From: Miklos Szeredi <miklos@szeredi.hu>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Vivek Goyal <vgoyal@redhat.com>,
Al Viro <viro@zeniv.linux.org.uk>,
overlayfs <linux-unionfs@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH v3 1/4] ovl: use insert_inode_locked4() to hash a newly created inode
Date: Thu, 17 May 2018 10:53:05 +0200 [thread overview]
Message-ID: <20180517085305.GA23785@veci.piliscsaba.redhat.com> (raw)
In-Reply-To: <CAJfpegtC=FHdHAr5WKoMpX+aBTsMQB9Ffv0NfFouuSA3M08sqQ@mail.gmail.com>
On Thu, May 17, 2018 at 10:10:58AM +0200, Miklos Szeredi wrote:
>
> Not the only reason: we don't want inode allocation to fail after
> successful creation. Solution: add a preallocated inode argument to
> ovl_get_inode() and deal with allocation failure there.
Here's a patch to split a helper out of iget5_locked() that takes a preallocated
inode. It makes the whole thing more readable, IMO, regardless of overlayfs's
needs.
Thanks,
Miklos
---
diff --git a/fs/inode.c b/fs/inode.c
index 13ceb98c3bd3..bb79e3f96147 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1002,6 +1002,52 @@ void unlock_two_nondirectories(struct inode *inode1, struct inode *inode2)
}
EXPORT_SYMBOL(unlock_two_nondirectories);
+struct inode *iget5_prealloc(struct inode *inode,
+ struct super_block *sb, unsigned long hashval,
+ int (*test)(struct inode *, void *),
+ int (*set)(struct inode *, void *), void *data)
+{
+ struct hlist_head *head = inode_hashtable + hash(sb, hashval);
+ struct inode *old;
+
+again:
+ spin_lock(&inode_hash_lock);
+ old = find_inode(sb, head, test, data);
+ if (unlikely(old)) {
+ /*
+ * Uhhuh, somebody else created the same inode under us.
+ * Use the old inode instead of the preallocated one.
+ */
+ spin_unlock(&inode_hash_lock);
+ wait_on_inode(old);
+ if (unlikely(inode_unhashed(old))) {
+ iput(old);
+ goto again;
+ }
+ return old;
+ }
+
+ if (unlikely(set(inode, data))) {
+ inode = NULL;
+ goto unlock;
+ }
+
+ /*
+ * Return the locked inode with I_NEW set, the
+ * caller is responsible for filling in the contents
+ */
+ 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);
+unlock:
+ spin_unlock(&inode_hash_lock);
+
+ return inode;
+}
+EXPORT_SYMBOL(iget5_prealloc);
+
/**
* iget5_locked - obtain an inode from a mounted file system
* @sb: super block of file system
@@ -1026,66 +1072,18 @@ struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
int (*test)(struct inode *, void *),
int (*set)(struct inode *, void *), void *data)
{
- struct hlist_head *head = inode_hashtable + hash(sb, hashval);
- struct inode *inode;
-again:
- spin_lock(&inode_hash_lock);
- inode = find_inode(sb, head, test, data);
- spin_unlock(&inode_hash_lock);
+ struct inode *inode = ilookup5(sb, hashval, test, data);
- if (inode) {
- wait_on_inode(inode);
- if (unlikely(inode_unhashed(inode))) {
- iput(inode);
- goto again;
- }
- return inode;
- }
-
- inode = alloc_inode(sb);
- if (inode) {
- struct inode *old;
-
- spin_lock(&inode_hash_lock);
- /* We released the lock, so.. */
- old = find_inode(sb, head, test, data);
- if (!old) {
- 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);
- spin_unlock(&inode_hash_lock);
-
- /* Return the locked inode with I_NEW set, the
- * caller is responsible for filling in the contents
- */
- return inode;
- }
+ if (!inode) {
+ struct inode *new = alloc_inode(sb);
- /*
- * Uhhuh, somebody else created the same inode under
- * us. Use the old inode instead of the one we just
- * allocated.
- */
- spin_unlock(&inode_hash_lock);
- destroy_inode(inode);
- inode = old;
- wait_on_inode(inode);
- if (unlikely(inode_unhashed(inode))) {
- iput(inode);
- goto again;
+ if (new) {
+ inode = iget5_prealloc(new, sb, hashval, test, set, data);
+ if (inode != new)
+ destroy_inode(new);
}
}
return inode;
-
-set_failed:
- spin_unlock(&inode_hash_lock);
- destroy_inode(inode);
- return NULL;
}
EXPORT_SYMBOL(iget5_locked);
next prev parent reply other threads:[~2018-05-17 8:53 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-15 10:26 [PATCH v3 0/4] Overlayfs mkdir related fixes Amir Goldstein
2018-05-15 10:26 ` [PATCH v3 1/4] ovl: use insert_inode_locked4() to hash a newly created inode Amir Goldstein
2018-05-15 13:23 ` Vivek Goyal
2018-05-15 13:37 ` Amir Goldstein
2018-05-16 8:34 ` Miklos Szeredi
2018-05-16 9:51 ` Amir Goldstein
2018-05-16 10:14 ` Miklos Szeredi
2018-05-16 11:03 ` Amir Goldstein
2018-05-17 6:03 ` Amir Goldstein
2018-05-17 8:10 ` Miklos Szeredi
2018-05-17 8:45 ` Amir Goldstein
2018-05-17 8:53 ` Miklos Szeredi [this message]
2018-05-17 8:58 ` Amir Goldstein
2018-05-17 9:07 ` Miklos Szeredi
2018-05-17 16:14 ` Amir Goldstein
2018-05-15 10:26 ` [PATCH v3 2/4] ovl: relax WARN_ON() real inode attributes mismatch Amir Goldstein
2018-05-15 12:48 ` Vivek Goyal
2018-05-15 12:55 ` Amir Goldstein
2018-05-16 10:29 ` Miklos Szeredi
2018-05-16 11:06 ` Amir Goldstein
2018-05-16 11:18 ` Miklos Szeredi
2018-05-16 13:46 ` Amir Goldstein
2018-05-15 10:26 ` [PATCH v3 3/4] ovl: create helper ovl_create_temp() Amir Goldstein
2018-05-16 10:41 ` Miklos Szeredi
2018-05-16 11:15 ` Amir Goldstein
2018-05-16 11:37 ` Miklos Szeredi
2018-05-15 10:26 ` [PATCH v3 4/4] ovl: make ovl_create_real() cope with vfs_mkdir() safely Amir Goldstein
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