Attachment 8908 Details for Bug 20074 – Patch to prevent kernel rescanning part way though writing the partition table (v2)

[patch] Patch to prevent kernel rescanning part way though writing the partition table (v2)

0001-Ensure-the-kernel-doesn-t-rescan-a-partially-written.patch (text/plain), 6.21 KB, created by Thierry Vignaud on 2017-01-30 16:36:39 CET

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Creator: Thierry Vignaud

Created: 2017-01-30 16:36:39 CET

Size: 6.21 KB

patch

obsolete

>From 33ecb2aa070f2a1a9ff3d109db4980c3f6aa153f Mon Sep 17 00:00:00 2001
>From: Martin Whitaker <mageia@martin-whitaker.me.uk>
>Date: Sat, 21 Jan 2017 19:38:55 +0000
>Subject: [PATCH 1/3] Ensure the kernel doesn't rescan a partially written
> partition table (mga#20074).
>
>When no partitions on a DOS-partitioned disk are mounted, the kernel
>automatically rescans the partition table when the file handle to the
>raw device is released. Currently the code opens and closes the raw
>device when writing the primary partition table and when writing each
>extended partition table segment. As the extended partition table
>segments form a linked list, this allows the kernel to get in and
>rescan the table when the list is not in a coherent state. This patch
>changes the code to open the raw device before writing the primary
>partition table and to close it only after writing the last extended
>partition table segment.
>
>The behaviour for other partition table types is unchanged.
>
>v2 (tvignaud): simplify by moving copies of noop funcs into the base class
>---
> perl-install/partition_table.pm     |  7 ++++---
> perl-install/partition_table/bsd.pm |  2 +-
> perl-install/partition_table/dos.pm | 22 ++++++++++++++++++----
> perl-install/partition_table/gpt.pm |  2 +-
> perl-install/partition_table/mac.pm |  2 +-
> perl-install/partition_table/raw.pm | 10 ++++++++++
> perl-install/partition_table/sun.pm |  2 +-
> 7 files changed, 36 insertions(+), 11 deletions(-)
>
>diff --git a/perl-install/partition_table.pm b/perl-install/partition_table.pm
>index c99cb10..049c7bb 100644
>--- a/perl-install/partition_table.pm
>+++ b/perl-install/partition_table.pm
>@@ -482,16 +482,17 @@ sub write {
>     #- it will never be writed back on partition table.
>     verifyParts($hd);
> 
>-    $hd->write(0, $hd->{primary}{raw}, $hd->{primary}{info}) or die "writing of partition table failed";
>-
>+    my $handle = $hd->start_write();
>+    $hd->write($handle, 0, $hd->{primary}{raw}, $hd->{primary}{info}) or die "writing of partition table failed";
>     #- should be fixed but a extended exist with no real extended partition, that blanks mbr!
> 	foreach (@{$hd->{extended}}) {
> 	    # in case of extended partitions, the start sector must be local to the partition
> 	    $_->{normal}{local_start} = $_->{normal}{start} - $_->{start};
> 	    $_->{extended} and $_->{extended}{local_start} = $_->{extended}{start} - $hd->{primary}{extended}{start};
> 
>-	    $hd->write($_->{start}, $_->{raw}) or die "writing of partition table failed";
>+	    $hd->write($handle, $_->{start}, $_->{raw}) or die "writing of partition table failed";
> 	}
>+    $hd->end_write($handle);
>     $hd->{isDirty} = 0;
> 
>     if (my $tell_kernel = delete $hd->{will_tell_kernel}) {
>diff --git a/perl-install/partition_table/bsd.pm b/perl-install/partition_table/bsd.pm
>index b27df6d..ec2a2ed 100644
>--- a/perl-install/partition_table/bsd.pm
>+++ b/perl-install/partition_table/bsd.pm
>@@ -90,7 +90,7 @@ sub read_one {
> # write the partition table (and extended ones)
> # for each entry, it uses fields: start, size, pt_type, active
> sub write($$$;$) {
>-    my ($hd, $sector, $pt, $info) = @_;
>+    my ($hd, $_handle, $sector, $pt, $info) = @_;
> 
>     #- handle testing for writing partition table on file only!
>     my $F;
>diff --git a/perl-install/partition_table/dos.pm b/perl-install/partition_table/dos.pm
>index 004c8a1..c56cdab 100644
>--- a/perl-install/partition_table/dos.pm
>+++ b/perl-install/partition_table/dos.pm
>@@ -236,10 +236,9 @@ sub read_one {
>     [ @pt ];
> }
> 
>-# write the partition table (and extended ones)
>-# for each entry, it uses fields: start, size, pt_type, active
>-sub write {
>-    my ($hd, $sector, $pt) = @_;
>+# prepare to write the partition table (and extended ones)
>+sub start_write {
>+    my ($hd) = @_;
> 
>     log::l("partition::dos::write $hd->{device}");
> 
>@@ -250,6 +249,16 @@ sub write {
> 	open $F, ">$file" or die "error opening test file $file";
>     } else {
> 	$F = partition_table::raw::openit($hd, 2) or die "error opening device $hd->{device} for writing";
>+    }
>+    $F;
>+}
>+
>+# write the partition table (and extended ones)
>+# for each entry, it uses fields: start, size, pt_type, active
>+sub write {
>+    my ($hd, $F, $sector, $pt) = @_;
>+
>+    if (!$::testing) {
>         c::lseek_sector(fileno($F), $sector, $offset) or return 0;
>     }
> 
>@@ -264,6 +273,11 @@ sub write {
>     1;
> }
> 
>+sub end_write {
>+    my ($hd, $F) = @_;
>+    close $F;
>+}
>+
> sub empty_raw { { raw => [ ({}) x $nb_primary ] } }
> 
> sub initialize { 
>diff --git a/perl-install/partition_table/gpt.pm b/perl-install/partition_table/gpt.pm
>index 3ac6673..df8ead3 100644
>--- a/perl-install/partition_table/gpt.pm
>+++ b/perl-install/partition_table/gpt.pm
>@@ -71,7 +71,7 @@ sub read_one {
> }
> 
> sub write {
>-    my ($hd, $_sector, $pt, $_info) = @_;
>+    my ($hd, $_handle, $_sector, $pt, $_info) = @_;
> 
>     my $partitions_killed;
> 
>diff --git a/perl-install/partition_table/mac.pm b/perl-install/partition_table/mac.pm
>index 547704b..78e5469 100644
>--- a/perl-install/partition_table/mac.pm
>+++ b/perl-install/partition_table/mac.pm
>@@ -193,7 +193,7 @@ sub read_one {
> }
> 
> sub write($$$;$) {
>-    my ($hd, $sector, $pt, $info) = @_;
>+    my ($hd, $_handle, $sector, $pt, $info) = @_;
> 
>     #- handle testing for writing partition table on file only!
>     my $F;
>diff --git a/perl-install/partition_table/raw.pm b/perl-install/partition_table/raw.pm
>index 7b4e7d5..e9b293b 100644
>--- a/perl-install/partition_table/raw.pm
>+++ b/perl-install/partition_table/raw.pm
>@@ -295,4 +295,14 @@ A test to check the integrity of data has failed.
> It means writing anything on the disk will end up with random, corrupted data.");
> }
> 
>+sub start_write {
>+    my ($_hd) = @_;
>+    1;
>+}
>+
>+sub end_write {
>+    my ($_hd, $_handle) = @_;
>+    1;
>+}
>+
> 1;
>diff --git a/perl-install/partition_table/sun.pm b/perl-install/partition_table/sun.pm
>index e2fd747..e665d01 100644
>--- a/perl-install/partition_table/sun.pm
>+++ b/perl-install/partition_table/sun.pm
>@@ -119,7 +119,7 @@ sub read_one {
> # write the partition table (and extended ones)
> # for each entry, it uses fields: start, size, pt_type, active
> sub write($$$;$) {
>-    my ($hd, $sector, $pt, $info) = @_;
>+    my ($hd, $_handle, $sector, $pt, $info) = @_;
> #    my ($csize, $wdsize) = (0, 0);
> 
>     #- handle testing for writing partition table on file only!
>-- 
>2.10.2
>

From 33ecb2aa070f2a1a9ff3d109db4980c3f6aa153f Mon Sep 17 00:00:00 2001
From: Martin Whitaker <mageia@martin-whitaker.me.uk>
Date: Sat, 21 Jan 2017 19:38:55 +0000
Subject: [PATCH 1/3] Ensure the kernel doesn't rescan a partially written
 partition table (mga#20074).

When no partitions on a DOS-partitioned disk are mounted, the kernel
automatically rescans the partition table when the file handle to the
raw device is released. Currently the code opens and closes the raw
device when writing the primary partition table and when writing each
extended partition table segment. As the extended partition table
segments form a linked list, this allows the kernel to get in and
rescan the table when the list is not in a coherent state. This patch
changes the code to open the raw device before writing the primary
partition table and to close it only after writing the last extended
partition table segment.

The behaviour for other partition table types is unchanged.

v2 (tvignaud): simplify by moving copies of noop funcs into the base class
---
 perl-install/partition_table.pm     |  7 ++++---
 perl-install/partition_table/bsd.pm |  2 +-
 perl-install/partition_table/dos.pm | 22 ++++++++++++++++++----
 perl-install/partition_table/gpt.pm |  2 +-
 perl-install/partition_table/mac.pm |  2 +-
 perl-install/partition_table/raw.pm | 10 ++++++++++
 perl-install/partition_table/sun.pm |  2 +-
 7 files changed, 36 insertions(+), 11 deletions(-)

diff --git a/perl-install/partition_table.pm b/perl-install/partition_table.pm
index c99cb10..049c7bb 100644
--- a/perl-install/partition_table.pm
+++ b/perl-install/partition_table.pm
@@ -482,16 +482,17 @@ sub write {
     #- it will never be writed back on partition table.
     verifyParts($hd);
 
-    $hd->write(0, $hd->{primary}{raw}, $hd->{primary}{info}) or die "writing of partition table failed";
-
+    my $handle = $hd->start_write();
+    $hd->write($handle, 0, $hd->{primary}{raw}, $hd->{primary}{info}) or die "writing of partition table failed";
     #- should be fixed but a extended exist with no real extended partition, that blanks mbr!
 	foreach (@{$hd->{extended}}) {
 	    # in case of extended partitions, the start sector must be local to the partition
 	    $_->{normal}{local_start} = $_->{normal}{start} - $_->{start};
 	    $_->{extended} and $_->{extended}{local_start} = $_->{extended}{start} - $hd->{primary}{extended}{start};
 
-	    $hd->write($_->{start}, $_->{raw}) or die "writing of partition table failed";
+	    $hd->write($handle, $_->{start}, $_->{raw}) or die "writing of partition table failed";
 	}
+    $hd->end_write($handle);
     $hd->{isDirty} = 0;
 
     if (my $tell_kernel = delete $hd->{will_tell_kernel}) {
diff --git a/perl-install/partition_table/bsd.pm b/perl-install/partition_table/bsd.pm
index b27df6d..ec2a2ed 100644
--- a/perl-install/partition_table/bsd.pm
+++ b/perl-install/partition_table/bsd.pm
@@ -90,7 +90,7 @@ sub read_one {
 # write the partition table (and extended ones)
 # for each entry, it uses fields: start, size, pt_type, active
 sub write($$$;$) {
-    my ($hd, $sector, $pt, $info) = @_;
+    my ($hd, $_handle, $sector, $pt, $info) = @_;
 
     #- handle testing for writing partition table on file only!
     my $F;
diff --git a/perl-install/partition_table/dos.pm b/perl-install/partition_table/dos.pm
index 004c8a1..c56cdab 100644
--- a/perl-install/partition_table/dos.pm
+++ b/perl-install/partition_table/dos.pm
@@ -236,10 +236,9 @@ sub read_one {
     [ @pt ];
 }
 
-# write the partition table (and extended ones)
-# for each entry, it uses fields: start, size, pt_type, active
-sub write {
-    my ($hd, $sector, $pt) = @_;
+# prepare to write the partition table (and extended ones)
+sub start_write {
+    my ($hd) = @_;
 
     log::l("partition::dos::write $hd->{device}");
 
@@ -250,6 +249,16 @@ sub write {
 	open $F, ">$file" or die "error opening test file $file";
     } else {
 	$F = partition_table::raw::openit($hd, 2) or die "error opening device $hd->{device} for writing";
+    }
+    $F;
+}
+
+# write the partition table (and extended ones)
+# for each entry, it uses fields: start, size, pt_type, active
+sub write {
+    my ($hd, $F, $sector, $pt) = @_;
+
+    if (!$::testing) {
         c::lseek_sector(fileno($F), $sector, $offset) or return 0;
     }
 
@@ -264,6 +273,11 @@ sub write {
     1;
 }
 
+sub end_write {
+    my ($hd, $F) = @_;
+    close $F;
+}
+
 sub empty_raw { { raw => [ ({}) x $nb_primary ] } }
 
 sub initialize { 
diff --git a/perl-install/partition_table/gpt.pm b/perl-install/partition_table/gpt.pm
index 3ac6673..df8ead3 100644
--- a/perl-install/partition_table/gpt.pm
+++ b/perl-install/partition_table/gpt.pm
@@ -71,7 +71,7 @@ sub read_one {
 }
 
 sub write {
-    my ($hd, $_sector, $pt, $_info) = @_;
+    my ($hd, $_handle, $_sector, $pt, $_info) = @_;
 
     my $partitions_killed;
 
diff --git a/perl-install/partition_table/mac.pm b/perl-install/partition_table/mac.pm
index 547704b..78e5469 100644
--- a/perl-install/partition_table/mac.pm
+++ b/perl-install/partition_table/mac.pm
@@ -193,7 +193,7 @@ sub read_one {
 }
 
 sub write($$$;$) {
-    my ($hd, $sector, $pt, $info) = @_;
+    my ($hd, $_handle, $sector, $pt, $info) = @_;
 
     #- handle testing for writing partition table on file only!
     my $F;
diff --git a/perl-install/partition_table/raw.pm b/perl-install/partition_table/raw.pm
index 7b4e7d5..e9b293b 100644
--- a/perl-install/partition_table/raw.pm
+++ b/perl-install/partition_table/raw.pm
@@ -295,4 +295,14 @@ A test to check the integrity of data has failed.
 It means writing anything on the disk will end up with random, corrupted data.");
 }
 
+sub start_write {
+    my ($_hd) = @_;
+    1;
+}
+
+sub end_write {
+    my ($_hd, $_handle) = @_;
+    1;
+}
+
 1;
diff --git a/perl-install/partition_table/sun.pm b/perl-install/partition_table/sun.pm
index e2fd747..e665d01 100644
--- a/perl-install/partition_table/sun.pm
+++ b/perl-install/partition_table/sun.pm
@@ -119,7 +119,7 @@ sub read_one {
 # write the partition table (and extended ones)
 # for each entry, it uses fields: start, size, pt_type, active
 sub write($$$;$) {
-    my ($hd, $sector, $pt, $info) = @_;
+    my ($hd, $_handle, $sector, $pt, $info) = @_;
 #    my ($csize, $wdsize) = (0, 0);
 
     #- handle testing for writing partition table on file only!
-- 
2.10.2

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Attachments on bug 20074: 8880 | 8881 | 8882 | 8883 | 8901 | 8906 | 8907 | 8908 | 8909 | 8926 | 8927 | 8972