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fuse: nfs export special lookups

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Implement the get_parent export operation by sending a LOOKUP request with
".." as the name.

Implement looking up an inode by node ID after it has been evicted from
the cache.  This is done by seding a LOOKUP request with "." as the name
(for all file types, not just directories).

The filesystem can set the FUSE_EXPORT_SUPPORT flag in the INIT reply, to
indicate that it supports these special lookups.

Thanks to John Muir for the original implementation of this feature.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: David Teigland <teigland@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Miklos Szeredi 2008-07-25 01:49:02 -07:00 committed by Linus Torvalds
parent c180eebe13
commit 33670fa296
3 changed files with 72 additions and 3 deletions
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6
fs/fuse/fuse_i.h
View File

@ -363,6 +363,9 @@ struct fuse_conn {
/** Do not send separate SETATTR request before open(O_TRUNC) */
unsigned atomic_o_trunc : 1;
/** Filesystem supports NFS exporting. Only set in INIT */
unsigned export_support : 1;
/*
* The following bitfields are only for optimization purposes
* and hence races in setting them will not cause malfunction
@ -473,6 +476,9 @@ struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
int generation, struct fuse_attr *attr,
u64 attr_valid, u64 attr_version);
int fuse_lookup_name(struct super_block *sb, u64 nodeid, struct qstr *name,
struct fuse_entry_out *outarg, struct inode **inode);
/**
* Send FORGET command
*/

66
fs/fuse/inode.c
View File

@ -562,6 +562,7 @@ struct fuse_inode_handle
static struct dentry *fuse_get_dentry(struct super_block *sb,
struct fuse_inode_handle *handle)
{
struct fuse_conn *fc = get_fuse_conn_super(sb);
struct inode *inode;
struct dentry *entry;
int err = -ESTALE;
@ -570,8 +571,27 @@ static struct dentry *fuse_get_dentry(struct super_block *sb,
goto out_err;
inode = ilookup5(sb, handle->nodeid, fuse_inode_eq, &handle->nodeid);
if (!inode)
goto out_err;
if (!inode) {
struct fuse_entry_out outarg;
struct qstr name;
if (!fc->export_support)
goto out_err;
name.len = 1;
name.name = ".";
err = fuse_lookup_name(sb, handle->nodeid, &name, &outarg,
&inode);
if (err && err != -ENOENT)
goto out_err;
if (err || !inode) {
err = -ESTALE;
goto out_err;
}
err = -EIO;
if (get_node_id(inode) != handle->nodeid)
goto out_iput;
}
err = -ESTALE;
if (inode->i_generation != handle->generation)
goto out_iput;
@ -659,11 +679,46 @@ static struct dentry *fuse_fh_to_parent(struct super_block *sb,
return fuse_get_dentry(sb, &parent);
}
static struct dentry *fuse_get_parent(struct dentry *child)
{
struct inode *child_inode = child->d_inode;
struct fuse_conn *fc = get_fuse_conn(child_inode);
struct inode *inode;
struct dentry *parent;
struct fuse_entry_out outarg;
struct qstr name;
int err;
if (!fc->export_support)
return ERR_PTR(-ESTALE);
name.len = 2;
name.name = "..";
err = fuse_lookup_name(child_inode->i_sb, get_node_id(child_inode),
&name, &outarg, &inode);
if (err && err != -ENOENT)
return ERR_PTR(err);
if (err || !inode)
return ERR_PTR(-ESTALE);
parent = d_alloc_anon(inode);
if (!parent) {
iput(inode);
return ERR_PTR(-ENOMEM);
}
if (get_node_id(inode) != FUSE_ROOT_ID) {
parent->d_op = &fuse_dentry_operations;
fuse_invalidate_entry_cache(parent);
}
return parent;
}
static const struct export_operations fuse_export_operations = {
.fh_to_dentry = fuse_fh_to_dentry,
.fh_to_parent = fuse_fh_to_parent,
.encode_fh = fuse_encode_fh,
.get_parent = fuse_get_parent,
};
static const struct super_operations fuse_super_operations = {
@ -695,6 +750,11 @@ static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
fc->no_lock = 1;
if (arg->flags & FUSE_ATOMIC_O_TRUNC)
fc->atomic_o_trunc = 1;
if (arg->minor >= 9) {
/* LOOKUP has dependency on proto version */
if (arg->flags & FUSE_EXPORT_SUPPORT)
fc->export_support = 1;
}
if (arg->flags & FUSE_BIG_WRITES)
fc->big_writes = 1;
} else {
@ -721,7 +781,7 @@ static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)
arg->minor = FUSE_KERNEL_MINOR_VERSION;
arg->max_readahead = fc->bdi.ra_pages * PAGE_CACHE_SIZE;
arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC |
FUSE_BIG_WRITES;
FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES;
req->in.h.opcode = FUSE_INIT;
req->in.numargs = 1;
req->in.args[0].size = sizeof(*arg);

3
include/linux/fuse.h
View File

@ -104,11 +104,14 @@ struct fuse_file_lock {
/**
* INIT request/reply flags
*
* FUSE_EXPORT_SUPPORT: filesystem handles lookups of "." and ".."
*/
#define FUSE_ASYNC_READ (1 << 0)
#define FUSE_POSIX_LOCKS (1 << 1)
#define FUSE_FILE_OPS (1 << 2)
#define FUSE_ATOMIC_O_TRUNC (1 << 3)
#define FUSE_EXPORT_SUPPORT (1 << 4)
#define FUSE_BIG_WRITES (1 << 5)
/**