[PATCH 3.16 293/366] do d_instantiate/unlock_new_inode combinations safely

Ben Hutchings
2018-10-14T23:11:58Z

From: Al Viro <viro@zeniv.linux.org.uk>

commit 1e2e547a93a00ebc21582c06ca3c6cfea2a309ee upstream.

For anything NFS-exported we do _not_ want to unlock new inode
before it has grown an alias; original set of fixes got the
ordering right, but missed the nasty complication in case of
lockdep being enabled - unlock_new_inode() does
lockdep_annotate_inode_mutex_key(inode)
which can only be done before anyone gets a chance to touch
->i_mutex. Unfortunately, flipping the order and doing
unlock_new_inode() before d_instantiate() opens a window when
mkdir can race with open-by-fhandle on a guessed fhandle, leading
to multiple aliases for a directory inode and all the breakage
that follows from that.

Correct solution: a new primitive (d_instantiate_new())
combining these two in the right order - lockdep annotate, then
d_instantiate(), then the rest of unlock_new_inode(). All
combinations of d_instantiate() with unlock_new_inode() should
be converted to that.

Tested-by: Mike Marshall <hubcap@omnibond.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[bwh: Backported to 3.16:
- Drop changes in orangefs
- Apply similar change to ext3
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -6019,8 +6019,7 @@ static int btrfs_mknod(struct inode *dir
goto out_unlock_inode;
} else {
btrfs_update_inode(trans, root, inode);
- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);
}

out_unlock:
@@ -6096,8 +6095,7 @@ static int btrfs_create(struct inode *di
goto out_unlock_inode;

BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);

out_unlock:
btrfs_end_transaction(trans, root);
@@ -6238,12 +6236,7 @@ static int btrfs_mkdir(struct inode *dir
if (err)
goto out_fail_inode;

- d_instantiate(dentry, inode);
- /*
- * mkdir is special. We're unlocking after we call d_instantiate
- * to avoid a race with nfsd calling d_instantiate.
- */
- unlock_new_inode(inode);
+ d_instantiate_new(dentry, inode);
drop_on_err = 0;

out_fail:
@@ -8926,8 +8919,7 @@ static int btrfs_symlink(struct inode *d
goto out_unlock_inode;
}

- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);

out_unlock:
btrfs_end_transaction(trans, root);
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1680,6 +1680,28 @@ void d_instantiate(struct dentry *entry,
}
EXPORT_SYMBOL(d_instantiate);

+/*
+ * This should be equivalent to d_instantiate() + unlock_new_inode(),
+ * with lockdep-related part of unlock_new_inode() done before
+ * anything else. Use that instead of open-coding d_instantiate()/
+ * unlock_new_inode() combinations.
+ */
+void d_instantiate_new(struct dentry *entry, struct inode *inode)
+{
+ BUG_ON(!hlist_unhashed(&entry->d_u.d_alias));
+ BUG_ON(!inode);
+ lockdep_annotate_inode_mutex_key(inode);
+ security_d_instantiate(entry, inode);
+ spin_lock(&inode->i_lock);
+ __d_instantiate(entry, inode);
+ WARN_ON(!(inode->i_state & I_NEW));
+ inode->i_state &= ~I_NEW;
+ smp_mb();
+ wake_up_bit(&inode->i_state, __I_NEW);
+ spin_unlock(&inode->i_lock);
+}
+EXPORT_SYMBOL(d_instantiate_new);
+
/**
* d_instantiate_unique - instantiate a non-aliased dentry
* @entry: dentry to instantiate
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -298,8 +298,7 @@ ecryptfs_create(struct inode *directory_
iput(ecryptfs_inode);
goto out;
}
- unlock_new_inode(ecryptfs_inode);
- d_instantiate(ecryptfs_dentry, ecryptfs_inode);
+ d_instantiate_new(ecryptfs_dentry, ecryptfs_inode);
out:
return rc;
}
--- a/fs/ext2/namei.c
+++ b/fs/ext2/namei.c
@@ -41,8 +41,7 @@ static inline int ext2_add_nondir(struct
{
int err = ext2_add_link(dentry, inode);
if (!err) {
- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);
return 0;
}
inode_dec_link_count(inode);
@@ -265,8 +264,7 @@ static int ext2_mkdir(struct inode * dir
if (err)
goto out_fail;

- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);
out:
return err;

--- a/fs/ext3/namei.c
+++ b/fs/ext3/namei.c
@@ -1671,8 +1671,7 @@ static int ext3_add_nondir(handle_t *han
int err = ext3_add_entry(handle, dentry, inode);
if (!err) {
ext3_mark_inode_dirty(handle, inode);
- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);
return 0;
}
drop_nlink(inode);
@@ -1873,8 +1872,7 @@ out_clear_inode:
if (err)
goto out_clear_inode;

- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);
out_stop:
brelse(dir_block);
ext3_journal_stop(handle);
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2227,8 +2227,7 @@ static int ext4_add_nondir(handle_t *han
int err = ext4_add_entry(handle, dentry, inode);
if (!err) {
ext4_mark_inode_dirty(handle, inode);
- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);
return 0;
}
drop_nlink(inode);
@@ -2466,8 +2465,7 @@ out_clear_inode:
err = ext4_mark_inode_dirty(handle, dir);
if (err)
goto out_clear_inode;
- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);
if (IS_DIRSYNC(dir))
ext4_handle_sync(handle);

--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -127,8 +127,7 @@ static int f2fs_create(struct inode *dir

alloc_nid_done(sbi, ino);

- d_instantiate(dentry, inode);
- unlock_new_inode(inode);
+ d_instantiate_new(dentry, inode);
return 0;
out:
handle_failed_inode(inode);
@@ -260,8 +259,7 @@ static int f2fs_symlink(struct inode *di
err = page_symlink(inode, symname, symlen);
alloc_nid_done(sbi, inode->i_ino);

- d_instantiate(dentry, inode);
- unlock_new_inode(inode);
+ d_instantiate_new(dentry, inode);
return err;
out:
handle_failed_inode(inode);
@@ -294,8 +292,7 @@ static int f2fs_mkdir(struct inode *dir,

alloc_nid_done(sbi, inode->i_ino);

- d_instantiate(dentry, inode);
- unlock_new_inode(inode);
+ d_instantiate_new(dentry, inode);

return 0;

@@ -340,8 +337,7 @@ static int f2fs_mknod(struct inode *dir,
f2fs_unlock_op(sbi);

alloc_nid_done(sbi, inode->i_ino);
- d_instantiate(dentry, inode);
- unlock_new_inode(inode);
+ d_instantiate_new(dentry, inode);
return 0;
out:
handle_failed_inode(inode);
--- a/fs/jffs2/dir.c
+++ b/fs/jffs2/dir.c
@@ -207,8 +207,7 @@ static int jffs2_create(struct inode *di
__func__, inode->i_ino, inode->i_mode, inode->i_nlink,
f->inocache->pino_nlink, inode->i_mapping->nrpages);

- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);
return 0;

fail:
@@ -427,8 +426,7 @@ static int jffs2_symlink (struct inode *
mutex_unlock(&dir_f->sem);
jffs2_complete_reservation(c);

- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);
return 0;

fail:
@@ -572,8 +570,7 @@ static int jffs2_mkdir (struct inode *di
mutex_unlock(&dir_f->sem);
jffs2_complete_reservation(c);

- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);
return 0;

fail:
@@ -747,8 +744,7 @@ static int jffs2_mknod (struct inode *di
mutex_unlock(&dir_f->sem);
jffs2_complete_reservation(c);

- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);
return 0;

fail:
--- a/fs/jfs/namei.c
+++ b/fs/jfs/namei.c
@@ -176,8 +176,7 @@ static int jfs_create(struct inode *dip,
unlock_new_inode(ip);
iput(ip);
} else {
- unlock_new_inode(ip);
- d_instantiate(dentry, ip);
+ d_instantiate_new(dentry, ip);
}

out2:
@@ -309,8 +308,7 @@ static int jfs_mkdir(struct inode *dip,
unlock_new_inode(ip);
iput(ip);
} else {
- unlock_new_inode(ip);
- d_instantiate(dentry, ip);
+ d_instantiate_new(dentry, ip);
}

out2:
@@ -1043,8 +1041,7 @@ static int jfs_symlink(struct inode *dip
unlock_new_inode(ip);
iput(ip);
} else {
- unlock_new_inode(ip);
- d_instantiate(dentry, ip);
+ d_instantiate_new(dentry, ip);
}

out2:
@@ -1424,8 +1421,7 @@ static int jfs_mknod(struct inode *dir,
unlock_new_inode(ip);
iput(ip);
} else {
- unlock_new_inode(ip);
- d_instantiate(dentry, ip);
+ d_instantiate_new(dentry, ip);
}

out1:
--- a/fs/nilfs2/namei.c
+++ b/fs/nilfs2/namei.c
@@ -50,8 +50,7 @@ static inline int nilfs_add_nondir(struc
{
int err = nilfs_add_link(dentry, inode);
if (!err) {
- d_instantiate(dentry, inode);
- unlock_new_inode(inode);
+ d_instantiate_new(dentry, inode);
return 0;
}
inode_dec_link_count(inode);
@@ -249,8 +248,7 @@ static int nilfs_mkdir(struct inode *dir
goto out_fail;

nilfs_mark_inode_dirty(inode);
- d_instantiate(dentry, inode);
- unlock_new_inode(inode);
+ d_instantiate_new(dentry, inode);
out:
if (!err)
err = nilfs_transaction_commit(dir->i_sb);
--- a/fs/reiserfs/namei.c
+++ b/fs/reiserfs/namei.c
@@ -682,8 +682,7 @@ static int reiserfs_create(struct inode
reiserfs_update_inode_transaction(inode);
reiserfs_update_inode_transaction(dir);

- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);
retval = journal_end(&th);

out_failed:
@@ -763,8 +762,7 @@ static int reiserfs_mknod(struct inode *
goto out_failed;
}

- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);
retval = journal_end(&th);

out_failed:
@@ -857,8 +855,7 @@ static int reiserfs_mkdir(struct inode *
/* the above add_entry did not update dir's stat data */
reiserfs_update_sd(&th, dir);

- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);
retval = journal_end(&th);
out_failed:
reiserfs_write_unlock(dir->i_sb);
@@ -1162,8 +1159,7 @@ static int reiserfs_symlink(struct inode
goto out_failed;
}

- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);
retval = journal_end(&th);
out_failed:
reiserfs_write_unlock(parent_dir->i_sb);
--- a/fs/udf/namei.c
+++ b/fs/udf/namei.c
@@ -576,8 +576,7 @@ static int udf_add_nondir(struct dentry
if (fibh.sbh != fibh.ebh)
brelse(fibh.ebh);
brelse(fibh.sbh);
- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);

return 0;
}
@@ -697,8 +696,7 @@ static int udf_mkdir(struct inode *dir,
udf_write_fi(dir, &cfi, fi, &fibh, NULL, NULL);
inc_nlink(dir);
mark_inode_dirty(dir);
- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);
if (fibh.sbh != fibh.ebh)
brelse(fibh.ebh);
brelse(fibh.sbh);
--- a/fs/ufs/namei.c
+++ b/fs/ufs/namei.c
@@ -38,8 +38,7 @@ static inline int ufs_add_nondir(struct
{
int err = ufs_add_link(dentry, inode);
if (!err) {
- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);
return 0;
}
inode_dec_link_count(inode);
@@ -212,8 +211,7 @@ static int ufs_mkdir(struct inode * dir,
goto out_fail;
unlock_ufs(dir->i_sb);

- unlock_new_inode(inode);
- d_instantiate(dentry, inode);
+ d_instantiate_new(dentry, inode);
out:
return err;

--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -234,6 +234,7 @@ static inline int dname_external(const s
* These are the low-level FS interfaces to the dcache..
*/
extern void d_instantiate(struct dentry *, struct inode *);
+extern void d_instantiate_new(struct dentry *, struct inode *);
extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
extern struct dentry * d_materialise_unique(struct dentry *, struct inode *);
extern int d_instantiate_no_diralias(struct dentry *, struct inode *);