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Explicitly pass in whether sb is pinned or not 

fix famous Kees Cook bug,
patches are scheduled for 2.6.35-rc1 and will go into stable.
this is the first that fixes original issue.

svn path=/dists/trunk/linux-2.6/; revision=15747
This commit is contained in:
Maximilian Attems 2010-05-18 14:24:31 +00:00
parent 1567b0b483
commit e61f224150
3 changed files with 198 additions and 0 deletions
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1
debian/changelog vendored
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@ -20,6 +20,7 @@ linux-2.6 (2.6.34-1~experimental.1) UNRELEASED; urgency=low
* Fix backlight support on some recent Thinkpads.
* Enable autosuspend on UVC by default.
* acpi: Fall back to manually changing SCI_EN.
* Explicitly pass in whether sb is pinned or not.
[ Ben Hutchings ]
* Prepare debconf templates for translation (Closes: #576758)

196
debian/patches/bugfix/all/fs-explicitly-pass-in-whether-sb-is-pinned-or-not.patch vendored Normal file
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@ -0,0 +1,196 @@
From: Jens Axboe <axboe@kernel.dk>
Date: 2010-05-06 07:08:55
Subject: Explicitly pass in whether sb is pinned or not
Revision two of this patch. I got rid of WB_SYNC_NONE_PIN, since we should not
further muddy the sync type and whether or not the sb is pinned. Instead lets
add a specific flag for this.
BZ: 15906, Launchpad: 543617
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 4b37f7c..c9ac9cb 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -45,6 +45,7 @@ struct wb_writeback_args {
int for_kupdate:1;
int range_cyclic:1;
int for_background:1;
+ int sb_pinned:1;
};
/*
@@ -230,6 +231,11 @@ static void bdi_sync_writeback(struct backing_dev_info *bdi,
.sync_mode = WB_SYNC_ALL,
.nr_pages = LONG_MAX,
.range_cyclic = 0,
+ /*
+ * Setting sb_pinned is not necessary for WB_SYNC_ALL, but
+ * lets make it explicitly clear.
+ */
+ .sb_pinned = 1,
};
struct bdi_work work;
@@ -245,21 +251,23 @@ static void bdi_sync_writeback(struct backing_dev_info *bdi,
* @bdi: the backing device to write from
* @sb: write inodes from this super_block
* @nr_pages: the number of pages to write
+ * @sb_locked: caller already holds sb umount sem.
*
* Description:
* This does WB_SYNC_NONE opportunistic writeback. The IO is only
* started when this function returns, we make no guarentees on
- * completion. Caller need not hold sb s_umount semaphore.
+ * completion. Caller specifies whether sb umount sem is held already or not.
*
*/
void bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
- long nr_pages)
+ long nr_pages, int sb_locked)
{
struct wb_writeback_args args = {
.sb = sb,
.sync_mode = WB_SYNC_NONE,
.nr_pages = nr_pages,
.range_cyclic = 1,
+ .sb_pinned = sb_locked,
};
/*
@@ -577,7 +585,7 @@ static enum sb_pin_state pin_sb_for_writeback(struct writeback_control *wbc,
/*
* Caller must already hold the ref for this
*/
- if (wbc->sync_mode == WB_SYNC_ALL) {
+ if (wbc->sync_mode == WB_SYNC_ALL || wbc->sb_pinned) {
WARN_ON(!rwsem_is_locked(&sb->s_umount));
return SB_NOT_PINNED;
}
@@ -751,6 +759,7 @@ static long wb_writeback(struct bdi_writeback *wb,
.for_kupdate = args->for_kupdate,
.for_background = args->for_background,
.range_cyclic = args->range_cyclic,
+ .sb_pinned = args->sb_pinned,
};
unsigned long oldest_jif;
long wrote = 0;
@@ -1183,6 +1192,18 @@ static void wait_sb_inodes(struct super_block *sb)
iput(old_inode);
}
+static void __writeback_inodes_sb(struct super_block *sb, int sb_locked)
+{
+ unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY);
+ unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS);
+ long nr_to_write;
+
+ nr_to_write = nr_dirty + nr_unstable +
+ (inodes_stat.nr_inodes - inodes_stat.nr_unused);
+
+ bdi_start_writeback(sb->s_bdi, sb, nr_to_write, sb_locked);
+}
+
/**
* writeback_inodes_sb - writeback dirty inodes from given super_block
* @sb: the superblock
@@ -1194,18 +1215,23 @@ static void wait_sb_inodes(struct super_block *sb)
*/
void writeback_inodes_sb(struct super_block *sb)
{
- unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY);
- unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS);
- long nr_to_write;
-
- nr_to_write = nr_dirty + nr_unstable +
- (inodes_stat.nr_inodes - inodes_stat.nr_unused);
-
- bdi_start_writeback(sb->s_bdi, sb, nr_to_write);
+ __writeback_inodes_sb(sb, 0);
}
EXPORT_SYMBOL(writeback_inodes_sb);
/**
+ * writeback_inodes_sb_locked - writeback dirty inodes from given super_block
+ * @sb: the superblock
+ *
+ * Like writeback_inodes_sb(), except the caller already holds the
+ * sb umount sem.
+ */
+void writeback_inodes_sb_locked(struct super_block *sb)
+{
+ __writeback_inodes_sb(sb, 1);
+}
+
+/**
* writeback_inodes_sb_if_idle - start writeback if none underway
* @sb: the superblock
*
diff --git a/fs/sync.c b/fs/sync.c
index 92b2281..de6a441 100644
--- a/fs/sync.c
+++ b/fs/sync.c
@@ -42,7 +42,7 @@ static int __sync_filesystem(struct super_block *sb, int wait)
if (wait)
sync_inodes_sb(sb);
else
- writeback_inodes_sb(sb);
+ writeback_inodes_sb_locked(sb);
if (sb->s_op->sync_fs)
sb->s_op->sync_fs(sb, wait);
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index bd0e3c6..90e677a 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -103,7 +103,7 @@ int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
void bdi_unregister(struct backing_dev_info *bdi);
int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int);
void bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
- long nr_pages);
+ long nr_pages, int sb_locked);
int bdi_writeback_task(struct bdi_writeback *wb);
int bdi_has_dirty_io(struct backing_dev_info *bdi);
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 36520de..3790165 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -65,6 +65,15 @@ struct writeback_control {
* so we use a single control to update them
*/
unsigned no_nrwrite_index_update:1;
+
+ /*
+ * For WB_SYNC_ALL, the sb must always be pinned. For WB_SYNC_NONE,
+ * the writeback code will pin the sb for the caller. However,
+ * for eg umount, the caller does WB_SYNC_NONE but already has
+ * the sb pinned. If the below is set, caller already has the
+ * sb pinned.
+ */
+ unsigned sb_pinned:1;
};
/*
@@ -73,6 +82,7 @@ struct writeback_control {
struct bdi_writeback;
int inode_wait(void *);
void writeback_inodes_sb(struct super_block *);
+void writeback_inodes_sb_locked(struct super_block *);
int writeback_inodes_sb_if_idle(struct super_block *);
void sync_inodes_sb(struct super_block *);
void writeback_inodes_wbc(struct writeback_control *wbc);
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 0b19943..49d3508 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -597,7 +597,7 @@ static void balance_dirty_pages(struct address_space *mapping,
(!laptop_mode && ((global_page_state(NR_FILE_DIRTY)
+ global_page_state(NR_UNSTABLE_NFS))
> background_thresh)))
- bdi_start_writeback(bdi, NULL, 0);
+ bdi_start_writeback(bdi, NULL, 0, 0);
}
void set_page_dirty_balance(struct page *page, int page_mkwrite)

1
debian/patches/series/base vendored
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@ -68,3 +68,4 @@
+ bugfix/all/thinkpad-acpi-fix-backlight.patch
+ bugfix/all/linux-2.6-usb-uvc-autosuspend.diff
+ bugfix/all/linux-2.6-acpi-sleep-live-sci-live.patch
+ bugfix/all/fs-explicitly-pass-in-whether-sb-is-pinned-or-not.patch