On 05/04/2016 01:31 AM, David Sterba wrote:
On Thu, Apr 14, 2016 at 06:24:10PM +0800, Anand Jain wrote:
Yauhen reported in the ML that s_bdev is null at mount, and
s_bdev gets updated to some device when missing device is
replaced, as because bdev is null for missing device, things
gets matched up. Fix this by checking if s_bdev is set. I
didn't want to completely remove updating s_bdev because
the future multi device support at vfs layer may need it.
Signed-off-by: Anand Jain <anand.j...@oracle.com>
Reported-by: Yauhen Kharuzhy <yauhen.kharu...@zavadatar.com>
Do you have a testcase for that?
For this particular bug/fix no. As I went through the vfs
layer to understand the s_bdev usage. It appears that s_bdev
is used for fsync.
But btrfs kept s_bdev NULL, which will make vfs layer to fail
safe in that context.
We need to continue to keep s_bdev null, even after the
replace missing. The bug is that it didn't. As shown below.
mkfs.btrfs -f -draid1 -mraid1 /dev/sdc /dev/sdd /dev/sde
modprobe -r btrfs && modprobe btrfs
mount -o degraded,device=/dev/sdc /dev/sde /btrfs
-----
cat /proc/fs/btrfs/fsinfo [1]
[fsid: 60ca666b-83e8-4a28-a0cb-9b7ddb0451e2]
sb->s_bdev: null
latest_bdev: sde
-----
btrfs repl start 2 /dev/sdf /btrfs -f
-----
cat /proc/fs/btrfs/fsinfo
[fsid: 60ca666b-83e8-4a28-a0cb-9b7ddb0451e2]
sb->s_bdev: sdf
latest_bdev: sde
-----
As there are more patches touching the
device pointers I'd rather see some test coverage. Thanks.
Hm, yes the btrfs-vm test coverage needs a review at xfstests.
Let me try.
For my quick verifications, I have been using..
https://github.com/asj/exercise-btrfs-volume-mgt.git
has around quick 30+ btrfs-vm related tests. But very raw.
Omar added test case 027 to test replace missing. The for-next
plus 3 patches[2] passes 027 as well.
Do you have any particular test coverage idea in mind ?
Thanks, Anand
[1]
For /proc/fs/btrfs/fsinfo see attached which should be applied
on top of the patch.
[PATCH] btrfs: procfs: devlist: introduce /proc/fs/btrfs/devlist
[2]
86eb5d598d58 btrfs: cleanup assigning next active device with a check
7b09eb01d80c btrfs: s_bdev is not null after missing replace
6237a895bc31 btrfs: fix lock dep warning move scratch super outside of
chunk_mutex
>From 0411476bdf720556945457f63032aca8b3f5390e Mon Sep 17 00:00:00 2001
From: Anand Jain <anand.j...@oracle.com>
Date: Thu, 14 Apr 2016 11:28:41 +0800
Subject: [PATCH 2/2] btrfs: procfs: fsinfo: introduce /proc/fs/btrfs/fsinfo
for debugging
Signed-off-by: Anand Jain <anand.j...@oracle.com>
---
fs/btrfs/procfs.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 70 insertions(+), 6 deletions(-)
diff --git a/fs/btrfs/procfs.c b/fs/btrfs/procfs.c
index 99edcad8a825..337ae1212130 100644
--- a/fs/btrfs/procfs.c
+++ b/fs/btrfs/procfs.c
@@ -7,9 +7,48 @@
#define BTRFS_PROC_PATH "fs/btrfs"
#define BTRFS_PROC_DEVLIST "devlist"
+#define BTRFS_PROC_FSINFO "fsinfo"
struct proc_dir_entry *btrfs_proc_root;
+void btrfs_print_fsinfo(struct seq_file *seq)
+{
+
+ /* Btrfs Procfs String Len */
+#define BPSL 256
+#define BTRFS_SEQ_PRINT2(plist, arg)\
+ snprintf(str, BPSL, plist, arg);\
+ seq_printf(seq, str)
+
+ char str[BPSL];
+ char b[BDEVNAME_SIZE];
+ struct list_head *cur_uuid;
+ struct btrfs_fs_info *fs_info;
+ struct btrfs_fs_devices *fs_devices;
+ struct list_head *fs_uuids = btrfs_get_fs_uuids();
+
+ seq_printf(seq, "\n#Its Experimental, parameters may change without notice.\n\n");
+
+ mutex_lock(&uuid_mutex);
+ list_for_each(cur_uuid, fs_uuids) {
+ fs_devices = list_entry(cur_uuid, struct btrfs_fs_devices, list);
+ fs_info = fs_devices->fs_info;
+ if (!fs_info)
+ continue;
+
+ BTRFS_SEQ_PRINT2("[fsid: %pU]\n", fs_devices->fsid);
+ BTRFS_SEQ_PRINT2("\tsb->s_bdev:\t\t%s\n",
+ fs_info->sb->s_bdev ?
+ bdevname(fs_info->sb->s_bdev, b):
+ "null");
+ BTRFS_SEQ_PRINT2("\tlatest_bdev:\t\t%s\n",
+ fs_devices->latest_bdev ?
+ bdevname(fs_devices->latest_bdev, b):
+ "null");
+ }
+ mutex_unlock(&uuid_mutex);
+}
+
void btrfs_print_devlist(struct seq_file *seq)
{
@@ -120,20 +159,40 @@ again_fs_devs:
}
mutex_unlock(&uuid_mutex);
}
+
+static int btrfs_fsinfo_show(struct seq_file *seq, void *offset)
+{
+ btrfs_print_fsinfo(seq);
+ return 0;
+}
+
static int btrfs_devlist_show(struct seq_file *seq, void *offset)
{
btrfs_print_devlist(seq);
return 0;
}
-static int btrfs_seq_open(struct inode *inode, struct file *file)
+static int btrfs_seq_fsinfo_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, btrfs_fsinfo_show, PDE_DATA(inode));
+}
+
+static int btrfs_seq_devlist_open(struct inode *inode, struct file *file)
{
return single_open(file, btrfs_devlist_show, PDE_DATA(inode));
}
-static const struct file_operations btrfs_seq_fops = {
+static const struct file_operations btrfs_seq_devlist_fops = {
.owner = THIS_MODULE,
- .open = btrfs_seq_open,
+ .open = btrfs_seq_devlist_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static const struct file_operations btrfs_seq_fsinfo_fops = {
+ .owner = THIS_MODULE,
+ .open = btrfs_seq_fsinfo_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
@@ -142,16 +201,21 @@ static const struct file_operations btrfs_seq_fops = {
void btrfs_init_procfs(void)
{
btrfs_proc_root = proc_mkdir(BTRFS_PROC_PATH, NULL);
- if (btrfs_proc_root)
+ if (btrfs_proc_root) {
proc_create_data(BTRFS_PROC_DEVLIST, S_IRUGO, btrfs_proc_root,
- &btrfs_seq_fops, NULL);
+ &btrfs_seq_devlist_fops, NULL);
+ proc_create_data(BTRFS_PROC_FSINFO, S_IRUGO, btrfs_proc_root,
+ &btrfs_seq_fsinfo_fops, NULL);
+ }
return;
}
void btrfs_exit_procfs(void)
{
- if (btrfs_proc_root)
+ if (btrfs_proc_root) {
remove_proc_entry(BTRFS_PROC_DEVLIST, btrfs_proc_root);
+ remove_proc_entry(BTRFS_PROC_FSINFO, btrfs_proc_root);
+ }
remove_proc_entry(BTRFS_PROC_PATH, NULL);
}
--
2.7.0
