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-rw-r--r--fs/fs-writeback.c39
-rw-r--r--fs/hugetlbfs/inode.c2
-rw-r--r--fs/inode.c24
-rw-r--r--fs/jfs/jfs_txnmgr.c9
-rw-r--r--fs/xfs/linux-2.6/xfs_iops.c4
-rw-r--r--include/linux/fs.h70
-rw-r--r--include/linux/writeback.h8
-rw-r--r--mm/page-writeback.c2
8 files changed, 116 insertions, 42 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 71c158ac60a..686734ff973 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -100,11 +100,11 @@ void __mark_inode_dirty(struct inode *inode, int flags)
inode->i_state |= flags;
/*
- * If the inode is locked, just update its dirty state.
+ * If the inode is being synced, just update its dirty state.
* The unlocker will place the inode on the appropriate
* superblock list, based upon its state.
*/
- if (inode->i_state & I_LOCK)
+ if (inode->i_state & I_SYNC)
goto out;
/*
@@ -172,6 +172,15 @@ static void requeue_io(struct inode *inode)
list_move(&inode->i_list, &inode->i_sb->s_more_io);
}
+static void inode_sync_complete(struct inode *inode)
+{
+ /*
+ * Prevent speculative execution through spin_unlock(&inode_lock);
+ */
+ smp_mb();
+ wake_up_bit(&inode->i_state, __I_SYNC);
+}
+
/*
* Move expired dirty inodes from @delaying_queue to @dispatch_queue.
*/
@@ -225,11 +234,11 @@ __sync_single_inode(struct inode *inode, struct writeback_control *wbc)
int wait = wbc->sync_mode == WB_SYNC_ALL;
int ret;
- BUG_ON(inode->i_state & I_LOCK);
+ BUG_ON(inode->i_state & I_SYNC);
- /* Set I_LOCK, reset I_DIRTY */
+ /* Set I_SYNC, reset I_DIRTY */
dirty = inode->i_state & I_DIRTY;
- inode->i_state |= I_LOCK;
+ inode->i_state |= I_SYNC;
inode->i_state &= ~I_DIRTY;
spin_unlock(&inode_lock);
@@ -250,7 +259,7 @@ __sync_single_inode(struct inode *inode, struct writeback_control *wbc)
}
spin_lock(&inode_lock);
- inode->i_state &= ~I_LOCK;
+ inode->i_state &= ~I_SYNC;
if (!(inode->i_state & I_FREEING)) {
if (!(inode->i_state & I_DIRTY) &&
mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
@@ -305,7 +314,7 @@ __sync_single_inode(struct inode *inode, struct writeback_control *wbc)
list_move(&inode->i_list, &inode_unused);
}
}
- wake_up_inode(inode);
+ inode_sync_complete(inode);
return ret;
}
@@ -324,7 +333,7 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
else
WARN_ON(inode->i_state & I_WILL_FREE);
- if ((wbc->sync_mode != WB_SYNC_ALL) && (inode->i_state & I_LOCK)) {
+ if ((wbc->sync_mode != WB_SYNC_ALL) && (inode->i_state & I_SYNC)) {
struct address_space *mapping = inode->i_mapping;
int ret;
@@ -350,16 +359,16 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
/*
* It's a data-integrity sync. We must wait.
*/
- if (inode->i_state & I_LOCK) {
- DEFINE_WAIT_BIT(wq, &inode->i_state, __I_LOCK);
+ if (inode->i_state & I_SYNC) {
+ DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC);
- wqh = bit_waitqueue(&inode->i_state, __I_LOCK);
+ wqh = bit_waitqueue(&inode->i_state, __I_SYNC);
do {
spin_unlock(&inode_lock);
__wait_on_bit(wqh, &wq, inode_wait,
TASK_UNINTERRUPTIBLE);
spin_lock(&inode_lock);
- } while (inode->i_state & I_LOCK);
+ } while (inode->i_state & I_SYNC);
}
return __sync_single_inode(inode, wbc);
}
@@ -392,7 +401,7 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
* The inodes to be written are parked on sb->s_io. They are moved back onto
* sb->s_dirty as they are selected for writing. This way, none can be missed
* on the writer throttling path, and we get decent balancing between many
- * throttled threads: we don't want them all piling up on __wait_on_inode.
+ * throttled threads: we don't want them all piling up on inode_sync_wait.
*/
static void
sync_sb_inodes(struct super_block *sb, struct writeback_control *wbc)
@@ -661,7 +670,7 @@ int write_inode_now(struct inode *inode, int sync)
ret = __writeback_single_inode(inode, &wbc);
spin_unlock(&inode_lock);
if (sync)
- wait_on_inode(inode);
+ inode_sync_wait(inode);
return ret;
}
EXPORT_SYMBOL(write_inode_now);
@@ -736,7 +745,7 @@ int generic_osync_inode(struct inode *inode, struct address_space *mapping, int
err = err2;
}
else
- wait_on_inode(inode);
+ inode_sync_wait(inode);
return err;
}
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 6bf6890f053..0f5df73dbb7 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -384,7 +384,7 @@ static void hugetlbfs_forget_inode(struct inode *inode) __releases(inode_lock)
struct super_block *sb = inode->i_sb;
if (!hlist_unhashed(&inode->i_hash)) {
- if (!(inode->i_state & (I_DIRTY|I_LOCK)))
+ if (!(inode->i_state & (I_DIRTY|I_SYNC)))
list_move(&inode->i_list, &inode_unused);
inodes_stat.nr_unused++;
if (!sb || (sb->s_flags & MS_ACTIVE)) {
diff --git a/fs/inode.c b/fs/inode.c
index c6165771e00..ed35383d0b6 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -99,6 +99,15 @@ struct inodes_stat_t inodes_stat;
static struct kmem_cache * inode_cachep __read_mostly;
+static void wake_up_inode(struct inode *inode)
+{
+ /*
+ * Prevent speculative execution through spin_unlock(&inode_lock);
+ */
+ smp_mb();
+ wake_up_bit(&inode->i_state, __I_LOCK);
+}
+
static struct inode *alloc_inode(struct super_block *sb)
{
static const struct address_space_operations empty_aops;
@@ -232,7 +241,7 @@ void __iget(struct inode * inode)
return;
}
atomic_inc(&inode->i_count);
- if (!(inode->i_state & (I_DIRTY|I_LOCK)))
+ if (!(inode->i_state & (I_DIRTY|I_SYNC)))
list_move(&inode->i_list, &inode_in_use);
inodes_stat.nr_unused--;
}
@@ -253,7 +262,7 @@ void clear_inode(struct inode *inode)
BUG_ON(inode->i_data.nrpages);
BUG_ON(!(inode->i_state & I_FREEING));
BUG_ON(inode->i_state & I_CLEAR);
- wait_on_inode(inode);
+ inode_sync_wait(inode);
DQUOT_DROP(inode);
if (inode->i_sb->s_op->clear_inode)
inode->i_sb->s_op->clear_inode(inode);
@@ -1071,7 +1080,7 @@ static void generic_forget_inode(struct inode *inode)
struct super_block *sb = inode->i_sb;
if (!hlist_unhashed(&inode->i_hash)) {
- if (!(inode->i_state & (I_DIRTY|I_LOCK)))
+ if (!(inode->i_state & (I_DIRTY|I_SYNC)))
list_move(&inode->i_list, &inode_unused);
inodes_stat.nr_unused++;
if (sb->s_flags & MS_ACTIVE) {
@@ -1314,15 +1323,6 @@ static void __wait_on_freeing_inode(struct inode *inode)
spin_lock(&inode_lock);
}
-void wake_up_inode(struct inode *inode)
-{
- /*
- * Prevent speculative execution through spin_unlock(&inode_lock);
- */
- smp_mb();
- wake_up_bit(&inode->i_state, __I_LOCK);
-}
-
/*
* We rarely want to lock two inodes that do not have a parent/child
* relationship (such as directory, child inode) simultaneously. The
diff --git a/fs/jfs/jfs_txnmgr.c b/fs/jfs/jfs_txnmgr.c
index 7aa1f7004ea..e7c60ae6b5b 100644
--- a/fs/jfs/jfs_txnmgr.c
+++ b/fs/jfs/jfs_txnmgr.c
@@ -1289,7 +1289,14 @@ int txCommit(tid_t tid, /* transaction identifier */
* commit the transaction synchronously, so the last iput
* will be done by the calling thread (or later)
*/
- if (tblk->u.ip->i_state & I_LOCK)
+ /*
+ * I believe this code is no longer needed. Splitting I_LOCK
+ * into two bits, I_LOCK and I_SYNC should prevent this
+ * deadlock as well. But since I don't have a JFS testload
+ * to verify this, only a trivial s/I_LOCK/I_SYNC/ was done.
+ * Joern
+ */
+ if (tblk->u.ip->i_state & I_SYNC)
tblk->xflag &= ~COMMIT_LAZY;
}
diff --git a/fs/xfs/linux-2.6/xfs_iops.c b/fs/xfs/linux-2.6/xfs_iops.c
index 0b5fa124bef..e0e06dd4bef 100644
--- a/fs/xfs/linux-2.6/xfs_iops.c
+++ b/fs/xfs/linux-2.6/xfs_iops.c
@@ -133,7 +133,7 @@ xfs_ichgtime(
*/
SYNCHRONIZE();
ip->i_update_core = 1;
- if (!(inode->i_state & I_LOCK))
+ if (!(inode->i_state & I_SYNC))
mark_inode_dirty_sync(inode);
}
@@ -185,7 +185,7 @@ xfs_ichgtime_fast(
*/
SYNCHRONIZE();
ip->i_update_core = 1;
- if (!(inode->i_state & I_LOCK))
+ if (!(inode->i_state & I_SYNC))
mark_inode_dirty_sync(inode);
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index b70331f9f5b..365586a4c4d 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1261,16 +1261,68 @@ struct super_operations {
#endif
};
-/* Inode state bits. Protected by inode_lock. */
-#define I_DIRTY_SYNC 1 /* Not dirty enough for O_DATASYNC */
-#define I_DIRTY_DATASYNC 2 /* Data-related inode changes pending */
-#define I_DIRTY_PAGES 4 /* Data-related inode changes pending */
-#define __I_LOCK 3
+/*
+ * Inode state bits. Protected by inode_lock.
+ *
+ * Three bits determine the dirty state of the inode, I_DIRTY_SYNC,
+ * I_DIRTY_DATASYNC and I_DIRTY_PAGES.
+ *
+ * Four bits define the lifetime of an inode. Initially, inodes are I_NEW,
+ * until that flag is cleared. I_WILL_FREE, I_FREEING and I_CLEAR are set at
+ * various stages of removing an inode.
+ *
+ * Two bits are used for locking and completion notification, I_LOCK and I_SYNC.
+ *
+ * I_DIRTY_SYNC Inode itself is dirty.
+ * I_DIRTY_DATASYNC Data-related inode changes pending
+ * I_DIRTY_PAGES Inode has dirty pages. Inode itself may be clean.
+ * I_NEW get_new_inode() sets i_state to I_LOCK|I_NEW. Both
+ * are cleared by unlock_new_inode(), called from iget().
+ * I_WILL_FREE Must be set when calling write_inode_now() if i_count
+ * is zero. I_FREEING must be set when I_WILL_FREE is
+ * cleared.
+ * I_FREEING Set when inode is about to be freed but still has dirty
+ * pages or buffers attached or the inode itself is still
+ * dirty.
+ * I_CLEAR Set by clear_inode(). In this state the inode is clean
+ * and can be destroyed.
+ *
+ * Inodes that are I_WILL_FREE, I_FREEING or I_CLEAR are
+ * prohibited for many purposes. iget() must wait for
+ * the inode to be completely released, then create it
+ * anew. Other functions will just ignore such inodes,
+ * if appropriate. I_LOCK is used for waiting.
+ *
+ * I_LOCK Serves as both a mutex and completion notification.
+ * New inodes set I_LOCK. If two processes both create
+ * the same inode, one of them will release its inode and
+ * wait for I_LOCK to be released before returning.
+ * Inodes in I_WILL_FREE, I_FREEING or I_CLEAR state can
+ * also cause waiting on I_LOCK, without I_LOCK actually
+ * being set. find_inode() uses this to prevent returning
+ * nearly-dead inodes.
+ * I_SYNC Similar to I_LOCK, but limited in scope to writeback
+ * of inode dirty data. Having a seperate lock for this
+ * purpose reduces latency and prevents some filesystem-
+ * specific deadlocks.
+ *
+ * Q: Why does I_DIRTY_DATASYNC exist? It appears as if it could be replaced
+ * by (I_DIRTY_SYNC|I_DIRTY_PAGES).
+ * Q: What is the difference between I_WILL_FREE and I_FREEING?
+ * Q: igrab() only checks on (I_FREEING|I_WILL_FREE). Should it also check on
+ * I_CLEAR? If not, why?
+ */
+#define I_DIRTY_SYNC 1
+#define I_DIRTY_DATASYNC 2
+#define I_DIRTY_PAGES 4
+#define I_NEW 8
+#define I_WILL_FREE 16
+#define I_FREEING 32
+#define I_CLEAR 64
+#define __I_LOCK 7
#define I_LOCK (1 << __I_LOCK)
-#define I_FREEING 16
-#define I_CLEAR 32
-#define I_NEW 64
-#define I_WILL_FREE 128
+#define __I_SYNC 8
+#define I_SYNC (1 << __I_SYNC)
#define I_DIRTY (I_DIRTY_SYNC | I_DIRTY_DATASYNC | I_DIRTY_PAGES)
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 1200868a5de..bef7d66601c 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -69,7 +69,6 @@ struct writeback_control {
* fs/fs-writeback.c
*/
void writeback_inodes(struct writeback_control *wbc);
-void wake_up_inode(struct inode *inode);
int inode_wait(void *);
void sync_inodes_sb(struct super_block *, int wait);
void sync_inodes(int wait);
@@ -81,6 +80,13 @@ static inline void wait_on_inode(struct inode *inode)
wait_on_bit(&inode->i_state, __I_LOCK, inode_wait,
TASK_UNINTERRUPTIBLE);
}
+static inline void inode_sync_wait(struct inode *inode)
+{
+ might_sleep();
+ wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
+ TASK_UNINTERRUPTIBLE);
+}
+
/*
* mm/page-writeback.c
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index bcdbbf6c4a8..d8c21e5a1bc 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -37,7 +37,7 @@
/*
* The maximum number of pages to writeout in a single bdflush/kupdate
- * operation. We do this so we don't hold I_LOCK against an inode for
+ * operation. We do this so we don't hold I_SYNC against an inode for
* enormous amounts of time, which would block a userspace task which has
* been forced to throttle against that inode. Also, the code reevaluates
* the dirty each time it has written this many pages.
generated by cgit v1.2.3 (git 2.25.1) at 2024-05-14 16:49:54 +0000