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fs: protect inode->i_state with inode->i_lock

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Protect inode state transitions and validity checks with the
inode->i_lock. This enables us to make inode state transitions
independently of the inode_lock and is the first step to peeling
away the inode_lock from the code.

This requires that __iget() is done atomically with i_state checks
during list traversals so that we don't race with another thread
marking the inode I_FREEING between the state check and grabbing the
reference.

Also remove the unlock_new_inode() memory barrier optimisation
required to avoid taking the inode_lock when clearing I_NEW.
Simplify the code by simply taking the inode->i_lock around the
state change and wakeup. Because the wakeup is no longer tricky,
remove the wake_up_inode() function and open code the wakeup where
necessary.

Signed-off-by: Dave Chinner <[email protected]>
Signed-off-by: Al Viro <[email protected]>
This commit is contained in:
Dave Chinner 2011-03-22 22:23:36 +11:00 • committed by Al Viro
commit 250df6ed27
11 changed files with 174 additions and 74 deletions
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21
fs/notify/inode_mark.c
View file

@ -254,8 +254,11 @@ void fsnotify_unmount_inodes(struct list_head *list)
* I_WILL_FREE, or I_NEW which is fine because by that point
* the inode cannot have any associated watches.
*/
if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW))
spin_lock(&inode->i_lock);
if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) {
spin_unlock(&inode->i_lock);
continue;
}
/*
* If i_count is zero, the inode cannot have any watches and
@ -263,8 +266,10 @@ void fsnotify_unmount_inodes(struct list_head *list)
* evict all inodes with zero i_count from icache which is
* unnecessarily violent and may in fact be illegal to do.
*/
if (!atomic_read(&inode->i_count))
if (!atomic_read(&inode->i_count)) {
spin_unlock(&inode->i_lock);
continue;
}
need_iput_tmp = need_iput;
need_iput = NULL;
@ -274,13 +279,17 @@ void fsnotify_unmount_inodes(struct list_head *list)
__iget(inode);
else
need_iput_tmp = NULL;
spin_unlock(&inode->i_lock);
/* In case the dropping of a reference would nuke next_i. */
if ((&next_i->i_sb_list != list) &&
atomic_read(&next_i->i_count) &&
!(next_i->i_state & (I_FREEING | I_WILL_FREE))) {
__iget(next_i);
need_iput = next_i;
atomic_read(&next_i->i_count)) {
spin_lock(&next_i->i_lock);
if (!(next_i->i_state & (I_FREEING | I_WILL_FREE))) {
__iget(next_i);
need_iput = next_i;
}
spin_unlock(&next_i->i_lock);
}
/*