Re: How can I force a read?

From: Pavel Machek (pavel@suse.cz)
Date: Thu May 18 2000 - 16:13:54 EDT

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    Hi!

    > > How can I force a read from a block device after a
    > > write? Basically, if I do a write to some partition
    > > of a disk & perform a read of the same partition of
    > > the same disk(to verify whether the data has been
    > > written properly), a read is not actually performed
    > > as the buffer cache's dirty bit is not set. Even if
    > > I try to do a sync by calling the sync system call &
    > > then doing a read also does'nt actually perform the
    > > read, instead it takes from the buffer cache & gives
    > > the data back. Is there a way to tell the fs
    > > to force an actual read from the disk?
    >
    > These 2 ioctl()s against disk devices (e.g. sd and hd)
    > look like they could be of interest:
    >
    > BLKFLSBUF [instructs disk subsystem to flush buffers]

    It would be nice if some userland utility existed that would do
    this... Or is there one?
                                                                    Pavel

    -- 
    I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care."
    Panos Katsaloulis describing me w.r.t. patents me at discuss@linmodems.org
    

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