• Linus Torvalds's avatar
    Make wait_for_device_probe() also do scsi_complete_async_scans() · eea03c20
    Linus Torvalds authored
    Commit a7a20d10 ("sd: limit the scope of the async probe domain")
    make the SCSI device probing run device discovery in it's own async
    domain.
    
    However, as a result, the partition detection was no longer synchronized
    by async_synchronize_full() (which, despite the name, only synchronizes
    the global async space, not all of them).  Which in turn meant that
    "wait_for_device_probe()" would not wait for the SCSI partitions to be
    parsed.
    
    And "wait_for_device_probe()" was what the boot time init code relied on
    for mounting the root filesystem.
    
    Now, most people never noticed this, because not only is it
    timing-dependent, but modern distributions all use initrd.  So the root
    filesystem isn't actually on a disk at all.  And then before they
    actually mount the final disk filesystem, they will have loaded the
    scsi-wait-scan module, which not only does the expected
    wait_for_device_probe(), but also does scsi_complete_async_scans().
    
    [ Side note: scsi_complete_async_scans() had also been partially broken,
      but that was fixed in commit 43a8d39d ("fix async probe
      regression"), so that same commit a7a20d10 had actually broken
      setups even if you used scsi-wait-scan explicitly ]
    
    Solve this problem by just moving the scsi_complete_async_scans() call
    into wait_for_device_probe().  Everybody who wants to wait for device
    probing to finish really wants the SCSI probing to complete, so there's
    no reason not to do this.
    
    So now "wait_for_device_probe()" really does what the name implies, and
    properly waits for device probing to finish.  This also removes the now
    unnecessary extra calls to scsi_complete_async_scans().
    Reported-and-tested-by: default avatarArtem S. Tashkinov <t.artem@mailcity.com>
    Cc: Dan Williams <dan.j.williams@gmail.com>
    Cc: Alan Stern <stern@rowland.harvard.edu>
    Cc: James Bottomley <jbottomley@parallels.com>
    Cc: Borislav Petkov <bp@amd64.org>
    Cc: linux-scsi <linux-scsi@vger.kernel.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    eea03c20
scsi_wait_scan.c 958 Bytes