path: root/fs/nfs/super.c
diff options
authorJan Kara <jack@suse.cz>2017-05-04 09:02:42 +0200
committerJens Axboe <axboe@fb.com>2017-05-04 07:57:46 -0600
commit9052c7cf492d8c52c556f9536c4a9483fbfe4d73 (patch)
tree564affcf71ade396f480cc433cdb2924c20ed52d /fs/nfs/super.c
parenteabe06595d62cfa9278e2cd012df614bc68a7042 (diff)
nfs: Fix bdi handling for cloned superblocks
In commit 0d3b12584972 "nfs: Convert to separately allocated bdi" I have wrongly cloned bdi reference in nfs_clone_super(). Further inspection has shown that originally the code was actually allocating a new bdi (in ->clone_server callback) which was later registered in nfs_fs_mount_common() and used for sb->s_bdi in nfs_initialise_sb(). This could later result in bdi for the original superblock not getting unregistered when that superblock got shutdown (as the cloned sb still held bdi reference) and later when a new superblock was created under the same anonymous device number, a clash in sysfs has happened on bdi registration: ------------[ cut here ]------------ WARNING: CPU: 1 PID: 10284 at /linux-next/fs/sysfs/dir.c:31 sysfs_warn_dup+0x64/0x74 sysfs: cannot create duplicate filename '/devices/virtual/bdi/0:32' Modules linked in: axp20x_usb_power gpio_axp209 nvmem_sunxi_sid sun4i_dma sun4i_ss virt_dma CPU: 1 PID: 10284 Comm: mount.nfs Not tainted 4.11.0-rc4+ #14 Hardware name: Allwinner sun7i (A20) Family [<c010f19c>] (unwind_backtrace) from [<c010bc74>] (show_stack+0x10/0x14) [<c010bc74>] (show_stack) from [<c03c6e24>] (dump_stack+0x78/0x8c) [<c03c6e24>] (dump_stack) from [<c0122200>] (__warn+0xe8/0x100) [<c0122200>] (__warn) from [<c0122250>] (warn_slowpath_fmt+0x38/0x48) [<c0122250>] (warn_slowpath_fmt) from [<c02ac178>] (sysfs_warn_dup+0x64/0x74) [<c02ac178>] (sysfs_warn_dup) from [<c02ac254>] (sysfs_create_dir_ns+0x84/0x94) [<c02ac254>] (sysfs_create_dir_ns) from [<c03c8b8c>] (kobject_add_internal+0x9c/0x2ec) [<c03c8b8c>] (kobject_add_internal) from [<c03c8e24>] (kobject_add+0x48/0x98) [<c03c8e24>] (kobject_add) from [<c048d75c>] (device_add+0xe4/0x5a0) [<c048d75c>] (device_add) from [<c048ddb4>] (device_create_groups_vargs+0xac/0xbc) [<c048ddb4>] (device_create_groups_vargs) from [<c048dde4>] (device_create_vargs+0x20/0x28) [<c048dde4>] (device_create_vargs) from [<c02075c8>] (bdi_register_va+0x44/0xfc) [<c02075c8>] (bdi_register_va) from [<c023d378>] (super_setup_bdi_name+0x48/0xa4) [<c023d378>] (super_setup_bdi_name) from [<c0312ef4>] (nfs_fill_super+0x1a4/0x204) [<c0312ef4>] (nfs_fill_super) from [<c03133f0>] (nfs_fs_mount_common+0x140/0x1e8) [<c03133f0>] (nfs_fs_mount_common) from [<c03335cc>] (nfs4_remote_mount+0x50/0x58) [<c03335cc>] (nfs4_remote_mount) from [<c023ef98>] (mount_fs+0x14/0xa4) [<c023ef98>] (mount_fs) from [<c025cba0>] (vfs_kern_mount+0x54/0x128) [<c025cba0>] (vfs_kern_mount) from [<c033352c>] (nfs_do_root_mount+0x80/0xa0) [<c033352c>] (nfs_do_root_mount) from [<c0333818>] (nfs4_try_mount+0x28/0x3c) [<c0333818>] (nfs4_try_mount) from [<c0313874>] (nfs_fs_mount+0x2cc/0x8c4) [<c0313874>] (nfs_fs_mount) from [<c023ef98>] (mount_fs+0x14/0xa4) [<c023ef98>] (mount_fs) from [<c025cba0>] (vfs_kern_mount+0x54/0x128) [<c025cba0>] (vfs_kern_mount) from [<c02600f0>] (do_mount+0x158/0xc7c) [<c02600f0>] (do_mount) from [<c0260f98>] (SyS_mount+0x8c/0xb4) [<c0260f98>] (SyS_mount) from [<c0107840>] (ret_fast_syscall+0x0/0x3c) Fix the problem by always creating new bdi for a superblock as we used to do. Reported-and-tested-by: Corentin Labbe <clabbe.montjoie@gmail.com> Fixes: 0d3b12584972ce5781179ad3f15cca3cdb5cae05 Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'fs/nfs/super.c')
1 files changed, 10 insertions, 18 deletions
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index dc69314d455e..2f3822a4a7d5 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -2321,11 +2321,10 @@ inline void nfs_initialise_sb(struct super_block *sb)
* Finish setting up an NFS2/3 superblock
-int nfs_fill_super(struct super_block *sb, struct nfs_mount_info *mount_info)
+void nfs_fill_super(struct super_block *sb, struct nfs_mount_info *mount_info)
struct nfs_parsed_mount_data *data = mount_info->parsed;
struct nfs_server *server = NFS_SB(sb);
- int ret;
sb->s_blocksize_bits = 0;
sb->s_blocksize = 0;
@@ -2343,21 +2342,13 @@ int nfs_fill_super(struct super_block *sb, struct nfs_mount_info *mount_info)
- ret = super_setup_bdi_name(sb, "%u:%u", MAJOR(server->s_dev),
- MINOR(server->s_dev));
- if (ret)
- return ret;
- sb->s_bdi->ra_pages = server->rpages * NFS_MAX_READAHEAD;
- return 0;
* Finish setting up a cloned NFS2/3/4 superblock
-int nfs_clone_super(struct super_block *sb, struct nfs_mount_info *mount_info)
+void nfs_clone_super(struct super_block *sb, struct nfs_mount_info *mount_info)
const struct super_block *old_sb = mount_info->cloned->sb;
struct nfs_server *server = NFS_SB(sb);
@@ -2377,10 +2368,6 @@ int nfs_clone_super(struct super_block *sb, struct nfs_mount_info *mount_info)
- sb->s_bdi = bdi_get(old_sb->s_bdi);
- return 0;
static int nfs_compare_mount_options(const struct super_block *s, const struct nfs_server *b, int flags)
@@ -2600,14 +2587,19 @@ struct dentry *nfs_fs_mount_common(struct nfs_server *server,
server = NULL;
} else {
+ error = super_setup_bdi_name(s, "%u:%u", MAJOR(server->s_dev),
+ MINOR(server->s_dev));
+ if (error) {
+ mntroot = ERR_PTR(error);
+ goto error_splat_super;
+ }
+ s->s_bdi->ra_pages = server->rpages * NFS_MAX_READAHEAD;
server->super = s;
if (!s->s_root) {
/* initial superblock/root creation */
- error = mount_info->fill_super(s, mount_info);
- if (error)
- goto error_splat_super;
+ mount_info->fill_super(s, mount_info);
nfs_get_cache_cookie(s, mount_info->parsed, mount_info->cloned);