forked from pool/parted
1f7315e780
Copy from home:puzel:branches:Base:System/parted via accept of submit request 30480 revision 2. Request was accepted with message: OBS-URL: https://build.opensuse.org/request/show/30480 OBS-URL: https://build.opensuse.org/package/show/Base:System/parted?expand=0&rev=14
97 lines
3.5 KiB
Diff
97 lines
3.5 KiB
Diff
From 2a6936fab4d4499a4b812dd330d3db50549029e0 Mon Sep 17 00:00:00 2001
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From: Hans de Goede <hdegoede@redhat.com>
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Date: Fri, 28 Aug 2009 17:05:55 +0200
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Subject: [PATCH] linux-commit: do not unnecessarily open partition device nodes
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After patching parted with my do-not-use-BLKPG patch, I started
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to get EBUSY errors on commit_to_os. Note this is not caused
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by the do-not-use-BLKPG patch, this was already happening, but
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parted was silently ignoring the errors (and the kernel was
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not notified of the changes, which is bad). The error now
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actually gets reported.
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The problem turns out to be in libparted/arch/linux.c's
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_flush_cache function, which walks all the partitions of the
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disk and does BLKFLSBUF calls on them. This causes the following:
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commit_to_os -> device_open -> fd = open /dev/sda ->
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_flush_cache -> for each /dev/sda# open, ioctl, close
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-> ioctl(fd, BLKRRPART) -> EBUSY
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What is happening here is that the:
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for each /dev/sda# open, ioctl, close
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Is causing udev change events for all the /dev/sda#
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nodes, which causes udev to call blkid on all these nodes
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(on systems which use DeviceKit), so blkid has /dev/sda# nodes
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open while BLKRRPART gets called on /dev/sda -> EBUSY.
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I've checked with two independend storage subsystem kernel
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developers, and /dev/sda and /dev/sda#, guarantee cache coherency
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now-a-days. So there is no need to do this for 2.6, which also
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eliminates the need to call _flush_cache() on device open at all.
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* libparted/arch/linux.c (_have_kern26): New function.
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(_flush_cache): For linux kernels 2.6 and newer, don't flush
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partition devices.
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(linux_open): Skip _flush_cache on newer kernels here, too.
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---
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libparted/arch/linux.c | 25 ++++++++++++++++++++++---
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1 files changed, 22 insertions(+), 3 deletions(-)
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Index: parted-1.9.0/libparted/arch/linux.c
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===================================================================
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--- parted-1.9.0.orig/libparted/arch/linux.c 2009-12-03 17:04:44.000000000 +0100
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+++ parted-1.9.0/libparted/arch/linux.c 2009-12-03 17:05:06.000000000 +0100
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@@ -601,6 +601,19 @@ _have_devfs ()
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return have_devfs = S_ISCHR(sb.st_mode) ? 1 : 0;
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}
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+static int
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+_have_kern26 ()
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+{
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+ static int have_kern26 = -1;
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+ int kver;
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+
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+ if (have_kern26 != -1)
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+ return have_kern26;
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+
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+ kver = _get_linux_version();
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+ return have_kern26 = kver >= KERNEL_VERSION (2,6,0) ? 1 : 0;
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+}
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+
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static void
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_device_set_sector_size (PedDevice* dev)
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{
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@@ -1374,8 +1387,8 @@ linux_is_busy (PedDevice* dev)
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return 0;
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}
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-/* we need to flush the master device, and all the partition devices,
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- * because there is no coherency between the caches.
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+/* we need to flush the master device, and with kernel < 2.6 all the partition
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+ * devices, because there is no coherency between the caches with old kernels.
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* We should only flush unmounted partition devices, because:
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* - there is never a need to flush them (we're not doing IO there)
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* - flushing a device that is mounted causes unnecessary IO, and can
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@@ -1393,6 +1406,10 @@ _flush_cache (PedDevice* dev)
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ioctl (arch_specific->fd, BLKFLSBUF);
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+ /* With linux-2.6.0 and newer, we're done. */
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+ if (_have_kern26())
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+ return;
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+
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for (i = 1; i < 16; i++) {
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char* name;
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int fd;
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@@ -1449,6 +1466,8 @@ retry:
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dev->read_only = 0;
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}
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+ /* With kernels < 2.6 flush cache for cache coherence issues */
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+ if (!_have_kern26())
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_flush_cache (dev);
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return 1;
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