diff options
author | Baokun Li <libaokun1@huawei.com> | 2024-03-07 13:10:18 +0300 |
---|---|---|
committer | Gao Xiang <hsiangkao@linux.alibaba.com> | 2024-03-10 13:41:32 +0300 |
commit | 0f28be64d132aaf95d06375c8002ad9ecea69d71 (patch) | |
tree | d4de78196a8fc22849f523a638fa5178a255a62f | |
parent | 706fd68fce3a5737286afd3e6422ab9258bd3e94 (diff) | |
download | linux-0f28be64d132aaf95d06375c8002ad9ecea69d71.tar.xz |
erofs: fix lockdep false positives on initializing erofs_pseudo_mnt
Lockdep reported the following issue when mounting erofs with a domain_id:
============================================
WARNING: possible recursive locking detected
6.8.0-rc7-xfstests #521 Not tainted
--------------------------------------------
mount/396 is trying to acquire lock:
ffff907a8aaaa0e0 (&type->s_umount_key#50/1){+.+.}-{3:3},
at: alloc_super+0xe3/0x3d0
but task is already holding lock:
ffff907a8aaa90e0 (&type->s_umount_key#50/1){+.+.}-{3:3},
at: alloc_super+0xe3/0x3d0
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&type->s_umount_key#50/1);
lock(&type->s_umount_key#50/1);
*** DEADLOCK ***
May be due to missing lock nesting notation
2 locks held by mount/396:
#0: ffff907a8aaa90e0 (&type->s_umount_key#50/1){+.+.}-{3:3},
at: alloc_super+0xe3/0x3d0
#1: ffffffffc00e6f28 (erofs_domain_list_lock){+.+.}-{3:3},
at: erofs_fscache_register_fs+0x3d/0x270 [erofs]
stack backtrace:
CPU: 1 PID: 396 Comm: mount Not tainted 6.8.0-rc7-xfstests #521
Call Trace:
<TASK>
dump_stack_lvl+0x64/0xb0
validate_chain+0x5c4/0xa00
__lock_acquire+0x6a9/0xd50
lock_acquire+0xcd/0x2b0
down_write_nested+0x45/0xd0
alloc_super+0xe3/0x3d0
sget_fc+0x62/0x2f0
vfs_get_super+0x21/0x90
vfs_get_tree+0x2c/0xf0
fc_mount+0x12/0x40
vfs_kern_mount.part.0+0x75/0x90
kern_mount+0x24/0x40
erofs_fscache_register_fs+0x1ef/0x270 [erofs]
erofs_fc_fill_super+0x213/0x380 [erofs]
This is because the file_system_type of both erofs and the pseudo-mount
point of domain_id is erofs_fs_type, so two successive calls to
alloc_super() are considered to be using the same lock and trigger the
warning above.
Therefore add a nodev file_system_type called erofs_anon_fs_type in
fscache.c to silence this complaint. Because kern_mount() takes a
pointer to struct file_system_type, not its (string) name. So we don't
need to call register_filesystem(). In addition, call init_pseudo() in
erofs_anon_init_fs_context() as suggested by Al Viro, so that we can
remove erofs_fc_fill_pseudo_super(), erofs_fc_anon_get_tree(), and
erofs_anon_context_ops.
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Fixes: a9849560c55e ("erofs: introduce a pseudo mnt to manage shared cookies")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-and-tested-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Yang Erkun <yangerkun@huawei.com>
Link: https://lore.kernel.org/r/20240307101018.2021925-1-libaokun1@huawei.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
-rw-r--r-- | fs/erofs/fscache.c | 15 | ||||
-rw-r--r-- | fs/erofs/internal.h | 1 | ||||
-rw-r--r-- | fs/erofs/super.c | 30 |
3 files changed, 15 insertions, 31 deletions
diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c index 89a7c2453aae..122a4753ecea 100644 --- a/fs/erofs/fscache.c +++ b/fs/erofs/fscache.c @@ -3,6 +3,7 @@ * Copyright (C) 2022, Alibaba Cloud * Copyright (C) 2022, Bytedance Inc. All rights reserved. */ +#include <linux/pseudo_fs.h> #include <linux/fscache.h> #include "internal.h" @@ -12,6 +13,18 @@ static LIST_HEAD(erofs_domain_list); static LIST_HEAD(erofs_domain_cookies_list); static struct vfsmount *erofs_pseudo_mnt; +static int erofs_anon_init_fs_context(struct fs_context *fc) +{ + return init_pseudo(fc, EROFS_SUPER_MAGIC) ? 0 : -ENOMEM; +} + +static struct file_system_type erofs_anon_fs_type = { + .owner = THIS_MODULE, + .name = "pseudo_erofs", + .init_fs_context = erofs_anon_init_fs_context, + .kill_sb = kill_anon_super, +}; + struct erofs_fscache_request { struct erofs_fscache_request *primary; struct netfs_cache_resources cache_resources; @@ -381,7 +394,7 @@ static int erofs_fscache_init_domain(struct super_block *sb) goto out; if (!erofs_pseudo_mnt) { - struct vfsmount *mnt = kern_mount(&erofs_fs_type); + struct vfsmount *mnt = kern_mount(&erofs_anon_fs_type); if (IS_ERR(mnt)) { err = PTR_ERR(mnt); goto out; diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h index 65db0250f146..f8623113be6c 100644 --- a/fs/erofs/internal.h +++ b/fs/erofs/internal.h @@ -385,7 +385,6 @@ struct erofs_map_dev { unsigned int m_deviceid; }; -extern struct file_system_type erofs_fs_type; extern const struct super_operations erofs_sops; extern const struct address_space_operations erofs_raw_access_aops; diff --git a/fs/erofs/super.c b/fs/erofs/super.c index 5f60f163bd56..24788c230b49 100644 --- a/fs/erofs/super.c +++ b/fs/erofs/super.c @@ -579,13 +579,6 @@ static const struct export_operations erofs_export_ops = { .get_parent = erofs_get_parent, }; -static int erofs_fc_fill_pseudo_super(struct super_block *sb, struct fs_context *fc) -{ - static const struct tree_descr empty_descr = {""}; - - return simple_fill_super(sb, EROFS_SUPER_MAGIC, &empty_descr); -} - static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc) { struct inode *inode; @@ -712,11 +705,6 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc) return 0; } -static int erofs_fc_anon_get_tree(struct fs_context *fc) -{ - return get_tree_nodev(fc, erofs_fc_fill_pseudo_super); -} - static int erofs_fc_get_tree(struct fs_context *fc) { struct erofs_fs_context *ctx = fc->fs_private; @@ -789,20 +777,10 @@ static const struct fs_context_operations erofs_context_ops = { .free = erofs_fc_free, }; -static const struct fs_context_operations erofs_anon_context_ops = { - .get_tree = erofs_fc_anon_get_tree, -}; - static int erofs_init_fs_context(struct fs_context *fc) { struct erofs_fs_context *ctx; - /* pseudo mount for anon inodes */ - if (fc->sb_flags & SB_KERNMOUNT) { - fc->ops = &erofs_anon_context_ops; - return 0; - } - ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); if (!ctx) return -ENOMEM; @@ -824,12 +802,6 @@ static void erofs_kill_sb(struct super_block *sb) { struct erofs_sb_info *sbi; - /* pseudo mount for anon inodes */ - if (sb->s_flags & SB_KERNMOUNT) { - kill_anon_super(sb); - return; - } - if (erofs_is_fscache_mode(sb)) kill_anon_super(sb); else @@ -868,7 +840,7 @@ static void erofs_put_super(struct super_block *sb) erofs_fscache_unregister_fs(sb); } -struct file_system_type erofs_fs_type = { +static struct file_system_type erofs_fs_type = { .owner = THIS_MODULE, .name = "erofs", .init_fs_context = erofs_init_fs_context, |