On 05/04/2017 01:02 AM, Jan Kara wrote: > 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@xxxxxxxxx> > Fixes: 0d3b12584972ce5781179ad3f15cca3cdb5cae05 > Signed-off-by: Jan Kara <jack@xxxxxxx> > --- > fs/nfs/internal.h | 6 +++--- > fs/nfs/super.c | 28 ++++++++++------------------ > 2 files changed, 13 insertions(+), 21 deletions(-) > > Hi Jens, > > can you please merge this fix to my series converting BDI handling in > filesystems? Thanks! Yep, added for a later pull in this merge window. Thanks Jan. -- Jens Axboe
