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Message-Id: <20250421013346.32530-15-john@groves.net>
Date: Sun, 20 Apr 2025 20:33:41 -0500
From: John Groves <John@...ves.net>
To: John Groves <John@...ves.net>,
Dan Williams <dan.j.williams@...el.com>,
Miklos Szeredi <miklos@...redb.hu>,
Bernd Schubert <bschubert@....com>
Cc: John Groves <jgroves@...ron.com>,
Jonathan Corbet <corbet@....net>,
Vishal Verma <vishal.l.verma@...el.com>,
Dave Jiang <dave.jiang@...el.com>,
Matthew Wilcox <willy@...radead.org>,
Jan Kara <jack@...e.cz>,
Alexander Viro <viro@...iv.linux.org.uk>,
Christian Brauner <brauner@...nel.org>,
"Darrick J . Wong" <djwong@...nel.org>,
Luis Henriques <luis@...lia.com>,
Randy Dunlap <rdunlap@...radead.org>,
Jeff Layton <jlayton@...nel.org>,
Kent Overstreet <kent.overstreet@...ux.dev>,
Petr Vorel <pvorel@...e.cz>,
Brian Foster <bfoster@...hat.com>,
linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org,
nvdimm@...ts.linux.dev,
linux-cxl@...r.kernel.org,
linux-fsdevel@...r.kernel.org,
Amir Goldstein <amir73il@...il.com>,
Jonathan Cameron <Jonathan.Cameron@...wei.com>,
Stefan Hajnoczi <shajnocz@...hat.com>,
Joanne Koong <joannelkoong@...il.com>,
Josef Bacik <josef@...icpanda.com>,
Aravind Ramesh <arramesh@...ron.com>,
Ajay Joshi <ajayjoshi@...ron.com>,
John Groves <john@...ves.net>
Subject: [RFC PATCH 14/19] famfs_fuse: GET_DAXDEV message and daxdev_table
* The new GET_DAXDEV message/response is enabled
* The command it triggered by the update_daxdev_table() call, if there
are any daxdevs in the subject fmap that are not represented in the
daxdev_dable yet.
Signed-off-by: John Groves <john@...ves.net>
---
fs/fuse/famfs.c | 281 ++++++++++++++++++++++++++++++++++++--
fs/fuse/famfs_kfmap.h | 23 ++++
fs/fuse/fuse_i.h | 4 +
fs/fuse/inode.c | 2 +
fs/namei.c | 1 +
include/uapi/linux/fuse.h | 15 ++
6 files changed, 316 insertions(+), 10 deletions(-)
diff --git a/fs/fuse/famfs.c b/fs/fuse/famfs.c
index e62c047d0950..2e182cb7d7c9 100644
--- a/fs/fuse/famfs.c
+++ b/fs/fuse/famfs.c
@@ -20,6 +20,250 @@
#include "famfs_kfmap.h"
#include "fuse_i.h"
+/*
+ * famfs_teardown()
+ *
+ * Deallocate famfs metadata for a fuse_conn
+ */
+void
+famfs_teardown(struct fuse_conn *fc)
+{
+ struct famfs_dax_devlist *devlist = fc->dax_devlist;
+ int i;
+
+ fc->dax_devlist = NULL;
+
+ if (!devlist)
+ return;
+
+ if (!devlist->devlist)
+ goto out;
+
+ /* Close & release all the daxdevs in our table */
+ for (i = 0; i < devlist->nslots; i++) {
+ if (devlist->devlist[i].valid && devlist->devlist[i].devp)
+ fs_put_dax(devlist->devlist[i].devp, fc);
+ }
+ kfree(devlist->devlist);
+
+out:
+ kfree(devlist);
+}
+
+static int
+famfs_verify_daxdev(const char *pathname, dev_t *devno)
+{
+ struct inode *inode;
+ struct path path;
+ int err;
+
+ if (!pathname || !*pathname)
+ return -EINVAL;
+
+ err = kern_path(pathname, LOOKUP_FOLLOW, &path);
+ if (err)
+ return err;
+
+ inode = d_backing_inode(path.dentry);
+ if (!S_ISCHR(inode->i_mode)) {
+ err = -EINVAL;
+ goto out_path_put;
+ }
+
+ if (!may_open_dev(&path)) { /* had to export this */
+ err = -EACCES;
+ goto out_path_put;
+ }
+
+ *devno = inode->i_rdev;
+
+out_path_put:
+ path_put(&path);
+ return err;
+}
+
+/**
+ * famfs_fuse_get_daxdev()
+ *
+ * Send a GET_DAXDEV message to the fuse server to retrieve info on a
+ * dax device.
+ *
+ * @fm - fuse_mount
+ * @index - the index of the dax device; daxdevs are referred to by index
+ * in fmaps, and the server resolves the index to a particular daxdev
+ *
+ * Returns: 0=success
+ * -errno=failure
+ */
+static int
+famfs_fuse_get_daxdev(struct fuse_mount *fm, const u64 index)
+{
+ struct fuse_daxdev_out daxdev_out = { 0 };
+ struct fuse_conn *fc = fm->fc;
+ struct famfs_daxdev *daxdev;
+ int err = 0;
+
+ FUSE_ARGS(args);
+
+ pr_notice("%s: index=%lld\n", __func__, index);
+
+ /* Store the daxdev in our table */
+ if (index >= fc->dax_devlist->nslots) {
+ pr_err("%s: index(%lld) > nslots(%d)\n",
+ __func__, index, fc->dax_devlist->nslots);
+ err = -EINVAL;
+ goto out;
+ }
+
+ args.opcode = FUSE_GET_DAXDEV;
+ args.nodeid = index;
+
+ args.in_numargs = 0;
+
+ args.out_numargs = 1;
+ args.out_args[0].size = sizeof(daxdev_out);
+ args.out_args[0].value = &daxdev_out;
+
+ /* Send GET_DAXDEV command */
+ err = fuse_simple_request(fm, &args);
+ if (err) {
+ pr_err("%s: err=%d from fuse_simple_request()\n",
+ __func__, err);
+ /* Error will be that the payload is smaller than FMAP_BUFSIZE,
+ * which is the max we can handle. Empty payload handled below.
+ */
+ goto out;
+ }
+
+ down_write(&fc->famfs_devlist_sem);
+
+ daxdev = &fc->dax_devlist->devlist[index];
+ pr_debug("%s: dax_devlist %llx daxdev[%lld]=%llx\n", __func__,
+ (u64)fc->dax_devlist, index, (u64)daxdev);
+
+ /* Abort if daxdev is now valid */
+ if (daxdev->valid) {
+ up_write(&fc->famfs_devlist_sem);
+ /* We already have a valid entry at this index */
+ err = -EALREADY;
+ goto out;
+ }
+
+ /* This verifies that the dev is valid and can be opened and gets the devno */
+ pr_debug("%s: famfs_verify_daxdev(%s)\n", __func__, daxdev_out.name);
+ err = famfs_verify_daxdev(daxdev_out.name, &daxdev->devno);
+ if (err) {
+ up_write(&fc->famfs_devlist_sem);
+ pr_err("%s: err=%d from famfs_verify_daxdev()\n", __func__, err);
+ goto out;
+ }
+
+ /* This will fail if it's not a dax device */
+ pr_debug("%s: dax_dev_get(%x)\n", __func__, daxdev->devno);
+ daxdev->devp = dax_dev_get(daxdev->devno);
+ if (!daxdev->devp) {
+ up_write(&fc->famfs_devlist_sem);
+ pr_warn("%s: device %s not found or not dax\n",
+ __func__, daxdev_out.name);
+ err = -ENODEV;
+ goto out;
+ }
+
+ daxdev->name = kstrdup(daxdev_out.name, GFP_KERNEL);
+ wmb(); /* all daxdev fields must be visible before marking it valid */
+ daxdev->valid = 1;
+
+ up_write(&fc->famfs_devlist_sem);
+
+ pr_debug("%s: daxdev(%lld, %s)=%llx opened and marked valid\n",
+ __func__, index, daxdev->name, (u64)daxdev);
+
+out:
+ return err;
+}
+
+/**
+ * famfs_update_daxdev_table()
+ *
+ * This function is called for each new file fmap, to verify whether all
+ * referenced daxdevs are already known (i.e. in the table). Any daxdev
+ * indices that are not in the table will be retrieved via
+ * famfs_fuse_get_daxdev()
+ * @fm - fuse_mount
+ * @meta - famfs_file_meta, in-memory format, built from a GET_FMAP response
+ *
+ * Returns: 0=success
+ * -errno=failure
+ */
+static int
+famfs_update_daxdev_table(
+ struct fuse_mount *fm,
+ const struct famfs_file_meta *meta)
+{
+ struct famfs_dax_devlist *local_devlist;
+ struct fuse_conn *fc = fm->fc;
+ int err;
+ int i;
+
+ pr_debug("%s: dev_bitmap=0x%llx\n", __func__, meta->dev_bitmap);
+
+ /* First time through we will need to allocate the dax_devlist */
+ if (!fc->dax_devlist) {
+ local_devlist = kcalloc(1, sizeof(*fc->dax_devlist), GFP_KERNEL);
+ if (!local_devlist)
+ return -ENOMEM;
+
+ local_devlist->nslots = MAX_DAXDEVS;
+ pr_debug("%s: allocate dax_devlist=%llx\n", __func__,
+ (u64)local_devlist);
+
+ local_devlist->devlist = kcalloc(MAX_DAXDEVS,
+ sizeof(struct famfs_daxdev),
+ GFP_KERNEL);
+ if (!local_devlist->devlist) {
+ kfree(local_devlist);
+ return -ENOMEM;
+ }
+
+ /* We don't need the famfs_devlist_sem here because we use cmpxchg... */
+ if (cmpxchg(&fc->dax_devlist, NULL, local_devlist) != NULL) {
+ pr_debug("%s: aborting new devlist\n", __func__);
+ kfree(local_devlist->devlist);
+ kfree(local_devlist); /* another thread beat us to it */
+ } else {
+ pr_debug("%s: published new dax_devlist %llx / %llx\n",
+ __func__, (u64)local_devlist,
+ (u64)local_devlist->devlist);
+ }
+ }
+
+ down_read(&fc->famfs_devlist_sem);
+ for (i = 0; i < fc->dax_devlist->nslots; i++) {
+ if (meta->dev_bitmap & (1ULL << i)) {
+ /* This file meta struct references devindex i
+ * if devindex i isn't in the table; get it...
+ */
+ if (!(fc->dax_devlist->devlist[i].valid)) {
+ up_read(&fc->famfs_devlist_sem);
+
+ pr_notice("%s: daxdev=%d (%llx) invalid...getting\n",
+ __func__, i,
+ (u64)(&fc->dax_devlist->devlist[i]));
+ err = famfs_fuse_get_daxdev(fm, i);
+ if (err)
+ pr_err("%s: failed to get daxdev=%d\n",
+ __func__, i);
+
+ down_read(&fc->famfs_devlist_sem);
+ }
+ }
+ }
+ up_read(&fc->famfs_devlist_sem);
+
+ return 0;
+}
+
+/***************************************************************************/
void
__famfs_meta_free(void *famfs_meta)
@@ -67,12 +311,15 @@ famfs_check_ext_alignment(struct famfs_meta_simple_ext *se)
}
/**
- * famfs_meta_alloc() - Allocate famfs file metadata
+ * famfs_fuse_meta_alloc() - Allocate famfs file metadata
* @metap: Pointer to an mcache_map_meta pointer
* @ext_count: The number of extents needed
+ *
+ * Returns: 0=success
+ * -errno=failure
*/
static int
-famfs_meta_alloc_v3(
+famfs_fuse_meta_alloc(
void *fmap_buf,
size_t fmap_buf_size,
struct famfs_file_meta **metap)
@@ -92,28 +339,25 @@ famfs_meta_alloc_v3(
if (next_offset > fmap_buf_size) {
pr_err("%s:%d: fmap_buf underflow offset/size %ld/%ld\n",
__func__, __LINE__, next_offset, fmap_buf_size);
- rc = -EINVAL;
- goto errout;
+ return -EINVAL;
}
if (fmh->nextents < 1) {
pr_err("%s: nextents %d < 1\n", __func__, fmh->nextents);
- rc = -EINVAL;
- goto errout;
+ return -EINVAL;
}
if (fmh->nextents > FUSE_FAMFS_MAX_EXTENTS) {
pr_err("%s: nextents %d > max (%d) 1\n",
__func__, fmh->nextents, FUSE_FAMFS_MAX_EXTENTS);
- rc = -E2BIG;
- goto errout;
+ return -E2BIG;
}
meta = kzalloc(sizeof(*meta), GFP_KERNEL);
if (!meta)
return -ENOMEM;
- meta->error = false;
+ meta->error = false;
meta->file_type = fmh->file_type;
meta->file_size = fmh->file_size;
meta->fm_extent_type = fmh->ext_type;
@@ -298,6 +542,20 @@ famfs_meta_alloc_v3(
return rc;
}
+/**
+ * famfs_file_init_dax()
+ *
+ * Initialize famfs metadata for a file, based on the contents of the GET_FMAP
+ * response
+ *
+ * @fm - fuse_mount
+ * @inode - the inode
+ * @fmap_buf - fmap response message
+ * @fmap_size - Size of the fmap message
+ *
+ * Returns: 0=success
+ * -errno=failure
+ */
int
famfs_file_init_dax(
struct fuse_mount *fm,
@@ -316,10 +574,13 @@ famfs_file_init_dax(
return -EEXIST;
}
- rc = famfs_meta_alloc_v3(fmap_buf, fmap_size, &meta);
+ rc = famfs_fuse_meta_alloc(fmap_buf, fmap_size, &meta);
if (rc)
goto errout;
+ /* Make sure this fmap doesn't reference any unknown daxdevs */
+ famfs_update_daxdev_table(fm, meta);
+
/* Publish the famfs metadata on fi->famfs_meta */
inode_lock(inode);
if (fi->famfs_meta) {
diff --git a/fs/fuse/famfs_kfmap.h b/fs/fuse/famfs_kfmap.h
index ce785d76719c..325adb8b99c5 100644
--- a/fs/fuse/famfs_kfmap.h
+++ b/fs/fuse/famfs_kfmap.h
@@ -60,4 +60,27 @@ struct famfs_file_meta {
};
};
+/*
+ * dax_devlist
+ *
+ * This is the in-memory daxdev metadata that is populated by
+ * the responses to GET_FMAP messages
+ */
+struct famfs_daxdev {
+ /* Include dev uuid? */
+ bool valid;
+ bool error;
+ dev_t devno;
+ struct dax_device *devp;
+ char *name;
+};
+
+#define MAX_DAXDEVS 24
+
+struct famfs_dax_devlist {
+ int nslots;
+ int ndevs;
+ struct famfs_daxdev *devlist; /* XXX: make this an xarray! */
+};
+
#endif /* FAMFS_KFMAP_H */
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index d8e0ac784224..4c4c4f0ff280 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1561,7 +1561,11 @@ extern void fuse_sysctl_unregister(void);
int famfs_file_init_dax(struct fuse_mount *fm,
struct inode *inode, void *fmap_buf,
size_t fmap_size);
+ssize_t famfs_dax_write_iter(struct kiocb *iocb, struct iov_iter *from);
+ssize_t famfs_dax_read_iter(struct kiocb *iocb, struct iov_iter *to);
+int famfs_file_mmap(struct file *file, struct vm_area_struct *vma);
void __famfs_meta_free(void *map);
+void famfs_teardown(struct fuse_conn *fc);
#endif
static inline struct fuse_backing *famfs_meta_set(struct fuse_inode *fi,
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index e86bf330117f..af1629b07a30 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1051,6 +1051,8 @@ void fuse_conn_put(struct fuse_conn *fc)
}
if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
fuse_backing_files_free(fc);
+ if (IS_ENABLED(CONFIG_FUSE_FAMFS_DAX))
+ famfs_teardown(fc);
call_rcu(&fc->rcu, delayed_release);
}
}
diff --git a/fs/namei.c b/fs/namei.c
index ecb7b95c2ca3..75a1e1d46593 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3380,6 +3380,7 @@ bool may_open_dev(const struct path *path)
return !(path->mnt->mnt_flags & MNT_NODEV) &&
!(path->mnt->mnt_sb->s_iflags & SB_I_NODEV);
}
+EXPORT_SYMBOL(may_open_dev);
static int may_open(struct mnt_idmap *idmap, const struct path *path,
int acc_mode, int flag)
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 0f6ff1ffb23d..982d4fc66ef8 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -1328,4 +1328,19 @@ struct fuse_famfs_fmap_header {
uint64_t file_size;
uint64_t reserved1;
};
+
+struct fuse_get_daxdev_in {
+ uint32_t daxdev_num;
+};
+
+#define DAXDEV_NAME_MAX 256
+struct fuse_daxdev_out {
+ uint16_t index;
+ uint16_t reserved;
+ uint32_t reserved2;
+ uint64_t reserved3; /* enough space for a uuid if we need it */
+ uint64_t reserved4;
+ char name[DAXDEV_NAME_MAX];
+};
+
#endif /* _LINUX_FUSE_H */
--
2.49.0
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