From: Jens Axboe Date: Thu, 17 Mar 2011 10:13:12 +0000 (+0100) Subject: fs: assign sb->s_bdi to default_backing_dev_info if the bdi is going away X-Git-Tag: v2.6.34.13~167 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=bc661f5d238569cae7ca9da01e12451b7785fb01;p=karo-tx-linux.git fs: assign sb->s_bdi to default_backing_dev_info if the bdi is going away commit 95f28604a65b1c40b6c6cd95e58439cd7ded3add upstream. We don't have proper reference counting for this yet, so we run into cases where the device is pulled and we OOPS on flushing the fs data. This happens even though the dirty inodes have already been migrated to the default_backing_dev_info. Reported-by: Torsten Hilbrich Tested-by: Torsten Hilbrich Signed-off-by: Jens Axboe Signed-off-by: Paul Gortmaker --- diff --git a/fs/super.c b/fs/super.c index 53040a673bf2..7123fa728af7 100644 --- a/fs/super.c +++ b/fs/super.c @@ -64,6 +64,7 @@ static struct super_block *alloc_super(struct file_system_type *type) goto out; } INIT_LIST_HEAD(&s->s_files); + s->s_bdi = &default_backing_dev_info; INIT_LIST_HEAD(&s->s_instances); INIT_HLIST_HEAD(&s->s_anon); INIT_LIST_HEAD(&s->s_inodes); @@ -962,6 +963,7 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void goto out_free_secdata; BUG_ON(!mnt->mnt_sb); WARN_ON(!mnt->mnt_sb->s_bdi); + WARN_ON(mnt->mnt_sb->s_bdi == &default_backing_dev_info); mnt->mnt_sb->s_flags |= MS_BORN; error = security_sb_kern_mount(mnt->mnt_sb, flags, secdata); diff --git a/fs/sync.c b/fs/sync.c index 92b228176f7c..5281fb372d59 100644 --- a/fs/sync.c +++ b/fs/sync.c @@ -33,7 +33,7 @@ static int __sync_filesystem(struct super_block *sb, int wait) * This should be safe, as we require bdi backing to actually * write out data in the first place */ - if (!sb->s_bdi || sb->s_bdi == &noop_backing_dev_info) + if (sb->s_bdi == &noop_backing_dev_info) return 0; if (sb->s_qcop && sb->s_qcop->quota_sync) @@ -110,7 +110,7 @@ restart: spin_unlock(&sb_lock); down_read(&sb->s_umount); - if (!(sb->s_flags & MS_RDONLY) && sb->s_root && sb->s_bdi) + if (!(sb->s_flags & MS_RDONLY) && sb->s_root) __sync_filesystem(sb, wait); up_read(&sb->s_umount); diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 707d0dc6da0f..7bd17d294b83 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -634,7 +634,7 @@ static void bdi_prune_sb(struct backing_dev_info *bdi) spin_lock(&sb_lock); list_for_each_entry(sb, &super_blocks, s_list) { if (sb->s_bdi == bdi) - sb->s_bdi = NULL; + sb->s_bdi = &default_backing_dev_info; } spin_unlock(&sb_lock); }