diff options
| -rw-r--r-- | Documentation/filesystems/nfs/exporting.rst | 12 | ||||
| -rw-r--r-- | fs/nfs/export.c | 2 | ||||
| -rw-r--r-- | fs/nfsd/export.c | 6 | ||||
| -rw-r--r-- | include/linux/exportfs.h | 1 |
4 files changed, 20 insertions, 1 deletions
diff --git a/Documentation/filesystems/nfs/exporting.rst b/Documentation/filesystems/nfs/exporting.rst index cbe542ad5233..960be64446cb 100644 --- a/Documentation/filesystems/nfs/exporting.rst +++ b/Documentation/filesystems/nfs/exporting.rst @@ -190,3 +190,15 @@ following flags are defined: this on filesystems that have an expensive ->getattr inode operation, or when atomicity between pre and post operation attribute collection is impossible to guarantee. + + EXPORT_OP_NOSUBTREECHK - disallow subtree checking on this fs + Many NFS operations deal with filehandles, which the server must then + vet to ensure that they live inside of an exported tree. When the + export consists of an entire filesystem, this is trivial. nfsd can just + ensure that the filehandle live on the filesystem. When only part of a + filesystem is exported however, then nfsd must walk the ancestors of the + inode to ensure that it's within an exported subtree. This is an + expensive operation and not all filesystems can support it properly. + This flag exempts the filesystem from subtree checking and causes + exportfs to get back an error if it tries to enable subtree checking + on it. diff --git a/fs/nfs/export.c b/fs/nfs/export.c index 8f4c528865c5..b9ba306bf912 100644 --- a/fs/nfs/export.c +++ b/fs/nfs/export.c @@ -171,5 +171,5 @@ const struct export_operations nfs_export_ops = { .encode_fh = nfs_encode_fh, .fh_to_dentry = nfs_fh_to_dentry, .get_parent = nfs_get_parent, - .flags = EXPORT_OP_NOWCC, + .flags = EXPORT_OP_NOWCC|EXPORT_OP_NOSUBTREECHK, }; diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c index 21e404e7cb68..81e7bb12aca6 100644 --- a/fs/nfsd/export.c +++ b/fs/nfsd/export.c @@ -408,6 +408,12 @@ static int check_export(struct inode *inode, int *flags, unsigned char *uuid) return -EINVAL; } + if (inode->i_sb->s_export_op->flags & EXPORT_OP_NOSUBTREECHK && + !(*flags & NFSEXP_NOSUBTREECHECK)) { + dprintk("%s: %s does not support subtree checking!\n", + __func__, inode->i_sb->s_type->name); + return -EINVAL; + } return 0; } diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h index e7de0103a32e..2fcbab0f6b61 100644 --- a/include/linux/exportfs.h +++ b/include/linux/exportfs.h @@ -214,6 +214,7 @@ struct export_operations { int (*commit_blocks)(struct inode *inode, struct iomap *iomaps, int nr_iomaps, struct iattr *iattr); #define EXPORT_OP_NOWCC (0x1) /* Don't collect wcc data for NFSv3 replies */ +#define EXPORT_OP_NOSUBTREECHK (0x2) /* Subtree checking is not supported! */ unsigned long flags; }; |