nfsd race fixes: ext2
* make ext2_new_inode() put the inode into icache in locked state
* do not unlock until the inode is fully set up; otherwise nfsd
might pick it in half-baked state.
* make sure that ext2_new_inode() does *not* lead to two inodes with the
same inumber hashed at the same time; otherwise a bogus fhandle coming
from nfsd might race with inode creation:
nfsd: iget_locked() creates inode
nfsd: try to read from disk, block on that.
ext2_new_inode(): allocate inode with that inumber
ext2_new_inode(): insert it into icache, set it up and dirty
ext2_write_inode(): get the relevant part of inode table in cache,
set the entry for our inode (and start writing to disk)
nfsd: get CPU again, look into inode table, see nice and sane on-disk
inode, set the in-core inode from it
oops - we have two in-core inodes with the same inumber live in icache,
both used for IO. Welcome to fs corruption...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/ext2/ialloc.c b/fs/ext2/ialloc.c
index 8d0add6..c454d5d 100644
--- a/fs/ext2/ialloc.c
+++ b/fs/ext2/ialloc.c
@@ -585,7 +585,10 @@
spin_lock(&sbi->s_next_gen_lock);
inode->i_generation = sbi->s_next_generation++;
spin_unlock(&sbi->s_next_gen_lock);
- insert_inode_hash(inode);
+ if (insert_inode_locked(inode) < 0) {
+ err = -EINVAL;
+ goto fail_drop;
+ }
if (DQUOT_ALLOC_INODE(inode)) {
err = -EDQUOT;
@@ -612,6 +615,7 @@
DQUOT_DROP(inode);
inode->i_flags |= S_NOQUOTA;
inode->i_nlink = 0;
+ unlock_new_inode(inode);
iput(inode);
return ERR_PTR(err);
diff --git a/fs/ext2/namei.c b/fs/ext2/namei.c
index 2a74725..90ea179 100644
--- a/fs/ext2/namei.c
+++ b/fs/ext2/namei.c
@@ -41,9 +41,11 @@
int err = ext2_add_link(dentry, inode);
if (!err) {
d_instantiate(dentry, inode);
+ unlock_new_inode(inode);
return 0;
}
inode_dec_link_count(inode);
+ unlock_new_inode(inode);
iput(inode);
return err;
}
@@ -170,6 +172,7 @@
out_fail:
inode_dec_link_count(inode);
+ unlock_new_inode(inode);
iput (inode);
goto out;
}
@@ -178,6 +181,7 @@
struct dentry *dentry)
{
struct inode *inode = old_dentry->d_inode;
+ int err;
if (inode->i_nlink >= EXT2_LINK_MAX)
return -EMLINK;
@@ -186,7 +190,14 @@
inode_inc_link_count(inode);
atomic_inc(&inode->i_count);
- return ext2_add_nondir(dentry, inode);
+ err = ext2_add_link(dentry, inode);
+ if (!err) {
+ d_instantiate(dentry, inode);
+ return 0;
+ }
+ inode_dec_link_count(inode);
+ iput(inode);
+ return err;
}
static int ext2_mkdir(struct inode * dir, struct dentry * dentry, int mode)
@@ -222,12 +233,14 @@
goto out_fail;
d_instantiate(dentry, inode);
+ unlock_new_inode(inode);
out:
return err;
out_fail:
inode_dec_link_count(inode);
inode_dec_link_count(inode);
+ unlock_new_inode(inode);
iput(inode);
out_dir:
inode_dec_link_count(dir);