69 lines
2.6 KiB
Diff
69 lines
2.6 KiB
Diff
From: Alexey Svistunov <svalx@svalx.net>
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Date: 2017-02-17 16:07:00 +0300
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Subject: open device with O_NONBLOCK option
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References: https://savannah.gnu.org/patch/?9263, bnc#94449
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Upstream: submitted
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When running the 2.6 kernel, "mt -f /dev/nst0 status" blocks if there is
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no media in the drive. The same occurs for other commands.
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When running the 2.4.24 kernel, "mt -f /dev/nst0 status" does not block
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when there is no tape in the drive.
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This behavior change is documented for the 2.6 kernel (see
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kernel-source-2.6.3/Documentation/scsi/st.txt for the full doc):
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If the open option O_NONBLOCK is used, open succeeds even if the
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drive is not ready. If O_NONBLOCK is not used, the driver waits for
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the drive to become ready. If this does not happen in ST_BLOCK_SECONDS
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seconds, open fails with the errno value EIO. With O_NONBLOCK the
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device can be opened for writing even if there is a write protected
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tape in the drive (commands trying to write something return error if
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attempted).
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It appears that the use of O_NONBLOCK is safe with pre-2.6 kernels.
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Suggest adding the use of O_NONBLOCK when opening the device. As it is,
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for long-running commands such as "fsf", one cannot tell if the command is
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progressing or if it's blocking waiting for media.
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Index: src/mt.c
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===================================================================
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--- src/mt.c.orig
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+++ src/mt.c
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@@ -332,11 +332,11 @@ main (int argc, char **argv)
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#ifdef MTERASE
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case MTERASE:
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#endif
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- tapedesc = rmtopen (tapedev, O_WRONLY, 0, rsh_command_option);
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+ tapedesc = rmtopen (tapedev, O_WRONLY | O_NONBLOCK, 0, rsh_command_option);
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break;
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default:
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- tapedesc = rmtopen (tapedev, O_RDONLY, 0, rsh_command_option);
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+ tapedesc = rmtopen (tapedev, O_RDONLY | O_NONBLOCK, 0, rsh_command_option);
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}
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if (tapedesc == -1)
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Index: src/util.c
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===================================================================
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--- src/util.c.orig
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+++ src/util.c
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@@ -799,14 +799,14 @@ open_archive (char *file)
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copy_in = process_copy_in;
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if (copy_function == copy_in)
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- fd = rmtopen (file, O_RDONLY | O_BINARY, MODE_RW, rsh_command_option);
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+ fd = rmtopen (file, O_RDONLY | O_BINARY | O_NONBLOCK, MODE_RW, rsh_command_option);
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else
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{
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if (!append_flag)
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- fd = rmtopen (file, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, MODE_RW,
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+ fd = rmtopen (file, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_NONBLOCK, MODE_RW,
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rsh_command_option);
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else
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- fd = rmtopen (file, O_RDWR | O_BINARY, MODE_RW, rsh_command_option);
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+ fd = rmtopen (file, O_RDWR | O_BINARY | O_NONBLOCK, MODE_RW, rsh_command_option);
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}
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return fd;
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