floppy: force media-change checks when clearing events#800
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blktests-ci[bot] wants to merge 1 commit intolinus-master_basefrom
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floppy: force media-change checks when clearing events#800blktests-ci[bot] wants to merge 1 commit intolinus-master_basefrom
blktests-ci[bot] wants to merge 1 commit intolinus-master_basefrom
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floppy_open() tries to make blocking read/write opens perform a fresh media-change check by clearing drive_state[drive].last_checked before calling disk_check_media_change(). That timestamp is also updated by disk_change() when another FDC operation observes that the disk-change line is clear. The worker path that calls disk_change() is not serialized by the floppy_mutex/open_lock pair held by floppy_open(). A worker can therefore store a recent jiffies value after floppy_open() stores zero and before the synchronous disk_check_media_change() call reaches floppy_check_events(). The checkfreq throttle can then treat the media-change state as fresh and skip the hardware poll that the open path explicitly tried to force. Use the block layer's clearing mask instead of a racy timestamp sentinel. When DISK_EVENT_MEDIA_CHANGE is being synchronously cleared, bypass the checkfreq throttle and poll the drive. Periodic event checks still use last_checked to avoid unnecessary polling, and floppy_open() no longer needs to write last_checked itself. Signed-off-by: Cen Zhang <zzzccc427@gmail.com>
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Upstream branch: 6d35786 |
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Pull request for series with
subject: floppy: force media-change checks when clearing events
version: 1
url: https://patchwork.kernel.org/project/linux-block/list/?series=1090195