block: remove redundant GD_NEED_PART_SCAN in add_disk_final()#966
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block: remove redundant GD_NEED_PART_SCAN in add_disk_final()#966blktests-ci[bot] wants to merge 1 commit into
blktests-ci[bot] wants to merge 1 commit into
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add_disk_final() sets GD_NEED_PART_SCAN before calling bdev_add(), then calls disk_scan_partitions() which sets the flag itself. The early set is redundant and introduces a race. Between bdev_add() and disk_scan_partitions(), concurrent openers (multipathd, blkid, LVM) see the flag in blkdev_get_whole() and trigger bdev_disk_changed(). When disk_scan_partitions() then runs, it calls bdev_disk_changed() again, dropping the partitions the concurrent opener already created before re-adding them, which can result in transient partition disappearances. The race is observable by inserting an msleep() between bdev_add() and disk_scan_partitions() while running concurrent open() calls during device bind. Without artificial delay, it manifests under scheduling pressure during boot on systems with aggressive device scanners (multipathd, systemd-udevd). Therefore, do not set GD_NEED_PART_SCAN in add_disk_final(). Other GD_NEED_PART_SCAN consumers (blkdev_get_whole(), sd_need_revalidate()) should not be affected as the flag is set internally by disk_scan_partitions(). The retry-on-next-open intention from commit e5cfefa ("block: fix scan partition for exclusively open device again") should also not be affected as the early return paths in disk_scan_partitions() should be unreachable at device registration time (bd_holder is NULL and open_partitions is zero). Fixes: e5cfefa ("block: fix scan partition for exclusively open device again") Cc: stable@vger.kernel.org Signed-off-by: Connor Williamson <connordw@amazon.com>
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Upstream branch: 062871f |
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Pull request for series with
subject: block: remove redundant GD_NEED_PART_SCAN in add_disk_final()
version: 1
url: https://patchwork.kernel.org/project/linux-block/list/?series=1111700