nilfs2: integrate sysfs support into driver
This patch integrates creation of sysfs groups and
attributes into NILFS file system driver.
It was found the issue with nilfs_sysfs_{create/delete}_snapshot_group
functions by Michael L Semon <mlsemon35@gmail.com> in the first
version of the patch:
BUG: sleeping function called from invalid context at kernel/locking/mutex.c:579
in_atomic(): 1, irqs_disabled(): 0, pid: 32676, name: umount.nilfs2
2 locks held by umount.nilfs2/32676:
#0: (&type->s_umount_key#21){++++..}, at: [<790c18e2>] deactivate_super+0x37/0x58
#1: (&(&nilfs->ns_cptree_lock)->rlock){+.+...}, at: [<791bf659>] nilfs_put_root+0x23/0x5a
Preemption disabled at:[<791bf659>] nilfs_put_root+0x23/0x5a
CPU: 0 PID: 32676 Comm: umount.nilfs2 Not tainted 3.14.0+ #2
Hardware name: Dell Computer Corporation Dimension 2350/07W080, BIOS A01 12/17/2002
Call Trace:
dump_stack+0x4b/0x75
__might_sleep+0x111/0x16f
mutex_lock_nested+0x1e/0x3ad
kernfs_remove+0x12/0x26
sysfs_remove_dir+0x3d/0x62
kobject_del+0x13/0x38
nilfs_sysfs_delete_snapshot_group+0xb/0xd
nilfs_put_root+0x2a/0x5a
nilfs_detach_log_writer+0x1ab/0x2c1
nilfs_put_super+0x13/0x68
generic_shutdown_super+0x60/0xd1
kill_block_super+0x1d/0x60
deactivate_locked_super+0x22/0x3f
deactivate_super+0x3e/0x58
mntput_no_expire+0xe2/0x141
SyS_oldumount+0x70/0xa5
syscall_call+0x7/0xb
The reason of the issue was placement of
nilfs_sysfs_{create/delete}_snapshot_group() call under
nilfs->ns_cptree_lock protection. But this protection is unnecessary and
wrong solution. The second version of the patch fixes this issue.
[fengguang.wu@intel.com: nilfs_sysfs_create_mounted_snapshots_group can be static]
Reported-by: Michael L. Semon <mlsemon35@gmail.com>
Signed-off-by: Vyacheslav Dubeyko <Vyacheslav.Dubeyko@hgst.com>
Cc: Vyacheslav Dubeyko <slava@dubeyko.com>
Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Tested-by: Michael L. Semon <mlsemon35@gmail.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/nilfs2/the_nilfs.c b/fs/nilfs2/the_nilfs.c
index 59d5008..9da25fe 100644
--- a/fs/nilfs2/the_nilfs.c
+++ b/fs/nilfs2/the_nilfs.c
@@ -98,6 +98,7 @@
{
might_sleep();
if (nilfs_init(nilfs)) {
+ nilfs_sysfs_delete_device_group(nilfs);
brelse(nilfs->ns_sbh[0]);
brelse(nilfs->ns_sbh[1]);
}
@@ -641,6 +642,10 @@
if (err)
goto failed_sbh;
+ err = nilfs_sysfs_create_device_group(sb);
+ if (err)
+ goto failed_sbh;
+
set_nilfs_init(nilfs);
err = 0;
out:
@@ -741,12 +746,13 @@
{
struct rb_node **p, *parent;
struct nilfs_root *root, *new;
+ int err;
root = nilfs_lookup_root(nilfs, cno);
if (root)
return root;
- new = kmalloc(sizeof(*root), GFP_KERNEL);
+ new = kzalloc(sizeof(*root), GFP_KERNEL);
if (!new)
return NULL;
@@ -783,6 +789,12 @@
spin_unlock(&nilfs->ns_cptree_lock);
+ err = nilfs_sysfs_create_snapshot_group(new);
+ if (err) {
+ kfree(new);
+ new = NULL;
+ }
+
return new;
}
@@ -791,6 +803,8 @@
if (atomic_dec_and_test(&root->count)) {
struct the_nilfs *nilfs = root->nilfs;
+ nilfs_sysfs_delete_snapshot_group(root);
+
spin_lock(&nilfs->ns_cptree_lock);
rb_erase(&root->rb_node, &nilfs->ns_cptree);
spin_unlock(&nilfs->ns_cptree_lock);