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udf: fix the udf_iget() vs. udf_new_inode() races 

Currently udf_iget() (triggered by NFS) can race with udf_new_inode()
leading to two inode structures with the same inode number:

nfsd: iget_locked() creates inode
nfsd: try to read from disk, block on that.
udf_new_inode(): allocate inode with that inumber
udf_new_inode(): insert it into icache, set it up and dirty
udf_write_inode(): write inode into buffer cache
nfsd: get CPU again, look into buffer cache, see nice and sane on-disk
  inode, set the in-core inode from it

Fix the problem by putting inode into icache in locked state (I_NEW set)
and unlocking it only after it's fully set up.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Al Viro 2014-09-04 09:38:11 -04:00 committed by Jan Kara
parent d2be51cb34
commit b231509616
2 changed files with 13 additions and 1 deletions
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7
fs/udf/ialloc.c
View File

@ -124,7 +124,12 @@ struct inode *udf_new_inode(struct inode *dir, umode_t mode, int *err)
iinfo->i_alloc_type = ICBTAG_FLAG_AD_LONG;
inode->i_mtime = inode->i_atime = inode->i_ctime =
iinfo->i_crtime = current_fs_time(inode->i_sb);
insert_inode_hash(inode);
if (unlikely(insert_inode_locked(inode) < 0)) {
make_bad_inode(inode);
iput(inode);
*err = -EIO;
return NULL;
}
mark_inode_dirty(inode);
*err = 0;

7
fs/udf/namei.c
View File

@ -559,6 +559,7 @@ static int udf_add_nondir(struct dentry *dentry, struct inode *inode)
fi = udf_add_entry(dir, dentry, &fibh, &cfi, &err);
if (unlikely(!fi)) {
inode_dec_link_count(inode);
unlock_new_inode(inode);
iput(inode);
return err;
}
@ -572,6 +573,7 @@ static int udf_add_nondir(struct dentry *dentry, struct inode *inode)
if (fibh.sbh != fibh.ebh)
brelse(fibh.ebh);
brelse(fibh.sbh);
unlock_new_inode(inode);
d_instantiate(dentry, inode);
return 0;
@ -619,6 +621,7 @@ static int udf_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
mark_inode_dirty(inode);
d_tmpfile(dentry, inode);
unlock_new_inode(inode);
return 0;
}
@ -660,6 +663,7 @@ static int udf_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
fi = udf_add_entry(inode, NULL, &fibh, &cfi, &err);
if (!fi) {
inode_dec_link_count(inode);
unlock_new_inode(inode);
iput(inode);
goto out;
}
@ -678,6 +682,7 @@ static int udf_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
if (!fi) {
clear_nlink(inode);
mark_inode_dirty(inode);
unlock_new_inode(inode);
iput(inode);
goto out;
}
@ -689,6 +694,7 @@ static int udf_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
udf_write_fi(dir, &cfi, fi, &fibh, NULL, NULL);
inc_nlink(dir);
mark_inode_dirty(dir);
unlock_new_inode(inode);
d_instantiate(dentry, inode);
if (fibh.sbh != fibh.ebh)
brelse(fibh.ebh);
@ -996,6 +1002,7 @@ static int udf_symlink(struct inode *dir, struct dentry *dentry,
out_no_entry:
up_write(&iinfo->i_data_sem);
inode_dec_link_count(inode);
unlock_new_inode(inode);
iput(inode);
goto out;
}