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block: fix ext_devt_idr handling

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commit 7b74e91278 upstream.

While adding and removing a lot of disks disks and partitions this
sometimes shows up:

  WARNING: at fs/sysfs/dir.c:512 sysfs_add_one+0xc9/0x130() (Not tainted)
  Hardware name:
  sysfs: cannot create duplicate filename '/dev/block/259:751'
  Modules linked in: raid1 autofs4 bnx2fc cnic uio fcoe libfcoe libfc 8021q scsi_transport_fc scsi_tgt garp stp llc sunrpc cpufreq_ondemand powernow_k8 freq_table mperf ipv6 dm_mirror dm_region_hash dm_log power_meter microcode dcdbas serio_raw amd64_edac_mod edac_core edac_mce_amd i2c_piix4 i2c_core k10temp bnx2 sg ixgbe dca mdio ext4 mbcache jbd2 dm_round_robin sr_mod cdrom sd_mod crc_t10dif ata_generic pata_acpi pata_atiixp ahci mptsas mptscsih mptbase scsi_transport_sas dm_multipath dm_mod [last unloaded: scsi_wait_scan]
  Pid: 44103, comm: async/16 Not tainted 2.6.32-195.el6.x86_64 #1
  Call Trace:
    warn_slowpath_common+0x87/0xc0
    warn_slowpath_fmt+0x46/0x50
    sysfs_add_one+0xc9/0x130
    sysfs_do_create_link+0x12b/0x170
    sysfs_create_link+0x13/0x20
    device_add+0x317/0x650
    idr_get_new+0x13/0x50
    add_partition+0x21c/0x390
    rescan_partitions+0x32b/0x470
    sd_open+0x81/0x1f0 [sd_mod]
    __blkdev_get+0x1b6/0x3c0
    blkdev_get+0x10/0x20
    register_disk+0x155/0x170
    add_disk+0xa6/0x160
    sd_probe_async+0x13b/0x210 [sd_mod]
    add_wait_queue+0x46/0x60
    async_thread+0x102/0x250
    default_wake_function+0x0/0x20
    async_thread+0x0/0x250
    kthread+0x96/0xa0
    child_rip+0xa/0x20
    kthread+0x0/0xa0
    child_rip+0x0/0x20

This most likely happens because dev_t is freed while the number is
still used and idr_get_new() is not protected on every use.  The fix
adds a mutex where it wasn't before and moves the dev_t free function so
it is called after device del.

Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tomas Henzl 2013-02-27 17:03:32 -08:00 committed by Greg Kroah-Hartman
parent 5978ac7c68
commit 6ee1df3bff
2 changed files with 6 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
block/genhd.c
View file

@ -420,14 +420,18 @@ int blk_alloc_devt(struct hd_struct *part, dev_t *devt)
do {
if (!idr_pre_get(&ext_devt_idr, GFP_KERNEL))
return -ENOMEM;
mutex_lock(&ext_devt_mutex);
rc = idr_get_new(&ext_devt_idr, part, &idx);
mutex_unlock(&ext_devt_mutex);
} while (rc == -EAGAIN);
if (rc)
return rc;
if (idx > MAX_EXT_DEVT) {
mutex_lock(&ext_devt_mutex);
idr_remove(&ext_devt_idr, idx);
mutex_unlock(&ext_devt_mutex);
return -EBUSY;
}
@ -644,7 +648,6 @@ void del_gendisk(struct gendisk *disk)
disk_part_iter_exit(&piter);
invalidate_partition(disk, 0);
blk_free_devt(disk_to_dev(disk)->devt);
set_capacity(disk, 0);
disk->flags &= ~GENHD_FL_UP;
@ -662,6 +665,7 @@ void del_gendisk(struct gendisk *disk)
if (!sysfs_deprecated)
sysfs_remove_link(block_depr, dev_name(disk_to_dev(disk)));
device_del(disk_to_dev(disk));
blk_free_devt(disk_to_dev(disk)->devt);
}
EXPORT_SYMBOL(del_gendisk);

2
block/partition-generic.c
View file

@ -249,11 +249,11 @@ void delete_partition(struct gendisk *disk, int partno)
if (!part)
return;
blk_free_devt(part_devt(part));
rcu_assign_pointer(ptbl->part[partno], NULL);
rcu_assign_pointer(ptbl->last_lookup, NULL);
kobject_put(part->holder_dir);
device_del(part_to_dev(part));
blk_free_devt(part_devt(part));
hd_struct_put(part);
}