From fca39346a55bb7196888ffc77d9e3557340d1d0b Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Wed, 12 Apr 2017 12:24:28 +0200 Subject: [PATCH] fs: Provide infrastructure for dynamic BDIs in filesystems Provide helper functions for setting up dynamically allocated backing_dev_info structures for filesystems and cleaning them up on superblock destruction. CC: linux-mtd@lists.infradead.org CC: linux-nfs@vger.kernel.org CC: Petr Vandrovec CC: linux-nilfs@vger.kernel.org CC: cluster-devel@redhat.com CC: osd-dev@open-osd.org CC: codalist@coda.cs.cmu.edu CC: linux-afs@lists.infradead.org CC: ecryptfs@vger.kernel.org CC: linux-cifs@vger.kernel.org CC: ceph-devel@vger.kernel.org CC: linux-btrfs@vger.kernel.org CC: v9fs-developer@lists.sourceforge.net CC: lustre-devel@lists.lustre.org Reviewed-by: Christoph Hellwig Signed-off-by: Jan Kara Signed-off-by: Jens Axboe --- fs/super.c | 49 ++++++++++++++++++++++++++++++++ include/linux/backing-dev-defs.h | 2 +- include/linux/fs.h | 6 ++++ 3 files changed, 56 insertions(+), 1 deletion(-) diff --git a/fs/super.c b/fs/super.c index b8b6a086c03b..0f51a437c269 100644 --- a/fs/super.c +++ b/fs/super.c @@ -446,6 +446,11 @@ void generic_shutdown_super(struct super_block *sb) hlist_del_init(&sb->s_instances); spin_unlock(&sb_lock); up_write(&sb->s_umount); + if (sb->s_iflags & SB_I_DYNBDI) { + bdi_put(sb->s_bdi); + sb->s_bdi = &noop_backing_dev_info; + sb->s_iflags &= ~SB_I_DYNBDI; + } } EXPORT_SYMBOL(generic_shutdown_super); @@ -1255,6 +1260,50 @@ out: return ERR_PTR(error); } +/* + * Setup private BDI for given superblock. It gets automatically cleaned up + * in generic_shutdown_super(). + */ +int super_setup_bdi_name(struct super_block *sb, char *fmt, ...) +{ + struct backing_dev_info *bdi; + int err; + va_list args; + + bdi = bdi_alloc(GFP_KERNEL); + if (!bdi) + return -ENOMEM; + + bdi->name = sb->s_type->name; + + va_start(args, fmt); + err = bdi_register_va(bdi, NULL, fmt, args); + va_end(args); + if (err) { + bdi_put(bdi); + return err; + } + WARN_ON(sb->s_bdi != &noop_backing_dev_info); + sb->s_bdi = bdi; + sb->s_iflags |= SB_I_DYNBDI; + + return 0; +} +EXPORT_SYMBOL(super_setup_bdi_name); + +/* + * Setup private BDI for given superblock. I gets automatically cleaned up + * in generic_shutdown_super(). + */ +int super_setup_bdi(struct super_block *sb) +{ + static atomic_long_t bdi_seq = ATOMIC_LONG_INIT(0); + + return super_setup_bdi_name(sb, "%.28s-%ld", sb->s_type->name, + atomic_long_inc_return(&bdi_seq)); +} +EXPORT_SYMBOL(super_setup_bdi); + /* * This is an internal function, please use sb_end_{write,pagefault,intwrite} * instead. diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h index e66d4722db8e..866c433e7d32 100644 --- a/include/linux/backing-dev-defs.h +++ b/include/linux/backing-dev-defs.h @@ -146,7 +146,7 @@ struct backing_dev_info { congested_fn *congested_fn; /* Function pointer if device is md/dm */ void *congested_data; /* Pointer to aux data for congested func */ - char *name; + const char *name; struct kref refcnt; /* Reference counter for the structure */ unsigned int capabilities; /* Device capabilities */ diff --git a/include/linux/fs.h b/include/linux/fs.h index 7251f7bb45e8..98cf14ea78c0 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1272,6 +1272,9 @@ struct mm_struct; /* sb->s_iflags to limit user namespace mounts */ #define SB_I_USERNS_VISIBLE 0x00000010 /* fstype already mounted */ +/* Temporary flag until all filesystems are converted to dynamic bdis */ +#define SB_I_DYNBDI 0x00000100 + /* Possible states of 'frozen' field */ enum { SB_UNFROZEN = 0, /* FS is unfrozen */ @@ -2121,6 +2124,9 @@ extern int vfs_ustat(dev_t, struct kstatfs *); extern int freeze_super(struct super_block *super); extern int thaw_super(struct super_block *super); extern bool our_mnt(struct vfsmount *mnt); +extern __printf(2, 3) +int super_setup_bdi_name(struct super_block *sb, char *fmt, ...); +extern int super_setup_bdi(struct super_block *sb); extern int current_umask(void); -- 2.20.1