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NFSD: use explicit lock/unlock for directory ops 

When creating or unlinking a name in a directory use explicit
inode_lock_nested() instead of fh_lock(), and explicit calls to
fh_fill_pre_attrs() and fh_fill_post_attrs().  This is already done
for renames, with lock_rename() as the explicit locking.

Also move the 'fill' calls closer to the operation that might change the
attributes.  This way they are avoided on some error paths.

For the v2-only code in nfsproc.c, the fill calls are not replaced as
they aren't needed.

Making the locking explicit will simplify proposed future changes to
locking for directories.  It also makes it easily visible exactly where
pre/post attributes are used - not all callers of fh_lock() actually
need the pre/post attributes.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
NeilBrown 2022-07-26 16:45:30 +10:00 committed by Chuck Lever
parent 19d008b469
commit debf16f0c6
4 changed files with 29 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
fs/nfsd/nfs3proc.c
View File

@ -260,7 +260,7 @@ nfsd3_create_file(struct svc_rqst *rqstp, struct svc_fh *fhp,
if (host_err)
return nfserrno(host_err);
fh_lock_nested(fhp, I_MUTEX_PARENT);
inode_lock_nested(inode, I_MUTEX_PARENT);
child = lookup_one_len(argp->name, parent, argp->len);
if (IS_ERR(child)) {
@ -318,11 +318,13 @@ nfsd3_create_file(struct svc_rqst *rqstp, struct svc_fh *fhp,
if (!IS_POSIXACL(inode))
iap->ia_mode &= ~current_umask();
fh_fill_pre_attrs(fhp);
host_err = vfs_create(&init_user_ns, inode, child, iap->ia_mode, true);
if (host_err < 0) {
status = nfserrno(host_err);
goto out;
}
fh_fill_post_attrs(fhp);
/* A newly created file already has a file size of zero. */
if ((iap->ia_valid & ATTR_SIZE) && (iap->ia_size == 0))
@ -340,7 +342,7 @@ set_attr:
status = nfsd_create_setattr(rqstp, fhp, resfhp, &attrs);
out:
fh_unlock(fhp);
inode_unlock(inode);
if (child && !IS_ERR(child))
dput(child);
fh_drop_write(fhp);

6
fs/nfsd/nfs4proc.c
View File

@ -264,7 +264,7 @@ nfsd4_create_file(struct svc_rqst *rqstp, struct svc_fh *fhp,
if (is_create_with_attrs(open))
nfsd4_acl_to_attr(NF4REG, open->op_acl, &attrs);
fh_lock_nested(fhp, I_MUTEX_PARENT);
inode_lock_nested(inode, I_MUTEX_PARENT);
child = lookup_one_len(open->op_fname, parent, open->op_fnamelen);
if (IS_ERR(child)) {
@ -348,10 +348,12 @@ nfsd4_create_file(struct svc_rqst *rqstp, struct svc_fh *fhp,
if (!IS_POSIXACL(inode))
iap->ia_mode &= ~current_umask();
fh_fill_pre_attrs(fhp);
status = nfsd4_vfs_create(fhp, child, open);
if (status != nfs_ok)
goto out;
open->op_created = true;
fh_fill_post_attrs(fhp);
/* A newly created file already has a file size of zero. */
if ((iap->ia_valid & ATTR_SIZE) && (iap->ia_size == 0))
@ -373,7 +375,7 @@ set_attr:
if (attrs.na_aclerr)
open->op_bmval[0] &= ~FATTR4_WORD0_ACL;
out:
fh_unlock(fhp);
inode_unlock(inode);
nfsd_attrs_free(&attrs);
if (child && !IS_ERR(child))
dput(child);

5
fs/nfsd/nfsproc.c
View File

@ -291,7 +291,7 @@ nfsd_proc_create(struct svc_rqst *rqstp)
goto done;
}
fh_lock_nested(dirfhp, I_MUTEX_PARENT);
inode_lock_nested(dirfhp->fh_dentry->d_inode, I_MUTEX_PARENT);
dchild = lookup_one_len(argp->name, dirfhp->fh_dentry, argp->len);
if (IS_ERR(dchild)) {
resp->status = nfserrno(PTR_ERR(dchild));
@ -407,8 +407,7 @@ nfsd_proc_create(struct svc_rqst *rqstp)
}
out_unlock:
/* We don't really need to unlock, as fh_put does it. */
fh_unlock(dirfhp);
inode_unlock(dirfhp->fh_dentry->d_inode);
fh_drop_write(dirfhp);
done:
fh_put(dirfhp);

30
fs/nfsd/vfs.c
View File

@ -1370,7 +1370,7 @@ nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
if (host_err)
return nfserrno(host_err);
fh_lock_nested(fhp, I_MUTEX_PARENT);
inode_lock_nested(dentry->d_inode, I_MUTEX_PARENT);
dchild = lookup_one_len(fname, dentry, flen);
host_err = PTR_ERR(dchild);
if (IS_ERR(dchild)) {
@ -1385,10 +1385,12 @@ nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
dput(dchild);
if (err)
goto out_unlock;
fh_fill_pre_attrs(fhp);
err = nfsd_create_locked(rqstp, fhp, fname, flen, attrs, type,
rdev, resfhp);
fh_fill_post_attrs(fhp);
out_unlock:
fh_unlock(fhp);
inode_unlock(dentry->d_inode);
return err;
}
@ -1471,20 +1473,22 @@ nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
goto out;
}
fh_lock(fhp);
dentry = fhp->fh_dentry;
inode_lock_nested(dentry->d_inode, I_MUTEX_PARENT);
dnew = lookup_one_len(fname, dentry, flen);
if (IS_ERR(dnew)) {
err = nfserrno(PTR_ERR(dnew));
fh_unlock(fhp);
inode_unlock(dentry->d_inode);
goto out_drop_write;
}
fh_fill_pre_attrs(fhp);
host_err = vfs_symlink(&init_user_ns, d_inode(dentry), dnew, path);
err = nfserrno(host_err);
cerr = fh_compose(resfhp, fhp->fh_export, dnew, fhp);
if (!err)
nfsd_create_setattr(rqstp, fhp, resfhp, attrs);
fh_unlock(fhp);
fh_fill_post_attrs(fhp);
inode_unlock(dentry->d_inode);
if (!err)
err = nfserrno(commit_metadata(fhp));
dput(dnew);
@ -1530,9 +1534,9 @@ nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
goto out;
}
fh_lock_nested(ffhp, I_MUTEX_PARENT);
ddir = ffhp->fh_dentry;
dirp = d_inode(ddir);
inode_lock_nested(dirp, I_MUTEX_PARENT);
dnew = lookup_one_len(name, ddir, len);
if (IS_ERR(dnew)) {
@ -1545,8 +1549,10 @@ nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
err = nfserr_noent;
if (d_really_is_negative(dold))
goto out_dput;
fh_fill_pre_attrs(ffhp);
host_err = vfs_link(dold, &init_user_ns, dirp, dnew, NULL);
fh_unlock(ffhp);
fh_fill_post_attrs(ffhp);
inode_unlock(dirp);
if (!host_err) {
err = nfserrno(commit_metadata(ffhp));
if (!err)
@ -1566,7 +1572,7 @@ out:
out_dput:
dput(dnew);
out_unlock:
fh_unlock(ffhp);
inode_unlock(dirp);
goto out_drop_write;
}
@ -1741,9 +1747,9 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
if (host_err)
goto out_nfserr;
fh_lock_nested(fhp, I_MUTEX_PARENT);
dentry = fhp->fh_dentry;
dirp = d_inode(dentry);
inode_lock_nested(dirp, I_MUTEX_PARENT);
rdentry = lookup_one_len(fname, dentry, flen);
host_err = PTR_ERR(rdentry);
@ -1761,6 +1767,7 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
if (!type)
type = d_inode(rdentry)->i_mode & S_IFMT;
fh_fill_pre_attrs(fhp);
if (type != S_IFDIR) {
if (rdentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK)
nfsd_close_cached_files(rdentry);
@ -1768,8 +1775,9 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
} else {
host_err = vfs_rmdir(&init_user_ns, dirp, rdentry);
}
fh_fill_post_attrs(fhp);
fh_unlock(fhp);
inode_unlock(dirp);
if (!host_err)
host_err = commit_metadata(fhp);
dput(rdentry);
@ -1792,7 +1800,7 @@ out_nfserr:
out:
return err;
out_unlock:
fh_unlock(fhp);
inode_unlock(dirp);
goto out_drop_write;
}