[PATCH v5 0/4] device_list_add() peparation to add reappearing missing device

[PATCH v5 0/4] device_list_add() peparation to add reappearing missing device

[Anand Jain]

(Apply on top of my patchset
   [PATCH v4 0/6] preparatory work to add device forget
 for conflict free apply. They don't actually depend on
 each other though).

v4->v5:
 @3/4: Fix null pointer dereference of device pointer in fn
 btrfs_scan_one_device() when device_list_add() fails.

v3->v4:
 @3/4: Just return device instead of PTR_ERR(ERR_PTR(device));

v2->v3:
 Fix device_list_add() fn description which was still referring to the
 previous return values.

v1->v2:
 Drop patch 5/5 for uuid_mutex optimize. That was wrong. Thanks Josef.
 In patch 3/5 make btrfs_device * as return.

Cleanup of device_list_add(), mainly in preparation to handle
reappearing missing device which its next reroll will be sent
separately.


*** BLURB HERE ***

Anand Jain (4):
  btrfs: move pr_info into device_list_add
  btrfs: set the total_devices in device_list_add()
  btrfs: get device pointer from device_list_add()
  btrfs: drop devid as device_list_add() arg

 fs/btrfs/volumes.c | 65 +++++++++++++++++++++++-------------------------------
 1 file changed, 28 insertions(+), 37 deletions(-)

-- 
2.7.0

[PATCH 1/4] btrfs: move pr_info into device_list_add

[Anand Jain]

Commit 60999ca4b403 ("btrfs: make device scan less noisy")
adds return value 1 to device_list_add(), so that parent function can
call pr_info only when new device is added. Move the pr_info() part
into device_list_add() so that this function can be kept simple.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
---
 fs/btrfs/volumes.c | 29 +++++++++++------------------
 1 file changed, 11 insertions(+), 18 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 9e743d289dfd..3a272ae7f32d 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -729,8 +729,7 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
  * Add new device to list of registered devices
  *
  * Returns:
- * 1   - first time device is seen
- * 0   - device already known
+ * 0   - device already known or newly added
  * < 0 - error
  */
 static noinline int device_list_add(const char *path,
@@ -740,7 +739,6 @@ static noinline int device_list_add(const char *path,
 	struct btrfs_device *device;
 	struct btrfs_fs_devices *fs_devices;
 	struct rcu_string *name;
-	int ret = 0;
 	u64 found_transid = btrfs_super_generation(disk_super);
 
 	fs_devices = find_fsid(disk_super->fsid);
@@ -780,9 +778,16 @@ static noinline int device_list_add(const char *path,
 		fs_devices->num_devices++;
 		mutex_unlock(&fs_devices->device_list_mutex);
 
-		ret = 1;
 		device->fs_devices = fs_devices;
 		btrfs_free_stale_devices(path, device);
+
+		if (disk_super->label[0])
+			pr_info("BTRFS: device label %s devid %llu transid %llu %s\n",
+				disk_super->label, devid, found_transid, path);
+		else
+			pr_info("BTRFS: device fsid %pU devid %llu transid %llu %s\n",
+				disk_super->fsid, devid, found_transid, path);
+
 	} else if (!device->name || strcmp(device->name->str, path)) {
 		/*
 		 * When FS is already mounted.
@@ -843,7 +848,7 @@ static noinline int device_list_add(const char *path,
 
 	*fs_devices_ret = fs_devices;
 
-	return ret;
+	return 0;
 }
 
 static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig)
@@ -1182,7 +1187,6 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
 	struct page *page;
 	int ret;
 	u64 devid;
-	u64 transid;
 	u64 total_devices;
 	u64 bytenr;
 
@@ -1205,25 +1209,14 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
 	}
 
 	devid = btrfs_stack_device_id(&disk_super->dev_item);
-	transid = btrfs_super_generation(disk_super);
 	total_devices = btrfs_super_num_devices(disk_super);
 
 	mutex_lock(&uuid_mutex);
 	ret = device_list_add(path, disk_super, devid, fs_devices_ret);
-	if (ret >= 0 && fs_devices_ret)
+	if (!ret && fs_devices_ret)
 		(*fs_devices_ret)->total_devices = total_devices;
 	mutex_unlock(&uuid_mutex);
 
-	if (ret > 0) {
-		if (disk_super->label[0])
-			pr_info("BTRFS: device label %s ", disk_super->label);
-		else
-			pr_info("BTRFS: device fsid %pU ", disk_super->fsid);
-
-		pr_cont("devid %llu transid %llu %s\n", devid, transid, path);
-		ret = 0;
-	}
-
 	btrfs_release_disk_super(page);
 
 error_bdev_put:
-- 
2.7.0

[PATCH 2/4] btrfs: set the total_devices in device_list_add()

[Anand Jain]

There is no other parent for device_list_add() except for
btrfs_scan_one_device(), which would set btrfs_fs_devices::total_devices
if device_list_add is successful and this can be done with in
device_list_add() itself.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
---
 fs/btrfs/volumes.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 3a272ae7f32d..4a4298017fe1 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -846,6 +846,8 @@ static noinline int device_list_add(const char *path,
 	if (!fs_devices->opened)
 		device->generation = found_transid;
 
+	fs_devices->total_devices = btrfs_super_num_devices(disk_super);
+
 	*fs_devices_ret = fs_devices;
 
 	return 0;
@@ -1187,7 +1189,6 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
 	struct page *page;
 	int ret;
 	u64 devid;
-	u64 total_devices;
 	u64 bytenr;
 
 	/*
@@ -1209,12 +1210,9 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
 	}
 
 	devid = btrfs_stack_device_id(&disk_super->dev_item);
-	total_devices = btrfs_super_num_devices(disk_super);
 
 	mutex_lock(&uuid_mutex);
 	ret = device_list_add(path, disk_super, devid, fs_devices_ret);
-	if (!ret && fs_devices_ret)
-		(*fs_devices_ret)->total_devices = total_devices;
 	mutex_unlock(&uuid_mutex);
 
 	btrfs_release_disk_super(page);
-- 
2.7.0

[PATCH 3/4] btrfs: get device pointer from device_list_add()

[Anand Jain]

Instead of pointer to btrfs_fs_devices as an arg in device_list_add()
better to get pointer to btrfs_device as return value, then we have
both, pointer to btrfs_device and btrfs_fs_devices. btrfs_device is
needed to handle reappearing missing device.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/volumes.c | 34 ++++++++++++++++++----------------
 1 file changed, 18 insertions(+), 16 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 4a4298017fe1..a86c3a14ec89 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -729,12 +729,11 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
  * Add new device to list of registered devices
  *
  * Returns:
- * 0   - device already known or newly added
- * < 0 - error
+ * device pointer which was just added or updated when successful
+ * error pointer when failed
  */
-static noinline int device_list_add(const char *path,
-			   struct btrfs_super_block *disk_super,
-			   u64 devid, struct btrfs_fs_devices **fs_devices_ret)
+static noinline struct btrfs_device *device_list_add(const char *path,
+			   struct btrfs_super_block *disk_super, u64 devid)
 {
 	struct btrfs_device *device;
 	struct btrfs_fs_devices *fs_devices;
@@ -745,7 +744,7 @@ static noinline int device_list_add(const char *path,
 	if (!fs_devices) {
 		fs_devices = alloc_fs_devices(disk_super->fsid);
 		if (IS_ERR(fs_devices))
-			return PTR_ERR(fs_devices);
+			return ERR_PTR(PTR_ERR(fs_devices));
 
 		list_add(&fs_devices->list, &fs_uuids);
 
@@ -757,19 +756,19 @@ static noinline int device_list_add(const char *path,
 
 	if (!device) {
 		if (fs_devices->opened)
-			return -EBUSY;
+			return ERR_PTR(-EBUSY);
 
 		device = btrfs_alloc_device(NULL, &devid,
 					    disk_super->dev_item.uuid);
 		if (IS_ERR(device)) {
 			/* we can safely leave the fs_devices entry around */
-			return PTR_ERR(device);
+			return device;
 		}
 
 		name = rcu_string_strdup(path, GFP_NOFS);
 		if (!name) {
 			free_device(device);
-			return -ENOMEM;
+			return ERR_PTR(-ENOMEM);
 		}
 		rcu_assign_pointer(device->name, name);
 
@@ -823,12 +822,12 @@ static noinline int device_list_add(const char *path,
 			 * with larger generation number or the last-in if
 			 * generation are equal.
 			 */
-			return -EEXIST;
+			return ERR_PTR(-EEXIST);
 		}
 
 		name = rcu_string_strdup(path, GFP_NOFS);
 		if (!name)
-			return -ENOMEM;
+			return ERR_PTR(-ENOMEM);
 		rcu_string_free(device->name);
 		rcu_assign_pointer(device->name, name);
 		if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state)) {
@@ -848,9 +847,7 @@ static noinline int device_list_add(const char *path,
 
 	fs_devices->total_devices = btrfs_super_num_devices(disk_super);
 
-	*fs_devices_ret = fs_devices;
-
-	return 0;
+	return device;
 }
 
 static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig)
@@ -1185,9 +1182,10 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
 			  struct btrfs_fs_devices **fs_devices_ret)
 {
 	struct btrfs_super_block *disk_super;
+	struct btrfs_device *device;
 	struct block_device *bdev;
 	struct page *page;
-	int ret;
+	int ret = 0;
 	u64 devid;
 	u64 bytenr;
 
@@ -1212,8 +1210,12 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
 	devid = btrfs_stack_device_id(&disk_super->dev_item);
 
 	mutex_lock(&uuid_mutex);
-	ret = device_list_add(path, disk_super, devid, fs_devices_ret);
+	device = device_list_add(path, disk_super, devid);
 	mutex_unlock(&uuid_mutex);
+	if (IS_ERR(device))
+		ret = PTR_ERR(device);
+	else
+		*fs_devices_ret = device->fs_devices;
 
 	btrfs_release_disk_super(page);
 
-- 
2.7.0

[PATCH 4/4] btrfs: drop devid as device_list_add() arg

[Anand Jain]

As struct btrfs_disk_super is being passed, so it can get devid
the same way its parent does.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
---
 fs/btrfs/volumes.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index a86c3a14ec89..03f2685a5018 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -733,12 +733,13 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
  * error pointer when failed
  */
 static noinline struct btrfs_device *device_list_add(const char *path,
-			   struct btrfs_super_block *disk_super, u64 devid)
+			   struct btrfs_super_block *disk_super)
 {
 	struct btrfs_device *device;
 	struct btrfs_fs_devices *fs_devices;
 	struct rcu_string *name;
 	u64 found_transid = btrfs_super_generation(disk_super);
+	u64 devid = btrfs_stack_device_id(&disk_super->dev_item);
 
 	fs_devices = find_fsid(disk_super->fsid);
 	if (!fs_devices) {
@@ -1186,7 +1187,6 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
 	struct block_device *bdev;
 	struct page *page;
 	int ret = 0;
-	u64 devid;
 	u64 bytenr;
 
 	/*
@@ -1207,10 +1207,8 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
 		goto error_bdev_put;
 	}
 
-	devid = btrfs_stack_device_id(&disk_super->dev_item);
-
 	mutex_lock(&uuid_mutex);
-	device = device_list_add(path, disk_super, devid);
+	device = device_list_add(path, disk_super);
 	mutex_unlock(&uuid_mutex);
 	if (IS_ERR(device))
 		ret = PTR_ERR(device);
-- 
2.7.0