Re: report a bug that panic when grow size for external bitmap

[NeilBrown <neilb@suse.com>]

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On Wed, Aug 30 2017, Zhilong Liu wrote:

>
> Hi, Neil;
>      I have tested the following patch, I still got the call-trace after 
> I built with it.
> If you need other infos, I would append.

Ok, one more try.  If this doesn't work I do the testing myself to
avoid the back-and-forth.

Thanks,
NeilBrown

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 40f3cd7eab0f..05ba9c7d33b4 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -368,12 +368,7 @@ static int read_page(struct file *file, unsigned long index,
 	pr_debug("read bitmap file (%dB @ %llu)\n", (int)PAGE_SIZE,
 		 (unsigned long long)index << PAGE_SHIFT);
 
-	bh = alloc_page_buffers(page, 1<<inode->i_blkbits, 0);
-	if (!bh) {
-		ret = -ENOMEM;
-		goto out;
-	}
-	attach_page_buffers(page, bh);
+	bh = page_buffers(page);
 	block = index << (PAGE_SHIFT - inode->i_blkbits);
 	while (bh) {
 		if (count == 0)
@@ -616,9 +611,16 @@ static int bitmap_read_sb(struct bitmap *bitmap)
 	}
 
 	if (bitmap->storage.file) {
-		loff_t isize = i_size_read(bitmap->storage.file->f_mapping->host);
+		struct inode *inode = bitmap->storage.file->f_mapping->host;
+		loff_t isize = i_size_read(inode);
 		int bytes = isize > PAGE_SIZE ? PAGE_SIZE : isize;
+		struct buffer_head *bh;
 
+		bh = alloc_page_buffers(sb_page, 1 << inode->i_blkbits, 0);
+		if (bh)
+			attach_page_buffers(sb_page, bh);
+		else
+			return -ENOMEM;
 		err = read_page(bitmap->storage.file, 0,
 				bitmap, bytes, sb_page);
 	} else {
@@ -771,12 +773,18 @@ static inline struct page *filemap_get_page(struct bitmap_storage *store,
 }
 
 static int bitmap_storage_alloc(struct bitmap_storage *store,
-				unsigned long chunks, int with_super,
+				unsigned long chunks,
+				struct file *file,
+				int with_super,
 				int slot_number)
 {
 	int pnum, offset = 0;
 	unsigned long num_pages;
 	unsigned long bytes;
+	struct inode *inode = NULL;
+
+	if (file)
+		inode = file_inode(file);
 
 	bytes = DIV_ROUND_UP(chunks, 8);
 	if (with_super)
@@ -801,15 +809,33 @@ static int bitmap_storage_alloc(struct bitmap_storage *store,
 		store->filemap[0] = store->sb_page;
 		pnum = 1;
 		store->sb_page->index = offset;
+		if (inode) {
+			struct buffer_head *bh;
+			struct page *p = store->sb_page;
+			bh = alloc_page_buffers(p, 1 << inode->i_blkbits, 0);
+			if (bh)
+				attach_page_buffers(p, bh);
+			else
+				return -ENOMEM;
+		}
 	}
 
 	for ( ; pnum < num_pages; pnum++) {
-		store->filemap[pnum] = alloc_page(GFP_KERNEL|__GFP_ZERO);
-		if (!store->filemap[pnum]) {
+		struct page *p = alloc_page(GFP_KERNEL|__GFP_ZERO);
+		store->filemap[pnum] = p;
+		if (!p) {
 			store->file_pages = pnum;
 			return -ENOMEM;
 		}
-		store->filemap[pnum]->index = pnum + offset;
+		if (inode) {
+			struct buffer_head *bh;
+			bh = alloc_page_buffers(p, 1 << inode->i_blkbits, 0);
+			if (bh)
+				attach_page_buffers(p, bh);
+			else
+				return -ENOMEM;
+		}
+		p->index = pnum + offset;
 	}
 	store->file_pages = pnum;
 
@@ -2091,7 +2117,7 @@ int bitmap_resize(struct bitmap *bitmap, sector_t blocks,
 	chunks = DIV_ROUND_UP_SECTOR_T(blocks, 1 << chunkshift);
 	memset(&store, 0, sizeof(store));
 	if (bitmap->mddev->bitmap_info.offset || bitmap->mddev->bitmap_info.file)
-		ret = bitmap_storage_alloc(&store, chunks,
+		ret = bitmap_storage_alloc(&store, chunks, bitmap->mddev->bitmap_info.file,
 					   !bitmap->mddev->bitmap_info.external,
 					   mddev_is_clustered(bitmap->mddev)
 					   ? bitmap->cluster_slot : 0);

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