nfsd: Push mnt_want_write() outside of i_mutex

When mnt_want_write() starts to handle freezing it will get a full lock
semantics requiring proper lock ordering. So push mnt_want_write() call
consistently outside of i_mutex.

CC: linux-nfs@vger.kernel.org
CC: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
index 5ff0b7b9fc08f22f39cc1f2d83062baceb773bdc..43295d45cc2b553e2afda4d11d7b2d429b8676ef 100644 (file)
--- a/fs/nfsd/nfs4recover.c
+++ b/fs/nfsd/nfs4recover.c
@@ -154,6 +154,10 @@ nfsd4_create_clid_dir(struct nfs4_client *clp)
        if (status < 0)
                return;
 
+       status = mnt_want_write_file(rec_file);
+       if (status)
+               return;
+
        dir = rec_file->f_path.dentry;
        /* lock the parent */
        mutex_lock(&dir->d_inode->i_mutex);
@@ -173,11 +177,7 @@ nfsd4_create_clid_dir(struct nfs4_client *clp)
                 * as well be forgiving and just succeed silently.
                 */
                goto out_put;
-       status = mnt_want_write_file(rec_file);
-       if (status)
-               goto out_put;
        status = vfs_mkdir(dir->d_inode, dentry, S_IRWXU);
-       mnt_drop_write_file(rec_file);
 out_put:
        dput(dentry);
 out_unlock:
@@ -189,6 +189,7 @@ out_unlock:
                                " (err %d); please check that %s exists"
                                " and is writeable", status,
                                user_recovery_dirname);
+       mnt_drop_write_file(rec_file);
        nfs4_reset_creds(original_cred);
 }
 

diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c
index cc793005a87cb4b5a79b7074c4861ca651085d1c..032af381b3aa4bd1298b084c57d3c4022293668c 100644 (file)
--- a/fs/nfsd/nfsfh.c
+++ b/fs/nfsd/nfsfh.c
@@ -635,6 +635,7 @@ fh_put(struct svc_fh *fhp)
                fhp->fh_post_saved = 0;
 #endif
        }
+       fh_drop_write(fhp);
        if (exp) {
                exp_put(exp);
                fhp->fh_export = NULL;

diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
index e15dc45fc5ec01c09a05d42b8ac600ed39e3892f..aad6d457b9e8ef75d410d01de3dd6bac692c96fd 100644 (file)
--- a/fs/nfsd/nfsproc.c
+++ b/fs/nfsd/nfsproc.c
@@ -196,6 +196,7 @@ nfsd_proc_create(struct svc_rqst *rqstp, struct nfsd_createargs *argp,
        struct dentry   *dchild;
        int             type, mode;
        __be32          nfserr;
+       int             hosterr;
        dev_t           rdev = 0, wanted = new_decode_dev(attr->ia_size);
 
        dprintk("nfsd: CREATE   %s %.*s\n",
@@ -214,6 +215,12 @@ nfsd_proc_create(struct svc_rqst *rqstp, struct nfsd_createargs *argp,
        nfserr = nfserr_exist;
        if (isdotent(argp->name, argp->len))
                goto done;
+       hosterr = fh_want_write(dirfhp);
+       if (hosterr) {
+               nfserr = nfserrno(hosterr);
+               goto done;
+       }
+
        fh_lock_nested(dirfhp, I_MUTEX_PARENT);
        dchild = lookup_one_len(argp->name, dirfhp->fh_dentry, argp->len);
        if (IS_ERR(dchild)) {
@@ -330,7 +337,7 @@ nfsd_proc_create(struct svc_rqst *rqstp, struct nfsd_createargs *argp,
 out_unlock:
        /* We don't really need to unlock, as fh_put does it. */
        fh_unlock(dirfhp);
-
+       fh_drop_write(dirfhp);
 done:
        fh_put(dirfhp);
        return nfsd_return_dirop(nfserr, resp);

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 4700a0a929d72baeb0c86024a1c5051e6d19cab5..dccd396a1bb75f8428ba4c71b4713f759ab9f381 100644 (file)
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1276,6 +1276,10 @@ nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
         * If it has, the parent directory should already be locked.
         */
        if (!resfhp->fh_dentry) {
+               host_err = fh_want_write(fhp);
+               if (host_err)
+                       goto out_nfserr;
+
                /* called from nfsd_proc_mkdir, or possibly nfsd3_proc_create */
                fh_lock_nested(fhp, I_MUTEX_PARENT);
                dchild = lookup_one_len(fname, dentry, flen);
@@ -1319,14 +1323,11 @@ nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
                goto out;
        }
 
-       host_err = fh_want_write(fhp);
-       if (host_err)
-               goto out_nfserr;
-
        /*
         * Get the dir op function pointer.
         */
        err = 0;
+       host_err = 0;
        switch (type) {
        case S_IFREG:
                host_err = vfs_create(dirp, dchild, iap->ia_mode, true);
@@ -1343,10 +1344,8 @@ nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
                host_err = vfs_mknod(dirp, dchild, iap->ia_mode, rdev);
                break;
        }
-       if (host_err < 0) {
-               fh_drop_write(fhp);
+       if (host_err < 0)
                goto out_nfserr;
-       }
 
        err = nfsd_create_setattr(rqstp, resfhp, iap);
 
@@ -1358,7 +1357,6 @@ nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
        err2 = nfserrno(commit_metadata(fhp));
        if (err2)
                err = err2;
-       fh_drop_write(fhp);
        /*
         * Update the file handle to get the new inode info.
         */
@@ -1417,6 +1415,11 @@ do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
        err = nfserr_notdir;
        if (!dirp->i_op->lookup)
                goto out;
+
+       host_err = fh_want_write(fhp);
+       if (host_err)
+               goto out_nfserr;
+
        fh_lock_nested(fhp, I_MUTEX_PARENT);
 
        /*
@@ -1449,9 +1452,6 @@ do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
                v_atime = verifier[1]&0x7fffffff;
        }
        
-       host_err = fh_want_write(fhp);
-       if (host_err)
-               goto out_nfserr;
        if (dchild->d_inode) {
                err = 0;
 
@@ -1522,7 +1522,6 @@ do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
        if (!err)
                err = nfserrno(commit_metadata(fhp));
 
-       fh_drop_write(fhp);
        /*
         * Update the filehandle to get the new inode info.
         */
@@ -1533,6 +1532,7 @@ do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
        fh_unlock(fhp);
        if (dchild && !IS_ERR(dchild))
                dput(dchild);
+       fh_drop_write(fhp);
        return err;
  
  out_nfserr:
@@ -1613,6 +1613,11 @@ nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
        err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
        if (err)
                goto out;
+
+       host_err = fh_want_write(fhp);
+       if (host_err)
+               goto out_nfserr;
+
        fh_lock(fhp);
        dentry = fhp->fh_dentry;
        dnew = lookup_one_len(fname, dentry, flen);
@@ -1620,10 +1625,6 @@ nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
        if (IS_ERR(dnew))
                goto out_nfserr;
 
-       host_err = fh_want_write(fhp);
-       if (host_err)
-               goto out_nfserr;
-
        if (unlikely(path[plen] != 0)) {
                char *path_alloced = kmalloc(plen+1, GFP_KERNEL);
                if (path_alloced == NULL)
@@ -1683,6 +1684,12 @@ nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
        if (isdotent(name, len))
                goto out;
 
+       host_err = fh_want_write(tfhp);
+       if (host_err) {
+               err = nfserrno(host_err);
+               goto out;
+       }
+
        fh_lock_nested(ffhp, I_MUTEX_PARENT);
        ddir = ffhp->fh_dentry;
        dirp = ddir->d_inode;
@@ -1694,18 +1701,13 @@ nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
 
        dold = tfhp->fh_dentry;
 
-       host_err = fh_want_write(tfhp);
-       if (host_err) {
-               err = nfserrno(host_err);
-               goto out_dput;
-       }
        err = nfserr_noent;
        if (!dold->d_inode)
-               goto out_drop_write;
+               goto out_dput;
        host_err = nfsd_break_lease(dold->d_inode);
        if (host_err) {
                err = nfserrno(host_err);
-               goto out_drop_write;
+               goto out_dput;
        }
        host_err = vfs_link(dold, dirp, dnew);
        if (!host_err) {
@@ -1718,12 +1720,11 @@ nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
                else
                        err = nfserrno(host_err);
        }
-out_drop_write:
-       fh_drop_write(tfhp);
 out_dput:
        dput(dnew);
 out_unlock:
        fh_unlock(ffhp);
+       fh_drop_write(tfhp);
 out:
        return err;
 
@@ -1766,6 +1767,12 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
        if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen))
                goto out;
 
+       host_err = fh_want_write(ffhp);
+       if (host_err) {
+               err = nfserrno(host_err);
+               goto out;
+       }
+
        /* cannot use fh_lock as we need deadlock protective ordering
         * so do it by hand */
        trap = lock_rename(tdentry, fdentry);
@@ -1796,17 +1803,14 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
        host_err = -EXDEV;
        if (ffhp->fh_export->ex_path.mnt != tfhp->fh_export->ex_path.mnt)
                goto out_dput_new;
-       host_err = fh_want_write(ffhp);
-       if (host_err)
-               goto out_dput_new;
 
        host_err = nfsd_break_lease(odentry->d_inode);
        if (host_err)
-               goto out_drop_write;
+               goto out_dput_new;
        if (ndentry->d_inode) {
                host_err = nfsd_break_lease(ndentry->d_inode);
                if (host_err)
-                       goto out_drop_write;
+                       goto out_dput_new;
        }
        host_err = vfs_rename(fdir, odentry, tdir, ndentry);
        if (!host_err) {
@@ -1814,8 +1818,6 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
                if (!host_err)
                        host_err = commit_metadata(ffhp);
        }
-out_drop_write:
-       fh_drop_write(ffhp);
  out_dput_new:
        dput(ndentry);
  out_dput_old:
@@ -1831,6 +1833,7 @@ out_drop_write:
        fill_post_wcc(tfhp);
        unlock_rename(tdentry, fdentry);
        ffhp->fh_locked = tfhp->fh_locked = 0;
+       fh_drop_write(ffhp);
 
 out:
        return err;
@@ -1856,6 +1859,10 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
        if (err)
                goto out;
 
+       host_err = fh_want_write(fhp);
+       if (host_err)
+               goto out_nfserr;
+
        fh_lock_nested(fhp, I_MUTEX_PARENT);
        dentry = fhp->fh_dentry;
        dirp = dentry->d_inode;
@@ -1874,21 +1881,15 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
        if (!type)
                type = rdentry->d_inode->i_mode & S_IFMT;
 
-       host_err = fh_want_write(fhp);
-       if (host_err)
-               goto out_put;
-
        host_err = nfsd_break_lease(rdentry->d_inode);
        if (host_err)
-               goto out_drop_write;
+               goto out_put;
        if (type != S_IFDIR)
                host_err = vfs_unlink(dirp, rdentry);
        else
                host_err = vfs_rmdir(dirp, rdentry);
        if (!host_err)
                host_err = commit_metadata(fhp);
-out_drop_write:
-       fh_drop_write(fhp);
 out_put:
        dput(rdentry);
 

diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h
index ec0611b2b738468fbc261b35f2190048680e67dd..359594c393d273f20b5fe3ef0a9a75379ab1edc2 100644 (file)
--- a/fs/nfsd/vfs.h
+++ b/fs/nfsd/vfs.h
@@ -110,12 +110,19 @@ int nfsd_set_posix_acl(struct svc_fh *, int, struct posix_acl *);
 
 static inline int fh_want_write(struct svc_fh *fh)
 {
-       return mnt_want_write(fh->fh_export->ex_path.mnt);
+       int ret = mnt_want_write(fh->fh_export->ex_path.mnt);
+
+       if (!ret)
+               fh->fh_want_write = 1;
+       return ret;
 }
 
 static inline void fh_drop_write(struct svc_fh *fh)
 {
-       mnt_drop_write(fh->fh_export->ex_path.mnt);
+       if (fh->fh_want_write) {
+               fh->fh_want_write = 0;
+               mnt_drop_write(fh->fh_export->ex_path.mnt);
+       }
 }
 
 #endif /* LINUX_NFSD_VFS_H */

diff --git a/include/linux/nfsd/nfsfh.h b/include/linux/nfsd/nfsfh.h
index ce4743a260152724e8609fb96883177ad92c4875..fa63048fecff82e8e5849c1487d583c49194313c 100644 (file)
--- a/include/linux/nfsd/nfsfh.h
+++ b/include/linux/nfsd/nfsfh.h
@@ -143,6 +143,7 @@ typedef struct svc_fh {
        int                     fh_maxsize;     /* max size for fh_handle */
 
        unsigned char           fh_locked;      /* inode locked by us */
+       unsigned char           fh_want_write;  /* remount protection taken */
 
 #ifdef CONFIG_NFSD_V3
        unsigned char           fh_post_saved;  /* post-op attrs saved */