introduce I_SYNC
I_LOCK was used for several unrelated purposes, which caused deadlock
situations in certain filesystems as a side effect. One of the purposes
now uses the new I_SYNC bit.
Also document the various bits and change their order from historical to
logical.
[bunk@stusta.de: make fs/inode.c:wake_up_inode() static]
Signed-off-by: Joern Engel <joern@wohnheim.fh-wedel.de>
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: David Chinner <dgc@sgi.com>
Cc: Anton Altaparmakov <aia21@cam.ac.uk>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 71c158a..686734f 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -100,11 +100,11 @@
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 @@
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 @@
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 @@
}
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 @@
list_move(&inode->i_list, &inode_unused);
}
}
- wake_up_inode(inode);
+ inode_sync_complete(inode);
return ret;
}
@@ -324,7 +333,7 @@
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 @@
/*
* 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 @@
* 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 @@
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 @@
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 6bf6890..0f5df73 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -384,7 +384,7 @@
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 c616577..ed35383 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -99,6 +99,15 @@
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 @@
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 @@
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 @@
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 @@
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 7aa1f70..e7c60ae 100644
--- a/fs/jfs/jfs_txnmgr.c
+++ b/fs/jfs/jfs_txnmgr.c
@@ -1289,7 +1289,14 @@
* 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 0b5fa12..e0e06dd 100644
--- a/fs/xfs/linux-2.6/xfs_iops.c
+++ b/fs/xfs/linux-2.6/xfs_iops.c
@@ -133,7 +133,7 @@
*/
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 @@
*/
SYNCHRONIZE();
ip->i_update_core = 1;
- if (!(inode->i_state & I_LOCK))
+ if (!(inode->i_state & I_SYNC))
mark_inode_dirty_sync(inode);
}