[Qemu-devel] [PATCH 2/5] 9p: add 9P2000.L unlinkat operation

[Aneesh Kumar K.V]

unlinkat - Remove a directory entry

size[4] Tunlinkat tag[2] dirfid[4] name[s] flag[4]
size[4] Runlinkat tag[2]

older Tremove have the below request format

size[4] Tremove tag[2] fid[4]

The remove message is used to remove a directory entry either file or directory
The remove opreation is actually a directory opertation and should ideally have
dirfid, if not we cannot represent the fid on server with anything other than
name. We will have to derive the directory name from fid in the Tremove request.

NOTE: The operation doesn't clunk the unlink fid.

Signed-off-by: Aneesh Kumar K.V <address@hidden>
---
 fsdev/file-op-9p.h        |    1 +
 hw/9pfs/cofs.c            |   16 ++++++++++++++++
 hw/9pfs/virtio-9p-coth.h  |    1 +
 hw/9pfs/virtio-9p-local.c |   16 ++++++++++++++++
 hw/9pfs/virtio-9p.c       |   44 ++++++++++++++++++++++++++++++++++++++++++++
 hw/9pfs/virtio-9p.h       |    2 ++
 6 files changed, 80 insertions(+), 0 deletions(-)

diff --git a/fsdev/file-op-9p.h b/fsdev/file-op-9p.h
index c73ee4e..3bab550 100644
--- a/fsdev/file-op-9p.h
+++ b/fsdev/file-op-9p.h
@@ -104,6 +104,7 @@ typedef struct FileOperations
     int (*name_to_path)(FsContext *, V9fsPath *, const char *, V9fsPath *);
     int (*renameat)(FsContext *ctx, V9fsPath *olddir, const char *old_name,
                     V9fsPath *newdir, const char *new_name);
+    int (*unlinkat)(FsContext *ctx, V9fsPath *dir, const char *name, int 
flags);
     void *opaque;
 } FileOperations;
 
diff --git a/hw/9pfs/cofs.c b/hw/9pfs/cofs.c
index 44f3ac5..233597b 100644
--- a/hw/9pfs/cofs.c
+++ b/hw/9pfs/cofs.c
@@ -184,6 +184,22 @@ int v9fs_co_remove(V9fsState *s, V9fsPath *path)
     return err;
 }
 
+int v9fs_co_unlinkat(V9fsState *s, V9fsPath *path, V9fsString *name, int flags)
+{
+    int err;
+
+    qemu_co_rwlock_rdlock(&s->rename_lock);
+    v9fs_co_run_in_worker(
+        {
+            err = s->ops->unlinkat(&s->ctx, path, name->data, flags);
+            if (err < 0) {
+                err = -errno;
+            }
+        });
+    qemu_co_rwlock_unlock(&s->rename_lock);
+    return err;
+}
+
 /* Only work with path name based fid */
 int v9fs_co_rename(V9fsState *s, V9fsPath *oldpath, V9fsPath *newpath)
 {
diff --git a/hw/9pfs/virtio-9p-coth.h b/hw/9pfs/virtio-9p-coth.h
index d38553a..cd94571 100644
--- a/hw/9pfs/virtio-9p-coth.h
+++ b/hw/9pfs/virtio-9p-coth.h
@@ -77,6 +77,7 @@ extern int v9fs_co_mkdir(V9fsState *, V9fsFidState *, 
V9fsString *,
                          mode_t, uid_t, gid_t, struct stat *);
 extern int v9fs_co_remove(V9fsState *, V9fsPath *);
 extern int v9fs_co_rename(V9fsState *, V9fsPath *, V9fsPath *);
+extern int v9fs_co_unlinkat(V9fsState *, V9fsPath *, V9fsString *, int flags);
 extern int v9fs_co_renameat(V9fsState *, V9fsPath *, V9fsString *,
                             V9fsPath *, V9fsString *);
 extern int v9fs_co_fstat(V9fsState *, int, struct stat *);
diff --git a/hw/9pfs/virtio-9p-local.c b/hw/9pfs/virtio-9p-local.c
index a38c619..37be2d5 100644
--- a/hw/9pfs/virtio-9p-local.c
+++ b/hw/9pfs/virtio-9p-local.c
@@ -631,6 +631,21 @@ static int local_renameat(FsContext *ctx, V9fsPath *olddir,
     return ret;
 }
 
+static int local_unlinkat(FsContext *ctx, V9fsPath *dir,
+                          const char *name, int flags)
+{
+    int ret;
+    V9fsString fullname;
+    char buffer[PATH_MAX];
+    v9fs_string_init(&fullname);
+
+    v9fs_string_sprintf(&fullname, "%s/%s", dir->data, name);
+    ret = remove(rpath(ctx, fullname.data, buffer));
+    v9fs_string_free(&fullname);
+
+    return ret;
+}
+
 FileOperations local_ops = {
     .lstat = local_lstat,
     .readlink = local_readlink,
@@ -664,4 +679,5 @@ FileOperations local_ops = {
     .lremovexattr = local_lremovexattr,
     .name_to_path = local_name_to_path,
     .renameat  = local_renameat,
+    .unlinkat = local_unlinkat,
 };
diff --git a/hw/9pfs/virtio-9p.c b/hw/9pfs/virtio-9p.c
index 9127873..bc77387 100644
--- a/hw/9pfs/virtio-9p.c
+++ b/hw/9pfs/virtio-9p.c
@@ -2378,6 +2378,49 @@ out_nofid:
     complete_pdu(pdu->s, pdu, err);
 }
 
+static void v9fs_unlinkat(void *opaque)
+{
+    int err = 0;
+    V9fsString name;
+    int32_t dfid, flags;
+    size_t offset = 7;
+    V9fsPath path;
+    V9fsFidState *dfidp;
+    V9fsPDU *pdu = opaque;
+
+    pdu_unmarshal(pdu, offset, "dsd", &dfid, &name, &flags);
+
+    dfidp = get_fid(pdu->s, dfid);
+    if (dfidp == NULL) {
+        err = -EINVAL;
+        goto out_nofid;
+    }
+    /*
+     * IF the file is unlinked, we cannot reopen
+     * the file later. So don't reclaim fd
+     */
+    v9fs_path_init(&path);
+    err = v9fs_co_name_to_path(pdu->s, &dfidp->path, name.data, &path);
+    if (err < 0) {
+        goto out_err;
+    }
+    err = v9fs_mark_fids_unreclaim(pdu->s, &path);
+    if (err < 0) {
+        goto out_err;
+    }
+    err = v9fs_co_unlinkat(pdu->s, &dfidp->path, &name, flags);
+    if (!err) {
+        err = offset;
+    }
+out_err:
+    put_fid(pdu->s, dfidp);
+    v9fs_path_free(&path);
+    v9fs_string_free(&name);
+out_nofid:
+    complete_pdu(pdu->s, pdu, err);
+}
+
+
 /* Only works with path name based fid */
 static int v9fs_complete_rename(V9fsState *s, V9fsFidState *fidp,
                                 int32_t newdirfid, V9fsString *name)
@@ -3058,6 +3101,7 @@ static CoroutineEntry *pdu_co_handlers[] = {
     [P9_TGETLOCK] = v9fs_getlock,
     [P9_TRENAMEAT] = v9fs_renameat,
     [P9_TREADLINK] = v9fs_readlink,
+    [P9_TUNLINKAT] = v9fs_unlinkat,
     [P9_TMKDIR] = v9fs_mkdir,
     [P9_TVERSION] = v9fs_version,
     [P9_TLOPEN] = v9fs_open,
diff --git a/hw/9pfs/virtio-9p.h b/hw/9pfs/virtio-9p.h
index 8156568..23a0a5e 100644
--- a/hw/9pfs/virtio-9p.h
+++ b/hw/9pfs/virtio-9p.h
@@ -54,6 +54,8 @@ enum {
     P9_RMKDIR,
     P9_TRENAMEAT = 74,
     P9_RRENAMEAT,
+    P9_TUNLINKAT = 76,
+    P9_RUNLINKAT,
     P9_TVERSION = 100,
     P9_RVERSION,
     P9_TAUTH = 102,
-- 
1.7.4.1