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Merge branch 'work.dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

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Pull dcache updates from Al Viro:
 "Neil Brown's d_move()/d_path() race fix"

* 'work.dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  VFS: close race between getcwd() and d_move()
This commit is contained in:
Linus Torvalds 2018-01-31 19:15:23 -08:00
commit dc1efc3cfa
1 changed files with 16 additions and 7 deletions
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23
fs/dcache.c
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@ -466,9 +466,11 @@ static void dentry_lru_add(struct dentry *dentry)
* d_drop() is used mainly for stuff that wants to invalidate a dentry for some
* reason (NFS timeouts or autofs deletes).
*
* __d_drop requires dentry->d_lock.
* __d_drop requires dentry->d_lock
* ___d_drop doesn't mark dentry as "unhashed"
* (dentry->d_hash.pprev will be LIST_POISON2, not NULL).
*/
void __d_drop(struct dentry *dentry)
static void ___d_drop(struct dentry *dentry)
{
if (!d_unhashed(dentry)) {
struct hlist_bl_head *b;
@ -484,12 +486,17 @@ void __d_drop(struct dentry *dentry)
hlist_bl_lock(b);
__hlist_bl_del(&dentry->d_hash);
dentry->d_hash.pprev = NULL;
hlist_bl_unlock(b);
/* After this call, in-progress rcu-walk path lookup will fail. */
write_seqcount_invalidate(&dentry->d_seq);
}
}
void __d_drop(struct dentry *dentry)
{
___d_drop(dentry);
dentry->d_hash.pprev = NULL;
}
EXPORT_SYMBOL(__d_drop);
void d_drop(struct dentry *dentry)
@ -2380,7 +2387,7 @@ EXPORT_SYMBOL(d_delete);
static void __d_rehash(struct dentry *entry)
{
struct hlist_bl_head *b = d_hash(entry->d_name.hash);
BUG_ON(!d_unhashed(entry));
hlist_bl_lock(b);
hlist_bl_add_head_rcu(&entry->d_hash, b);
hlist_bl_unlock(b);
@ -2815,9 +2822,9 @@ static void __d_move(struct dentry *dentry, struct dentry *target,
write_seqcount_begin_nested(&target->d_seq, DENTRY_D_LOCK_NESTED);
/* unhash both */
/* __d_drop does write_seqcount_barrier, but they're OK to nest. */
__d_drop(dentry);
__d_drop(target);
/* ___d_drop does write_seqcount_barrier, but they're OK to nest. */
___d_drop(dentry);
___d_drop(target);
/* Switch the names.. */
if (exchange)
@ -2829,6 +2836,8 @@ static void __d_move(struct dentry *dentry, struct dentry *target,
__d_rehash(dentry);
if (exchange)
__d_rehash(target);
else
target->d_hash.pprev = NULL;
/* ... and switch them in the tree */
if (IS_ROOT(dentry)) {