobj.sd, "bitmap");
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if (bm) {
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bitmap->sysfs_can_clear = sysfs_get_dirent(bm, "can_clear");
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sysfs_put(bm);
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} else
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bitmap->sysfs_can_clear = NULL;
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bitmap->file = file;
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if (file) {
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get_file(file);
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@ -1658,7 +1689,16 @@ int bitmap_create(mddev_t *mddev)
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vfs_fsync(file, file->f_dentry, 1);
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}
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/* read superblock from bitmap file (this sets mddev->bitmap_info.chunksize) */
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if (!mddev->bitmap_info.external)
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err = bitmap_read_sb(bitmap);
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else {
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err = 0;
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if (mddev->bitmap_info.chunksize == 0 ||
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mddev->bitmap_info.daemon_sleep == 0)
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/* chunksize and time_base need to be
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* set first. */
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err = -EINVAL;
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}
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if (err)
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goto error;
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@ -1777,7 +1817,8 @@ location_store(mddev_t *mddev, const char *buf, size_t len)
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return rv;
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if (offset == 0)
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return -EINVAL;
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if (mddev->major_version == 0 &&
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if (mddev->bitmap_info.external == 0 &&
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mddev->major_version == 0 &&
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offset != mddev->bitmap_info.default_offset)
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return -EINVAL;
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mddev->bitmap_info.offset = offset;
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@ -1906,11 +1947,66 @@ chunksize_store(mddev_t *mddev, const char *buf, size_t len)
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static struct md_sysfs_entry bitmap_chunksize =
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__ATTR(chunksize, S_IRUGO|S_IWUSR, chunksize_show, chunksize_store);
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static ssize_t metadata_show(mddev_t *mddev, char *page)
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{
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return sprintf(page, "%s\n", (mddev->bitmap_info.external
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? "external" : "internal"));
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}
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static ssize_t metadata_store(mddev_t *mddev, const char *buf, size_t len)
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{
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if (mddev->bitmap ||
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mddev->bitmap_info.file ||
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mddev->bitmap_info.offset)
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return -EBUSY;
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if (strncmp(buf, "external", 8) == 0)
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mddev->bitmap_info.external = 1;
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else if (strncmp(buf, "internal", 8) == 0)
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mddev->bitmap_info.external = 0;
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else
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return -EINVAL;
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return len;
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}
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static struct md_sysfs_entry bitmap_metadata =
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__ATTR(metadata, S_IRUGO|S_IWUSR, metadata_show, metadata_store);
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static ssize_t can_clear_show(mddev_t *mddev, char *page)
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{
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int len;
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if (mddev->bitmap)
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len = sprintf(page, "%s\n", (mddev->bitmap->need_sync ?
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"false" : "true"));
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else
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len = sprintf(page, "\n");
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return len;
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}
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static ssize_t can_clear_store(mddev_t *mddev, const char *buf, size_t len)
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{
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if (mddev->bitmap == NULL)
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return -ENOENT;
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if (strncmp(buf, "false", 5) == 0)
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mddev->bitmap->need_sync = 1;
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else if (strncmp(buf, "true", 4) == 0) {
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if (mddev->degraded)
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return -EBUSY;
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mddev->bitmap->need_sync = 0;
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} else
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return -EINVAL;
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return len;
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}
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static struct md_sysfs_entry bitmap_can_clear =
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__ATTR(can_clear, S_IRUGO|S_IWUSR, can_clear_show, can_clear_store);
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static struct attribute *md_bitmap_attrs[] = {
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&bitmap_location.attr,
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&bitmap_timeout.attr,
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&bitmap_backlog.attr,
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&bitmap_chunksize.attr,
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&bitmap_metadata.attr,
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&bitmap_can_clear.attr,
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NULL
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};
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struct attribute_group md_bitmap_group = {
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@ -118,16 +118,6 @@ typedef __u16 bitmap_counter_t;
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(CHUNK_BLOCK_SHIFT(bitmap) + PAGE_COUNTER_SHIFT - 1)
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#define PAGEPTR_BLOCK_MASK(bitmap) (PAGEPTR_BLOCK_RATIO(bitmap) - 1)
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/*
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* on-disk bitmap:
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*
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* Use one bit per "chunk" (block set). We do the disk I/O on the bitmap
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* file a page at a time. There's a superblock at the start of the file.
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*/
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/* map chunks (bits) to file pages - offset by the size of the superblock */
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#define CHUNK_BIT_OFFSET(chunk) ((chunk) + (sizeof(bitmap_super_t) << 3))
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#endif
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/*
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@ -250,6 +240,7 @@ struct bitmap {
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wait_queue_head_t write_wait;
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wait_queue_head_t overflow_wait;
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struct sysfs_dirent *sysfs_can_clear;
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};
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/* the bitmap API */
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@ -296,6 +296,7 @@ struct mddev_s
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unsigned long chunksize;
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unsigned long daemon_sleep; /* how many seconds between updates? */
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unsigned long max_write_behind; /* write-behind mode */
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int external;
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} bitmap_info;
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struct list_head all_mddevs;
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