From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
To: John Groves <John@Groves.net>
Cc: John Groves <jgroves@micron.com>,
Jonathan Corbet <corbet@lwn.net>,
"Dan Williams" <dan.j.williams@intel.com>,
Vishal Verma <vishal.l.verma@intel.com>,
Dave Jiang <dave.jiang@intel.com>,
"Alexander Viro" <viro@zeniv.linux.org.uk>,
Christian Brauner <brauner@kernel.org>, "Jan Kara" <jack@suse.cz>,
Matthew Wilcox <willy@infradead.org>, <linux-cxl@vger.kernel.org>,
<linux-fsdevel@vger.kernel.org>, <linux-doc@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <nvdimm@lists.linux.dev>,
<john@jagalactic.com>, Dave Chinner <david@fromorbit.com>,
Christoph Hellwig <hch@infradead.org>,
<dave.hansen@linux.intel.com>, <gregory.price@memverge.com>
Subject: Re: [RFC PATCH 15/20] famfs: Add ioctl to file_operations
Date: Mon, 26 Feb 2024 13:44:08 +0000 [thread overview]
Message-ID: <20240226134408.00005576@Huawei.com> (raw)
In-Reply-To: <a5d0969403ca02af6593b6789a21b230b2436800.1708709155.git.john@groves.net>
On Fri, 23 Feb 2024 11:41:59 -0600
John Groves <John@Groves.net> wrote:
> This commit introduces the per-file ioctl function famfs_file_ioctl()
> into struct file_operations, and introduces the famfs_file_init_dax()
> function (which is called by famfs_file_ioct())
>
> famfs_file_init_dax() associates a dax extent list with a file, making
> it into a proper famfs file. It is called from the FAMFSIOC_MAP_CREATE
> ioctl. Starting with an empty file (which is basically a ramfs file),
> this turns the file into a DAX file backed by the specified extent list.
>
> The other ioctls are:
>
> FAMFSIOC_NOP - A convenient way for user space to verify it's a famfs file
> FAMFSIOC_MAP_GET - Get the header of the metadata for a file
> FAMFSIOC_MAP_GETEXT - Get the extents for a file
>
> The latter two, together, are comparable to xfs_bmap. Our user space tools
> use them primarly in testing.
>
> Signed-off-by: John Groves <john@groves.net>
A few more comments inline. Nothing fundamental just nice to have
simplifications of the code.
> ---
> fs/famfs/famfs_file.c | 226 ++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 226 insertions(+)
>
> diff --git a/fs/famfs/famfs_file.c b/fs/famfs/famfs_file.c
> index 5228e9de1e3b..fd42d5966982 100644
> --- a/fs/famfs/famfs_file.c
> +++ b/fs/famfs/famfs_file.c
> @@ -19,6 +19,231 @@
> #include <uapi/linux/famfs_ioctl.h>
> #include "famfs_internal.h"
>
> +/**
> + * famfs_map_meta_alloc() - Allocate famfs file metadata
> + * @mapp: Pointer to an mcache_map_meta pointer
> + * @ext_count: The number of extents needed
> + */
> +static int
> +famfs_meta_alloc(
> + struct famfs_file_meta **metap,
> + size_t ext_count)
> +{
> + struct famfs_file_meta *meta;
> + size_t metasz;
> +
> + *metap = NULL;
Not responsibility of caller?
> +
> + metasz = sizeof(*meta) + sizeof(*(meta->tfs_extents)) * ext_count;
Looks like struct_size() would be appropriate.
> +
> + meta = kzalloc(metasz, GFP_KERNEL);
> + if (!meta)
> + return -ENOMEM;
> +
> + meta->tfs_extent_ct = ext_count;
> + *metap = meta;
> +
> + return 0;
> +}
> +
> +static void
> +famfs_meta_free(
> + struct famfs_file_meta *map)
> +{
> + kfree(map);
Given this is just kfree you can use __free magic to simplify things below.
> +}
> +
> +/**
> + * famfs_file_init_dax() - FAMFSIOC_MAP_CREATE ioctl handler
> + * @file:
> + * @arg: ptr to struct mcioc_map in user space
> + *
> + * Setup the dax mapping for a file. Files are created empty, and then function is called
> + * (by famfs_file_ioctl()) to setup the mapping and set the file size.
> + */
> +static int
> +famfs_file_init_dax(
> + struct file *file,
> + void __user *arg)
> +{
> + struct famfs_extent *tfs_extents = NULL;
> + struct famfs_file_meta *meta = NULL;
> + struct inode *inode;
> + struct famfs_ioc_map imap;
> + struct famfs_fs_info *fsi;
> + struct super_block *sb;
> + int alignment_errs = 0;
> + size_t extent_total = 0;
> + size_t ext_count;
> + int rc = 0;
> + int i;
> +
> + rc = copy_from_user(&imap, arg, sizeof(imap));
> + if (rc)
> + return -EFAULT;
> +
> + ext_count = imap.ext_list_count;
> + if (ext_count < 1) {
> + rc = -ENOSPC;
> + goto errout;
meta data not yet allocated.
return -ENOSPC;
> + }
> +
> + if (ext_count > FAMFS_MAX_EXTENTS) {
> + rc = -E2BIG;
> + goto errout;
return
> + }
> +
> + inode = file_inode(file);
> + if (!inode) {
> + rc = -EBADF;
> + goto errout;
return;
> + }
> + sb = inode->i_sb;
> + fsi = inode->i_sb->s_fs_info;
> +
> + tfs_extents = &imap.ext_list[0];
> +
> + rc = famfs_meta_alloc(&meta, ext_count);
> + if (rc)
> + goto errout;
return ...
only after this point should there be any
meta data to free on exit?
> +
> + meta->file_type = imap.file_type;
> + meta->file_size = imap.file_size;
> +
> + /* Fill in the internal file metadata structure */
> + for (i = 0; i < imap.ext_list_count; i++) {
> + size_t len;
> + off_t offset;
> +
> + offset = imap.ext_list[i].offset;
> + len = imap.ext_list[i].len;
> +
> + extent_total += len;
> +
> + if (WARN_ON(offset == 0 && meta->file_type != FAMFS_SUPERBLOCK)) {
> + rc = -EINVAL;
> + goto errout;
> + }
> +
> + meta->tfs_extents[i].offset = offset;
> + meta->tfs_extents[i].len = len;
> +
> + /* All extent addresses/offsets must be 2MiB aligned,
> + * and all but the last length must be a 2MiB multiple.
> + */
> + if (!IS_ALIGNED(offset, PMD_SIZE)) {
> + pr_err("%s: error ext %d hpa %lx not aligned\n",
> + __func__, i, offset);
> + alignment_errs++;
> + }
> + if (i < (imap.ext_list_count - 1) && !IS_ALIGNED(len, PMD_SIZE)) {
> + pr_err("%s: error ext %d length %ld not aligned\n",
> + __func__, i, len);
> + alignment_errs++;
> + }
> + }
> +
> + /*
> + * File size can be <= ext list size, since extent sizes are constrained
> + * to PMD multiples
> + */
> + if (imap.file_size > extent_total) {
> + pr_err("%s: file size %lld larger than ext list size %lld\n",
> + __func__, (u64)imap.file_size, (u64)extent_total);
> + rc = -EINVAL;
> + goto errout;
> + }
> +
> + if (alignment_errs > 0) {
> + pr_err("%s: there were %d alignment errors in the extent list\n",
> + __func__, alignment_errs);
> + rc = -EINVAL;
> + goto errout;
> + }
> +
> + /* Publish the famfs metadata on inode->i_private */
> + inode_lock(inode);
Easy to add a guard definition - maybe useful enough to bother as can then do
this which makes the error handling align with other cases.
scoped_guard(inode_sem, inode) {
if (inode->i_private) {
rc = -EEXIST;
goto errout;
}
inode->...
}
> + if (inode->i_private) {
> + rc = -EEXIST; /* file already has famfs metadata */
> + } else {
> + inode->i_private = meta;
You could use __free on the meta data and
inode->i_private = no_ptr_free(meta);
here. Then all your earlier error paths become direct returns.
> + i_size_write(inode, imap.file_size);
> + inode->i_flags |= S_DAX;
> + }
> + inode_unlock(inode);
> +
> + errout:
> + if (rc)
> + famfs_meta_free(meta);
A separate error path is going to be easier to follow as no if (rc)
> +
> + return rc;
> +}
> +
> +/**
> + * famfs_file_ioctl() - top-level famfs file ioctl handler
> + * @file:
> + * @cmd:
> + * @arg:
> + */
> +static
> +long
> +famfs_file_ioctl(
> + struct file *file,
> + unsigned int cmd,
> + unsigned long arg)
> +{
> + long rc;
> +
> + switch (cmd) {
> + case FAMFSIOC_NOP:
> + rc = 0;
return 0;
> + break;
> +
> + case FAMFSIOC_MAP_CREATE:
> + rc = famfs_file_init_dax(file, (void *)arg);
return famfs_file_init_dax()
> + break;
> +
> + case FAMFSIOC_MAP_GET: {
> + struct inode *inode = file_inode(file);
> + struct famfs_file_meta *meta = inode->i_private;
> + struct famfs_ioc_map umeta;
> +
> + memset(&umeta, 0, sizeof(umeta));
> +
> + if (meta) {
> + /* TODO: do more to harmonize these structures */
> + umeta.extent_type = meta->tfs_extent_type;
> + umeta.file_size = i_size_read(inode);
> + umeta.ext_list_count = meta->tfs_extent_ct;
> +
> + rc = copy_to_user((void __user *)arg, &umeta, sizeof(umeta));
> + if (rc)
> + pr_err("%s: copy_to_user returned %ld\n", __func__, rc);
> +
> + } else {
> + rc = -EINVAL;
> + }
Flip logic.
if (!meta)
return -EINVAL;
umeta ...
return 0;
> + }
> + break;
> + case FAMFSIOC_MAP_GETEXT: {
> + struct inode *inode = file_inode(file);
> + struct famfs_file_meta *meta = inode->i_private;
> +
> + if (meta)
> + rc = copy_to_user((void __user *)arg, meta->tfs_extents,
> + meta->tfs_extent_ct * sizeof(struct famfs_extent));
> + else
> + rc = -EINVAL;
if (!meta)
return -EINVAL;
return copy_to_user
> + }
> + break;
> + default:
> + rc = -ENOTTY;
return -ENOTTY;
> + break;
> + }
> +
> + return rc;
Early returns will simplify the flow for anyone reading this.
> +}
next prev parent reply other threads:[~2024-02-26 13:44 UTC|newest]
Thread overview: 106+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-23 17:41 [RFC PATCH 00/20] Introduce the famfs shared-memory file system John Groves
2024-02-23 17:41 ` [RFC PATCH 01/20] famfs: Documentation John Groves
2024-02-23 17:41 ` [RFC PATCH 02/20] dev_dax_iomap: Add fs_dax_get() func to prepare dax for fs-dax usage John Groves
2024-02-26 12:05 ` Jonathan Cameron
2024-02-26 15:00 ` John Groves
2024-02-23 17:41 ` [RFC PATCH 03/20] dev_dax_iomap: Move dax_pgoff_to_phys from device.c to bus.c since both need it now John Groves
2024-02-26 12:10 ` Jonathan Cameron
2024-02-26 15:13 ` John Groves
2024-02-23 17:41 ` [RFC PATCH 04/20] dev_dax_iomap: Save the kva from memremap John Groves
2024-02-26 12:21 ` Jonathan Cameron
2024-02-26 15:48 ` John Groves
2024-02-23 17:41 ` [RFC PATCH 05/20] dev_dax_iomap: Add dax_operations for use by fs-dax on devdax John Groves
2024-02-26 12:32 ` Jonathan Cameron
2024-02-26 16:09 ` John Groves
2024-02-23 17:41 ` [RFC PATCH 06/20] dev_dax_iomap: Add CONFIG_DEV_DAX_IOMAP kernel build parameter John Groves
2024-02-26 12:34 ` Jonathan Cameron
2024-02-26 16:12 ` John Groves
2024-02-23 17:41 ` [RFC PATCH 07/20] famfs: Add include/linux/famfs_ioctl.h John Groves
2024-02-24 1:39 ` Randy Dunlap
2024-02-24 2:23 ` John Groves
2024-02-24 3:27 ` Randy Dunlap
2024-02-24 23:32 ` John Groves
2024-02-24 23:40 ` Randy Dunlap
2024-02-26 12:39 ` Jonathan Cameron
2024-02-26 16:44 ` John Groves
2024-02-26 16:56 ` Jonathan Cameron
2024-02-26 18:04 ` John Groves
2024-02-23 17:41 ` [RFC PATCH 08/20] famfs: Add famfs_internal.h John Groves
2024-02-26 12:48 ` Jonathan Cameron
2024-02-26 17:35 ` John Groves
2024-02-27 10:28 ` Jonathan Cameron
2024-02-28 1:06 ` John Groves
2024-02-27 13:38 ` Christian Brauner
2024-02-27 14:12 ` John Groves
2024-02-23 17:41 ` [RFC PATCH 09/20] famfs: Add super_operations John Groves
2024-02-26 12:51 ` Jonathan Cameron
2024-02-26 21:47 ` John Groves
2024-02-27 10:34 ` Jonathan Cameron
2024-02-27 17:48 ` John Groves
2024-02-23 17:41 ` [RFC PATCH 10/20] famfs: famfs_open_device() & dax_holder_operations John Groves
2024-02-26 12:56 ` Jonathan Cameron
2024-02-26 22:22 ` John Groves
2024-02-27 13:39 ` Christian Brauner
2024-02-27 18:38 ` John Groves
2024-02-23 17:41 ` [RFC PATCH 11/20] famfs: Add fs_context_operations John Groves
2024-02-26 13:20 ` Jonathan Cameron
2024-02-26 22:43 ` John Groves
2024-02-27 13:41 ` Christian Brauner
2024-02-28 0:59 ` John Groves
2024-02-28 1:49 ` Randy Dunlap
2024-02-28 8:17 ` Christian Brauner
2024-02-28 10:07 ` Christian Brauner
2024-02-28 12:01 ` Christian Brauner
2024-02-23 17:41 ` [RFC PATCH 12/20] famfs: Add inode_operations and file_system_type John Groves
2024-02-26 13:25 ` Jonathan Cameron
2024-02-26 22:53 ` John Groves
2024-02-23 17:41 ` [RFC PATCH 13/20] famfs: Add iomap_ops John Groves
2024-02-26 13:30 ` Jonathan Cameron
2024-02-26 23:00 ` John Groves
2024-02-23 17:41 ` [RFC PATCH 14/20] famfs: Add struct file_operations John Groves
2024-02-26 13:32 ` Jonathan Cameron
2024-02-26 23:09 ` John Groves
2024-02-23 17:41 ` [RFC PATCH 15/20] famfs: Add ioctl to file_operations John Groves
2024-02-26 13:44 ` Jonathan Cameron [this message]
2024-02-23 17:42 ` [RFC PATCH 16/20] famfs: Add fault counters John Groves
2024-02-23 18:23 ` Dave Hansen
2024-02-23 19:56 ` John Groves
2024-02-23 20:04 ` Dan Williams
2024-02-23 20:39 ` John Groves
2024-02-23 21:19 ` Dave Hansen
2024-02-23 23:50 ` Dan Williams
2024-02-24 3:59 ` Matthew Wilcox
2024-02-24 4:30 ` Dan Williams
2024-02-23 17:42 ` [RFC PATCH 17/20] famfs: Add module stuff John Groves
2024-02-26 13:47 ` Jonathan Cameron
2024-02-27 22:15 ` John Groves
2024-02-23 17:42 ` [RFC PATCH 18/20] famfs: Support character dax via the dev_dax_iomap patch John Groves
2024-02-26 13:52 ` Jonathan Cameron
2024-02-27 22:27 ` John Groves
2024-02-23 17:42 ` [RFC PATCH 19/20] famfs: Update MAINTAINERS file John Groves
2024-02-23 17:42 ` [RFC PATCH 20/20] famfs: Add Kconfig and Makefile plumbing John Groves
2024-02-24 1:50 ` Randy Dunlap
2024-02-24 2:24 ` John Groves
2024-02-24 0:07 ` [RFC PATCH 00/20] Introduce the famfs shared-memory file system Luis Chamberlain
2024-02-26 13:27 ` John Groves
2024-02-26 15:53 ` Luis Chamberlain
2024-02-26 21:16 ` John Groves
2024-02-27 0:58 ` Luis Chamberlain
2024-02-27 2:05 ` John Groves
2024-02-29 2:15 ` Dave Chinner
2024-02-29 14:52 ` John Groves
2024-03-11 1:29 ` Dave Chinner
2024-02-29 6:52 ` Amir Goldstein
2024-02-29 22:16 ` John Groves
2024-05-17 9:55 ` Miklos Szeredi
2024-05-19 5:59 ` Amir Goldstein
2024-05-22 2:05 ` John Groves
2024-05-22 8:58 ` Miklos Szeredi
2024-05-22 10:16 ` Amir Goldstein
2024-05-22 11:28 ` Miklos Szeredi
2024-05-22 13:41 ` Amir Goldstein
2024-05-23 2:49 ` John Groves
2024-05-23 13:57 ` Miklos Szeredi
2024-05-24 0:47 ` John Groves
2024-05-24 7:55 ` Miklos Szeredi
2024-05-25 22:54 ` Dave Chinner
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