--- /dev/null
+This patch is no longer needed for Lustre. It is only included
+for testing and ease of using the same kernel with older Lustre
+versions. This testing functionality was replaced in Linux 3.0
+by the dm-flakey driver.
+
+This functionality is mainly used during testing, in order to
+simulate a server crash for ldiskfs by discarding all of the
+writes to the filesystem. For recovery testing we could simulate
+this by using a special loopback or DM device that also discards
+writes to the device.
+
+This functionality is also used by target "failback" in order
+to speed up service shutdown and takeover by the other node
+during controlled operation. However, it would also be possible
+to do this by simply allowing all of the in-flight requests to
+complete and then waiting for the service to stop. This will
+also be needed by the DMU-OSD, because discarding of writes on
+a DMU-based target is not safe as it could trigger a storage
+failure if the data is ever read from disk again and the
+checksum does not match that expected by the block pointer.
+
+Index: linux-4.4.59-1/block/blk-core.c
+===================================================================
+--- linux-4.4.59-1.orig/block/blk-core.c
++++ linux-4.4.59-1/block/blk-core.c
+@@ -1804,6 +1804,8 @@ static inline bool should_fail_request(s
+
+ #endif /* CONFIG_FAIL_MAKE_REQUEST */
+
++int dev_check_rdonly(struct block_device *bdev);
++
+ /*
+ * Check whether this bio extends beyond the end of the device.
+ */
+@@ -1857,6 +1859,12 @@ generic_make_request_checks(struct bio *
+ goto end_io;
+ }
+
++ /* this is cfs's dev_rdonly check */
++ if (bio_data_dir(bio) && dev_check_rdonly(bio->bi_bdev)) {
++ err = 0;
++ goto end_io;
++ }
++
+ part = bio->bi_bdev->bd_part;
+ if (should_fail_request(part, bio->bi_iter.bi_size) ||
+ should_fail_request(&part_to_disk(part)->part0,
+@@ -3454,6 +3462,99 @@ void blk_set_runtime_active(struct reque
+ EXPORT_SYMBOL(blk_set_runtime_active);
+ #endif
+
++/*
++ * Debug code for turning block devices "read-only" (will discard writes
++ * silently). This is for filesystem crash/recovery testing.
++ */
++struct deventry {
++ dev_t dev;
++ struct deventry *next;
++};
++
++static struct deventry *devlist = NULL;
++static spinlock_t devlock = __SPIN_LOCK_UNLOCKED(devlock);
++
++int dev_check_rdonly(struct block_device *bdev)
++{
++ struct deventry *cur;
++
++ if (!bdev)
++ return 0;
++
++ spin_lock(&devlock);
++ cur = devlist;
++ while(cur) {
++ if (bdev->bd_dev == cur->dev) {
++ spin_unlock(&devlock);
++ return 1;
++ }
++ cur = cur->next;
++ }
++ spin_unlock(&devlock);
++ return 0;
++}
++
++void dev_set_rdonly(struct block_device *bdev)
++{
++ struct deventry *newdev, *cur;
++
++ if (!bdev)
++ return;
++
++ newdev = kmalloc(sizeof(struct deventry), GFP_KERNEL);
++ if (!newdev)
++ return;
++
++ spin_lock(&devlock);
++ cur = devlist;
++ while(cur) {
++ if (bdev->bd_dev == cur->dev) {
++ spin_unlock(&devlock);
++ kfree(newdev);
++ return;
++ }
++ cur = cur->next;
++ }
++ newdev->dev = bdev->bd_dev;
++ newdev->next = devlist;
++ devlist = newdev;
++ spin_unlock(&devlock);
++ printk(KERN_WARNING "Turning device %s (%#x) read-only\n",
++ bdev->bd_disk ? bdev->bd_disk->disk_name : "", bdev->bd_dev);
++}
++
++void dev_clear_rdonly(struct block_device *bdev)
++{
++ struct deventry *cur, *last = NULL;
++
++ if (!bdev)
++ return;
++
++ spin_lock(&devlock);
++ cur = devlist;
++ while(cur) {
++ if (bdev->bd_dev == cur->dev) {
++ if (last)
++ last->next = cur->next;
++ else
++ devlist = cur->next;
++ spin_unlock(&devlock);
++ kfree(cur);
++ printk(KERN_WARNING "Removing read-only on %s (%#x)\n",
++ bdev->bd_disk ? bdev->bd_disk->disk_name :
++ "unknown block", bdev->bd_dev);
++ return;
++ }
++ last = cur;
++ cur = cur->next;
++ }
++ spin_unlock(&devlock);
++}
++
++EXPORT_SYMBOL(dev_set_rdonly);
++EXPORT_SYMBOL(dev_clear_rdonly);
++EXPORT_SYMBOL(dev_check_rdonly);
++
+ int __init blk_dev_init(void)
+ {
+ BUILD_BUG_ON(REQ_OP_LAST >= (1 << REQ_OP_BITS));
+Index: linux-4.4.59-1/fs/block_dev.c
+===================================================================
+--- linux-4.4.59-1.orig/fs/block_dev.c
++++ linux-4.4.59-1/fs/block_dev.c
+@@ -1914,6 +1914,7 @@ static void __blkdev_put(struct block_de
+ if (bdev != bdev->bd_contains)
+ victim = bdev->bd_contains;
+ bdev->bd_contains = NULL;
++ dev_clear_rdonly(bdev);
+
+ put_disk(disk);
+ module_put(owner);
+Index: linux-4.4.59-1/include/linux/fs.h
+===================================================================
+--- linux-4.4.59-1.orig/include/linux/fs.h
++++ linux-4.4.59-1/include/linux/fs.h
+@@ -2624,6 +2624,10 @@ extern void inode_sb_list_add(struct ino
+ #ifdef CONFIG_BLOCK
+ extern int bdev_read_only(struct block_device *);
+ #endif
++#define HAVE_CLEAR_RDONLY_ON_PUT
++extern void dev_set_rdonly(struct block_device *bdev);
++extern int dev_check_rdonly(struct block_device *bdev);
++extern void dev_clear_rdonly(struct block_device *bdev);
+ extern int set_blocksize(struct block_device *, int);
+ extern int sb_set_blocksize(struct super_block *, int);
+ extern int sb_min_blocksize(struct super_block *, int);
git://git.whamcloud.com / fs / lustre-release.git / blobdiff