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| author | Ming Lei <ming.lei@canonical.com> | 2015-05-06 12:26:24 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2015-05-20 09:06:11 -0600 |
| commit | 06f0e9e68c0d81c7d822a405f6e35686a711c1fe (patch) | |
| tree | edeba14fd08414b99402b9b2d94a6faf34f1cded /drivers/block/loop.c | |
| parent | f8933667953e8e61bb6104f5ca88e32e85656a93 (diff) | |
| download | lwn-06f0e9e68c0d81c7d822a405f6e35686a711c1fe.tar.gz lwn-06f0e9e68c0d81c7d822a405f6e35686a711c1fe.zip | |
block: loop: fix another reread part failure
loop_clr_fd() can be run piggyback with lo_release(), and
under this situation, reread partition may always fail because
bd_mutex has been held already.
This patch detects the situation by the reference count, and
call __blkdev_reread_part() to avoid acquiring the lock again.
In the meantime, this patch switches to new kernel APIs
of blkdev_reread_part() and __blkdev_reread_part().
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Jarod Wilson <jarod@redhat.com>
Acked-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'drivers/block/loop.c')
| -rw-r--r-- | drivers/block/loop.c | 30 |
1 files changed, 26 insertions, 4 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index b3e294e529ec..2b99e34f4253 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -474,6 +474,28 @@ static int loop_flush(struct loop_device *lo) return loop_switch(lo, NULL); } +static void loop_reread_partitions(struct loop_device *lo, + struct block_device *bdev) +{ + int rc; + + /* + * bd_mutex has been held already in release path, so don't + * acquire it if this function is called in such case. + * + * If the reread partition isn't from release path, lo_refcnt + * must be at least one and it can only become zero when the + * current holder is released. + */ + if (!atomic_read(&lo->lo_refcnt)) + rc = __blkdev_reread_part(bdev); + else + rc = blkdev_reread_part(bdev); + if (rc) + pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n", + __func__, lo->lo_number, lo->lo_file_name, rc); +} + /* * loop_change_fd switched the backing store of a loopback device to * a new file. This is useful for operating system installers to free up @@ -522,7 +544,7 @@ static int loop_change_fd(struct loop_device *lo, struct block_device *bdev, fput(old_file); if (lo->lo_flags & LO_FLAGS_PARTSCAN) - ioctl_by_bdev(bdev, BLKRRPART, 0); + loop_reread_partitions(lo, bdev); return 0; out_putf: @@ -759,7 +781,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode, if (part_shift) lo->lo_flags |= LO_FLAGS_PARTSCAN; if (lo->lo_flags & LO_FLAGS_PARTSCAN) - ioctl_by_bdev(bdev, BLKRRPART, 0); + loop_reread_partitions(lo, bdev); /* Grab the block_device to prevent its destruction after we * put /dev/loopXX inode. Later in loop_clr_fd() we bdput(bdev). @@ -877,7 +899,7 @@ static int loop_clr_fd(struct loop_device *lo) blk_mq_unfreeze_queue(lo->lo_queue); if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev) - ioctl_by_bdev(bdev, BLKRRPART, 0); + loop_reread_partitions(lo, bdev); lo->lo_flags = 0; if (!part_shift) lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN; @@ -954,7 +976,7 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) !(lo->lo_flags & LO_FLAGS_PARTSCAN)) { lo->lo_flags |= LO_FLAGS_PARTSCAN; lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN; - ioctl_by_bdev(lo->lo_device, BLKRRPART, 0); + loop_reread_partitions(lo, lo->lo_device); } lo->lo_encrypt_key_size = info->lo_encrypt_key_size; |