Commit 250df6ed authored by Dave Chinner's avatar Dave Chinner Committed by Al Viro

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

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: default avatarDave Chinner <dchinner@redhat.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 3dc8fe4d
......@@ -56,9 +56,11 @@ static void bdev_inode_switch_bdi(struct inode *inode,
struct backing_dev_info *dst)
{
spin_lock(&inode_lock);
spin_lock(&inode->i_lock);
inode->i_data.backing_dev_info = dst;
if (inode->i_state & I_DIRTY)
list_move(&inode->i_wb_list, &dst->wb.b_dirty);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
}
......
......@@ -1144,7 +1144,7 @@ __getblk_slow(struct block_device *bdev, sector_t block, int size)
* inode list.
*
* mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock,
* mapping->tree_lock and the global inode_lock.
* mapping->tree_lock and mapping->host->i_lock.
*/
void mark_buffer_dirty(struct buffer_head *bh)
{
......
......@@ -18,11 +18,14 @@ static void drop_pagecache_sb(struct super_block *sb, void *unused)
spin_lock(&inode_lock);
list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW))
continue;
if (inode->i_mapping->nrpages == 0)
spin_lock(&inode->i_lock);
if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
(inode->i_mapping->nrpages == 0)) {
spin_unlock(&inode->i_lock);
continue;
}
__iget(inode);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
invalidate_mapping_pages(inode->i_mapping, 0, -1);
iput(toput_inode);
......
......@@ -306,10 +306,12 @@ static void inode_wait_for_writeback(struct inode *inode)
wait_queue_head_t *wqh;
wqh = bit_waitqueue(&inode->i_state, __I_SYNC);
while (inode->i_state & I_SYNC) {
while (inode->i_state & I_SYNC) {
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
__wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE);
spin_lock(&inode_lock);
spin_lock(&inode->i_lock);
}
}
......@@ -333,6 +335,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
unsigned dirty;
int ret;
spin_lock(&inode->i_lock);
if (!atomic_read(&inode->i_count))
WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING)));
else
......@@ -348,6 +351,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
* completed a full scan of b_io.
*/
if (wbc->sync_mode != WB_SYNC_ALL) {
spin_unlock(&inode->i_lock);
requeue_io(inode);
return 0;
}
......@@ -363,6 +367,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
/* Set I_SYNC, reset I_DIRTY_PAGES */
inode->i_state |= I_SYNC;
inode->i_state &= ~I_DIRTY_PAGES;
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
ret = do_writepages(mapping, wbc);
......@@ -384,8 +389,10 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
* write_inode()
*/
spin_lock(&inode_lock);
spin_lock(&inode->i_lock);
dirty = inode->i_state & I_DIRTY;
inode->i_state &= ~(I_DIRTY_SYNC | I_DIRTY_DATASYNC);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
/* Don't write the inode if only I_DIRTY_PAGES was set */
if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) {
......@@ -395,6 +402,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
}
spin_lock(&inode_lock);
spin_lock(&inode->i_lock);
inode->i_state &= ~I_SYNC;
if (!(inode->i_state & I_FREEING)) {
if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
......@@ -436,6 +444,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
}
}
inode_sync_complete(inode);
spin_unlock(&inode->i_lock);
return ret;
}
......@@ -506,7 +515,9 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb,
* kind does not need peridic writeout yet, and for the latter
* kind writeout is handled by the freer.
*/
spin_lock(&inode->i_lock);
if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
spin_unlock(&inode->i_lock);
requeue_io(inode);
continue;
}
......@@ -515,10 +526,14 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb,
* Was this inode dirtied after sync_sb_inodes was called?
* This keeps sync from extra jobs and livelock.
*/
if (inode_dirtied_after(inode, wbc->wb_start))
if (inode_dirtied_after(inode, wbc->wb_start)) {
spin_unlock(&inode->i_lock);
return 1;
}
__iget(inode);
spin_unlock(&inode->i_lock);
pages_skipped = wbc->pages_skipped;
writeback_single_inode(inode, wbc);
if (wbc->pages_skipped != pages_skipped) {
......@@ -724,7 +739,9 @@ static long wb_writeback(struct bdi_writeback *wb,
if (!list_empty(&wb->b_more_io)) {
inode = wb_inode(wb->b_more_io.prev);
trace_wbc_writeback_wait(&wbc, wb->bdi);
spin_lock(&inode->i_lock);
inode_wait_for_writeback(inode);
spin_unlock(&inode->i_lock);
}
spin_unlock(&inode_lock);
}
......@@ -1017,6 +1034,7 @@ void __mark_inode_dirty(struct inode *inode, int flags)
block_dump___mark_inode_dirty(inode);
spin_lock(&inode_lock);
spin_lock(&inode->i_lock);
if ((inode->i_state & flags) != flags) {
const int was_dirty = inode->i_state & I_DIRTY;
......@@ -1028,7 +1046,7 @@ void __mark_inode_dirty(struct inode *inode, int flags)
* superblock list, based upon its state.
*/
if (inode->i_state & I_SYNC)
goto out;
goto out_unlock_inode;
/*
* Only add valid (hashed) inodes to the superblock's
......@@ -1036,11 +1054,12 @@ void __mark_inode_dirty(struct inode *inode, int flags)
*/
if (!S_ISBLK(inode->i_mode)) {
if (inode_unhashed(inode))
goto out;
goto out_unlock_inode;
}
if (inode->i_state & I_FREEING)
goto out;
goto out_unlock_inode;
spin_unlock(&inode->i_lock);
/*
* If the inode was already on b_dirty/b_io/b_more_io, don't
* reposition it (that would break b_dirty time-ordering).
......@@ -1065,7 +1084,10 @@ void __mark_inode_dirty(struct inode *inode, int flags)
inode->dirtied_when = jiffies;
list_move(&inode->i_wb_list, &bdi->wb.b_dirty);
}
goto out;
}
out_unlock_inode:
spin_unlock(&inode->i_lock);
out:
spin_unlock(&inode_lock);
......@@ -1111,14 +1133,16 @@ static void wait_sb_inodes(struct super_block *sb)
* we still have to wait for that writeout.
*/
list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
struct address_space *mapping;
struct address_space *mapping = inode->i_mapping;
if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW))
continue;
mapping = inode->i_mapping;
if (mapping->nrpages == 0)
spin_lock(&inode->i_lock);
if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
(mapping->nrpages == 0)) {
spin_unlock(&inode->i_lock);
continue;
}
__iget(inode);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
/*
* We hold a reference to 'inode' so it couldn't have
......
......@@ -27,6 +27,17 @@
#include <linux/ima.h>
#include <linux/cred.h>
/*
* inode locking rules.
*
* inode->i_lock protects:
* inode->i_state, inode->i_hash, __iget()
*
* Lock ordering:
* inode_lock
* inode->i_lock
*/
/*
* This is needed for the following functions:
* - inode_has_buffers
......@@ -137,15 +148,6 @@ int proc_nr_inodes(ctl_table *table, int write,
}
#endif
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_NEW);
}
/**
* inode_init_always - perform inode structure intialisation
* @sb: superblock inode belongs to
......@@ -336,7 +338,7 @@ static void init_once(void *foo)
}
/*
* inode_lock must be held
* inode->i_lock must be held
*/
void __iget(struct inode *inode)
{
......@@ -413,7 +415,9 @@ void __insert_inode_hash(struct inode *inode, unsigned long hashval)
struct hlist_head *b = inode_hashtable + hash(inode->i_sb, hashval);
spin_lock(&inode_lock);
spin_lock(&inode->i_lock);
hlist_add_head(&inode->i_hash, b);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
}
EXPORT_SYMBOL(__insert_inode_hash);
......@@ -438,7 +442,9 @@ static void __remove_inode_hash(struct inode *inode)
void remove_inode_hash(struct inode *inode)
{
spin_lock(&inode_lock);
spin_lock(&inode->i_lock);
hlist_del_init(&inode->i_hash);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
}
EXPORT_SYMBOL(remove_inode_hash);
......@@ -495,7 +501,9 @@ static void dispose_list(struct list_head *head)
__inode_sb_list_del(inode);
spin_unlock(&inode_lock);
wake_up_inode(inode);
spin_lock(&inode->i_lock);
wake_up_bit(&inode->i_state, __I_NEW);
spin_unlock(&inode->i_lock);
destroy_inode(inode);
}
}
......@@ -518,10 +526,17 @@ void evict_inodes(struct super_block *sb)
list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
if (atomic_read(&inode->i_count))
continue;
if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE))
spin_lock(&inode->i_lock);
if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
spin_unlock(&inode->i_lock);
continue;
}
inode->i_state |= I_FREEING;
if (!(inode->i_state & (I_DIRTY | I_SYNC)))
inodes_stat.nr_unused--;
spin_unlock(&inode->i_lock);
/*
* Move the inode off the IO lists and LRU once I_FREEING is
......@@ -529,8 +544,6 @@ void evict_inodes(struct super_block *sb)
*/
list_move(&inode->i_lru, &dispose);
list_del_init(&inode->i_wb_list);
if (!(inode->i_state & (I_DIRTY | I_SYNC)))
inodes_stat.nr_unused--;
}
spin_unlock(&inode_lock);
......@@ -563,18 +576,26 @@ int invalidate_inodes(struct super_block *sb, bool kill_dirty)
spin_lock(&inode_lock);
list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE))
spin_lock(&inode->i_lock);
if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
spin_unlock(&inode->i_lock);
continue;
}
if (inode->i_state & I_DIRTY && !kill_dirty) {
spin_unlock(&inode->i_lock);
busy = 1;
continue;
}
if (atomic_read(&inode->i_count)) {
spin_unlock(&inode->i_lock);
busy = 1;
continue;
}
inode->i_state |= I_FREEING;
if (!(inode->i_state & (I_DIRTY | I_SYNC)))
inodes_stat.nr_unused--;
spin_unlock(&inode->i_lock);
/*
* Move the inode off the IO lists and LRU once I_FREEING is
......@@ -582,8 +603,6 @@ int invalidate_inodes(struct super_block *sb, bool kill_dirty)
*/
list_move(&inode->i_lru, &dispose);
list_del_init(&inode->i_wb_list);
if (!(inode->i_state & (I_DIRTY | I_SYNC)))
inodes_stat.nr_unused--;
}
spin_unlock(&inode_lock);
......@@ -641,8 +660,10 @@ static void prune_icache(int nr_to_scan)
* Referenced or dirty inodes are still in use. Give them
* another pass through the LRU as we canot reclaim them now.
*/
spin_lock(&inode->i_lock);
if (atomic_read(&inode->i_count) ||
(inode->i_state & ~I_REFERENCED)) {
spin_unlock(&inode->i_lock);
list_del_init(&inode->i_lru);
inodes_stat.nr_unused--;
continue;
......@@ -650,12 +671,14 @@ static void prune_icache(int nr_to_scan)
/* recently referenced inodes get one more pass */
if (inode->i_state & I_REFERENCED) {
list_move(&inode->i_lru, &inode_lru);
inode->i_state &= ~I_REFERENCED;
spin_unlock(&inode->i_lock);
list_move(&inode->i_lru, &inode_lru);
continue;
}
if (inode_has_buffers(inode) || inode->i_data.nrpages) {
__iget(inode);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
if (remove_inode_buffers(inode))
reap += invalidate_mapping_pages(&inode->i_data,
......@@ -666,11 +689,15 @@ static void prune_icache(int nr_to_scan)
if (inode != list_entry(inode_lru.next,
struct inode, i_lru))
continue; /* wrong inode or list_empty */
if (!can_unuse(inode))
spin_lock(&inode->i_lock);
if (!can_unuse(inode)) {
spin_unlock(&inode->i_lock);
continue;
}
}
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
spin_unlock(&inode->i_lock);
/*
* Move the inode off the IO lists and LRU once I_FREEING is
......@@ -737,11 +764,13 @@ static struct inode *find_inode(struct super_block *sb,
continue;
if (!test(inode, data))
continue;
spin_lock(&inode->i_lock);
if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
__wait_on_freeing_inode(inode);
goto repeat;
}
__iget(inode);
spin_unlock(&inode->i_lock);
return inode;
}
return NULL;
......@@ -763,11 +792,13 @@ static struct inode *find_inode_fast(struct super_block *sb,
continue;
if (inode->i_sb != sb)
continue;
spin_lock(&inode->i_lock);
if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
__wait_on_freeing_inode(inode);
goto repeat;
}
__iget(inode);
spin_unlock(&inode->i_lock);
return inode;
}
return NULL;
......@@ -832,14 +863,23 @@ struct inode *new_inode(struct super_block *sb)
inode = alloc_inode(sb);
if (inode) {
spin_lock(&inode_lock);
__inode_sb_list_add(inode);
spin_lock(&inode->i_lock);
inode->i_state = 0;
spin_unlock(&inode->i_lock);
__inode_sb_list_add(inode);
spin_unlock(&inode_lock);
}
return inode;
}
EXPORT_SYMBOL(new_inode);
/**
* unlock_new_inode - clear the I_NEW state and wake up any waiters
* @inode: new inode to unlock
*
* Called when the inode is fully initialised to clear the new state of the
* inode and wake up anyone waiting for the inode to finish initialisation.
*/
void unlock_new_inode(struct inode *inode)
{
#ifdef CONFIG_DEBUG_LOCK_ALLOC
......@@ -859,19 +899,11 @@ void unlock_new_inode(struct inode *inode)
}
}
#endif
/*
* This is special! We do not need the spinlock when clearing I_NEW,
* because we're guaranteed that nobody else tries to do anything about
* the state of the inode when it is locked, as we just created it (so
* there can be no old holders that haven't tested I_NEW).
* However we must emit the memory barrier so that other CPUs reliably
* see the clearing of I_NEW after the other inode initialisation has
* completed.
*/
smp_mb();
spin_lock(&inode->i_lock);
WARN_ON(!(inode->i_state & I_NEW));
inode->i_state &= ~I_NEW;
wake_up_inode(inode);
wake_up_bit(&inode->i_state, __I_NEW);
spin_unlock(&inode->i_lock);
}
EXPORT_SYMBOL(unlock_new_inode);
......@@ -900,9 +932,11 @@ static struct inode *get_new_inode(struct super_block *sb,
if (set(inode, data))
goto set_failed;
spin_lock(&inode->i_lock);
inode->i_state = I_NEW;
hlist_add_head(&inode->i_hash, head);
spin_unlock(&inode->i_lock);
__inode_sb_list_add(inode);
inode->i_state = I_NEW;
spin_unlock(&inode_lock);
/* Return the locked inode with I_NEW set, the
......@@ -947,9 +981,11 @@ static struct inode *get_new_inode_fast(struct super_block *sb,
old = find_inode_fast(sb, head, ino);
if (!old) {
inode->i_ino = ino;
spin_lock(&inode->i_lock);
inode->i_state = I_NEW;
hlist_add_head(&inode->i_hash, head);
spin_unlock(&inode->i_lock);
__inode_sb_list_add(inode);
inode->i_state = I_NEW;
spin_unlock(&inode_lock);
/* Return the locked inode with I_NEW set, the
......@@ -1034,15 +1070,19 @@ EXPORT_SYMBOL(iunique);
struct inode *igrab(struct inode *inode)
{
spin_lock(&inode_lock);
if (!(inode->i_state & (I_FREEING|I_WILL_FREE)))
spin_lock(&inode->i_lock);
if (!(inode->i_state & (I_FREEING|I_WILL_FREE))) {
__iget(inode);
else
spin_unlock(&inode->i_lock);
} else {
spin_unlock(&inode->i_lock);
/*
* Handle the case where s_op->clear_inode is not been
* called yet, and somebody is calling igrab
* while the inode is getting freed.
*/
inode = NULL;
}
spin_unlock(&inode_lock);
return inode;
}
......@@ -1271,7 +1311,6 @@ int insert_inode_locked(struct inode *inode)
ino_t ino = inode->i_ino;
struct hlist_head *head = inode_hashtable + hash(sb, ino);
inode->i_state |= I_NEW;
while (1) {
struct hlist_node *node;
struct inode *old = NULL;
......@@ -1281,16 +1320,23 @@ int insert_inode_locked(struct inode *inode)
continue;
if (old->i_sb != sb)
continue;
if (old->i_state & (I_FREEING|I_WILL_FREE))
spin_lock(&old->i_lock);
if (old->i_state & (I_FREEING|I_WILL_FREE)) {
spin_unlock(&old->i_lock);
continue;
}
break;
}
if (likely(!node)) {
spin_lock(&inode->i_lock);
inode->i_state |= I_NEW;
hlist_add_head(&inode->i_hash, head);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
return 0;
}
__iget(old);
spin_unlock(&old->i_lock);
spin_unlock(&inode_lock);
wait_on_inode(old);
if (unlikely(!inode_unhashed(old))) {
......@@ -1308,8 +1354,6 @@ int insert_inode_locked4(struct inode *inode, unsigned long hashval,
struct super_block *sb = inode->i_sb;
struct hlist_head *head = inode_hashtable + hash(sb, hashval);
inode->i_state |= I_NEW;
while (1) {
struct hlist_node *node;
struct inode *old = NULL;
......@@ -1320,16 +1364,23 @@ int insert_inode_locked4(struct inode *inode, unsigned long hashval,
continue;
if (!test(old, data))
continue;
if (old->i_state & (I_FREEING|I_WILL_FREE))
spin_lock(&old->i_lock);
if (old->i_state & (I_FREEING|I_WILL_FREE)) {
spin_unlock(&old->i_lock);
continue;
}
break;
}
if (likely(!node)) {
spin_lock(&inode->i_lock);
inode->i_state |= I_NEW;
hlist_add_head(&inode->i_hash, head);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
return 0;
}
__iget(old);
spin_unlock(&old->i_lock);
spin_unlock(&inode_lock);
wait_on_inode(old);
if (unlikely(!inode_unhashed(old))) {
......@@ -1375,6 +1426,9 @@ static void iput_final(struct inode *inode)
const struct super_operations *op = inode->i_sb->s_op;
int drop;
spin_lock(&inode->i_lock);
WARN_ON(inode->i_state & I_NEW);
if (op && op->drop_inode)
drop = op->drop_inode(inode);
else
......@@ -1386,21 +1440,23 @@ static void iput_final(struct inode *inode)
if (!(inode->i_state & (I_DIRTY|I_SYNC))) {
inode_lru_list_add(inode);
}
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
return;
}
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_WILL_FREE;
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
write_inode_now(inode, 1);
spin_lock(&inode_lock);
spin_lock(&inode->i_lock);
WARN_ON(inode->i_state & I_NEW);
inode->i_state &= ~I_WILL_FREE;
__remove_inode_hash(inode);
}
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
spin_unlock(&inode->i_lock);
/*
* Move the inode off the IO lists and LRU once I_FREEING is
......@@ -1413,8 +1469,10 @@ static void iput_final(struct inode *inode)
spin_unlock(&inode_lock);
evict(inode);
remove_inode_hash(inode);
wake_up_inode(inode);
spin_lock(&inode->i_lock);
wake_up_bit(&inode->i_state, __I_NEW);
BUG_ON(inode->i_state != (I_FREEING | I_CLEAR));
spin_unlock(&inode->i_lock);
destroy_inode(inode);
}
......@@ -1611,9 +1669,8 @@ EXPORT_SYMBOL(inode_wait);
* to recheck inode state.
*
* It doesn't matter if I_NEW is not set initially, a call to
* wake_up_inode() after removing from the hash list will DTRT.
*
* This is called with inode_lock held.
* wake_up_bit(&inode->i_state, __I_NEW) after removing from the hash list
* will DTRT.
*/
static void __wait_on_freeing_inode(struct inode *inode)
{
......@@ -1621,6 +1678,7 @@ static void __wait_on_freeing_inode(struct inode *inode)
DEFINE_WAIT_BIT(wait, &inode->i_state, __I_NEW);
wq = bit_waitqueue(&inode->i_state, __I_NEW);
prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
schedule();
finish_wait(wq, &wait.wait);
......
......@@ -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)) {