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Message-ID: <5162EEDB.2050102@gmail.com>
Date: Mon, 08 Apr 2013 18:22:51 +0200
From: Marco Stornelli <marco.stornelli@...il.com>
To: Linux FS Devel <linux-fsdevel@...r.kernel.org>
CC: Linux Kernel <linux-kernel@...r.kernel.org>,
Al Viro <viro@...IV.linux.org.uk>, Jan Kara <jack@...e.cz>
Subject: [PATCH 1/2 v 2][RFC] fsfreeze: add new internal __sb_start_write_wait
Added a new internal function __sb_start_write_wait. It must be called
when we want wait for freeze events. We can wait in killable or
uninterruptible state. The old __sb_start_write now it's used only
when we don't want to wait. In addition, a new wrapper sb_start_write_killable
is added.
Signed-off-by: Marco Stornelli <marco.stornelli@...il.com>
---
fs/super.c | 47 ++++++++++++++++++++++++++++++++++++++++-------
include/linux/fs.h | 23 ++++++++++++++++++-----
2 files changed, 58 insertions(+), 12 deletions(-)
diff --git a/fs/super.c b/fs/super.c
index 7465d43..cb0149b 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -1190,15 +1190,11 @@ static void acquire_freeze_lock(struct super_block *sb, int level, bool trylock,
* This is an internal function, please use sb_start_{write,pagefault,intwrite}
* instead.
*/
-int __sb_start_write(struct super_block *sb, int level, bool wait)
+int __sb_start_write(struct super_block *sb, int level)
{
retry:
- if (unlikely(sb->s_writers.frozen >= level)) {
- if (!wait)
- return 0;
- wait_event(sb->s_writers.wait_unfrozen,
- sb->s_writers.frozen < level);
- }
+ if (unlikely(sb->s_writers.frozen >= level))
+ return 0;
#ifdef CONFIG_LOCKDEP
acquire_freeze_lock(sb, level, !wait, _RET_IP_);
@@ -1217,6 +1213,43 @@ retry:
}
EXPORT_SYMBOL(__sb_start_write);
+/*
+ * This is an internal function, please use sb_start_{write,pagefault,intwrite}
+ * instead. It returns zero if no error occured, the error code otherwise.
+ */
+int __sb_start_write_wait(struct super_block *sb, int level, bool wait_killable)
+{
+ int ret = 0;
+
+retry:
+ if (unlikely(sb->s_writers.frozen >= level)) {
+ if (wait_killable)
+ ret = wait_event_killable(sb->s_writers.wait_unfrozen,
+ sb->s_writers.frozen < level);
+ if (ret)
+ return -EINTR;
+ else
+ wait_event(sb->s_writers.wait_unfrozen,
+ sb->s_writers.frozen < level);
+ }
+
+#ifdef CONFIG_LOCKDEP
+ acquire_freeze_lock(sb, level, !wait, _RET_IP_);
+#endif
+ percpu_counter_inc(&sb->s_writers.counter[level-1]);
+ /*
+ * Make sure counter is updated before we check for frozen.
+ * freeze_super() first sets frozen and then checks the counter.
+ */
+ smp_mb();
+ if (unlikely(sb->s_writers.frozen >= level)) {
+ __sb_end_write(sb, level);
+ goto retry;
+ }
+ return ret;
+}
+EXPORT_SYMBOL(__sb_start_write_wait);
+
/**
* sb_wait_write - wait until all writers to given file system finish
* @sb: the super for which we wait
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 2c28271..6428dbd 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1333,7 +1333,8 @@ extern struct timespec current_fs_time(struct super_block *sb);
*/
void __sb_end_write(struct super_block *sb, int level);
-int __sb_start_write(struct super_block *sb, int level, bool wait);
+int __sb_start_write(struct super_block *sb, int level);
+int __sb_start_write_wait(struct super_block *sb, int level, bool wait_killable);
/**
* sb_end_write - drop write access to a superblock
@@ -1392,12 +1393,24 @@ static inline void sb_end_intwrite(struct super_block *sb)
*/
static inline void sb_start_write(struct super_block *sb)
{
- __sb_start_write(sb, SB_FREEZE_WRITE, true);
+ __sb_start_write_wait(sb, SB_FREEZE_WRITE, false);
+}
+
+/**
+ * sb_start_write_killable - get write access to a superblock
+ * @sb: the super we write to
+ *
+ * Same semantic of sb_start_write, but we are going to wait in a killable
+ * state instead of waiting in uninterruptible state.
+ */
+static inline int __must_check sb_start_write_killable(struct super_block *sb)
+{
+ return __sb_start_write_wait(sb, SB_FREEZE_WRITE, true);
}
static inline int sb_start_write_trylock(struct super_block *sb)
{
- return __sb_start_write(sb, SB_FREEZE_WRITE, false);
+ return __sb_start_write(sb, SB_FREEZE_WRITE);
}
/**
@@ -1421,7 +1434,7 @@ static inline int sb_start_write_trylock(struct super_block *sb)
*/
static inline void sb_start_pagefault(struct super_block *sb)
{
- __sb_start_write(sb, SB_FREEZE_PAGEFAULT, true);
+ __sb_start_write_wait(sb, SB_FREEZE_PAGEFAULT, false);
}
/*
@@ -1439,7 +1452,7 @@ static inline void sb_start_pagefault(struct super_block *sb)
*/
static inline void sb_start_intwrite(struct super_block *sb)
{
- __sb_start_write(sb, SB_FREEZE_FS, true);
+ __sb_start_write_wait(sb, SB_FREEZE_FS, false);
}
--
1.7.3.4
--
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