From: Al Viro <viro@zeniv.linux.org.uk>
To: yulei.kernel@gmail.com
Cc: akpm@linux-foundation.org, naoya.horiguchi@nec.com,
pbonzini@redhat.com, linux-fsdevel@vger.kernel.org,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
xiaoguangrong.eric@gmail.com, kernellwp@gmail.com,
lihaiwei.kernel@gmail.com, Yulei Zhang <yuleixzhang@tencent.com>,
Xiao Guangrong <gloryxiao@tencent.com>
Subject: Re: [PATCH 01/35] fs: introduce dmemfs module
Date: Tue, 10 Nov 2020 20:04:11 +0000 [thread overview]
Message-ID: <20201110200411.GU3576660@ZenIV.linux.org.uk> (raw)
In-Reply-To: <aa553faf9e97ee9306ecd5a67d3324a34f9ed4be.1602093760.git.yuleixzhang@tencent.com>
On Thu, Oct 08, 2020 at 03:53:51PM +0800, yulei.kernel@gmail.com wrote:
> +static struct inode *
> +dmemfs_get_inode(struct super_block *sb, const struct inode *dir, umode_t mode,
> + dev_t dev);
WTF is 'dev' for?
> +static int
> +dmemfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
> +{
> + struct inode *inode = dmemfs_get_inode(dir->i_sb, dir, mode, dev);
> + int error = -ENOSPC;
> +
> + if (inode) {
> + d_instantiate(dentry, inode);
> + dget(dentry); /* Extra count - pin the dentry in core */
> + error = 0;
> + dir->i_mtime = dir->i_ctime = current_time(inode);
> + }
> + return error;
> +}
... same here, seeing that you only call that thing from the next two functions
and you do *not* provide ->mknod() as a method (unsurprisingly - what would
device nodes do there?)
> +static int dmemfs_create(struct inode *dir, struct dentry *dentry,
> + umode_t mode, bool excl)
> +{
> + return dmemfs_mknod(dir, dentry, mode | S_IFREG, 0);
> +}
> +
> +static int dmemfs_mkdir(struct inode *dir, struct dentry *dentry,
> + umode_t mode)
> +{
> + int retval = dmemfs_mknod(dir, dentry, mode | S_IFDIR, 0);
> +
> + if (!retval)
> + inc_nlink(dir);
> + return retval;
> +}
> +int dmemfs_file_mmap(struct file *file, struct vm_area_struct *vma)
> +{
> + return 0;
> +}
> +
> +static const struct file_operations dmemfs_file_operations = {
> + .mmap = dmemfs_file_mmap,
> +};
Er... Is that a placeholder for later in the series? Because as it is,
it makes no sense whatsoever - "it can be mmapped, but any access to the
mapped area will segfault".
> +struct inode *dmemfs_get_inode(struct super_block *sb,
> + const struct inode *dir, umode_t mode, dev_t dev)
> +{
> + struct inode *inode = new_inode(sb);
> +
> + if (inode) {
> + inode->i_ino = get_next_ino();
> + inode_init_owner(inode, dir, mode);
> + inode->i_mapping->a_ops = &empty_aops;
> + mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
> + mapping_set_unevictable(inode->i_mapping);
> + inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
> + switch (mode & S_IFMT) {
> + default:
> + init_special_inode(inode, mode, dev);
> + break;
> + case S_IFREG:
> + inode->i_op = &dmemfs_file_inode_operations;
> + inode->i_fop = &dmemfs_file_operations;
> + break;
> + case S_IFDIR:
> + inode->i_op = &dmemfs_dir_inode_operations;
> + inode->i_fop = &simple_dir_operations;
> +
> + /*
> + * directory inodes start off with i_nlink == 2
> + * (for "." entry)
> + */
> + inc_nlink(inode);
> + break;
> + case S_IFLNK:
> + inode->i_op = &page_symlink_inode_operations;
> + break;
Where would symlinks come from? Or anything other than regular files and
directories, for that matter...
next prev parent reply other threads:[~2020-11-10 20:04 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-08 7:53 [PATCH 00/35] Enhance memory utilization with DMEMFS yulei.kernel
2020-10-08 7:53 ` [PATCH 01/35] fs: introduce dmemfs module yulei.kernel
2020-11-10 20:04 ` Al Viro [this message]
2020-11-11 8:53 ` yulei zhang
2020-11-11 23:09 ` Al Viro
2020-11-12 10:03 ` yulei zhang
2020-10-08 7:53 ` [PATCH 02/35] mm: support direct memory reservation yulei.kernel
2020-10-08 20:27 ` Randy Dunlap
2020-10-08 20:34 ` Randy Dunlap
2020-10-08 7:53 ` [PATCH 03/35] dmem: implement dmem memory management yulei.kernel
2020-10-08 7:53 ` [PATCH 04/35] dmem: let pat recognize dmem yulei.kernel
2020-10-13 7:27 ` Paolo Bonzini
2020-10-13 9:53 ` yulei zhang
2020-10-08 7:53 ` [PATCH 05/35] dmemfs: support mmap yulei.kernel
2020-10-08 7:53 ` [PATCH 06/35] dmemfs: support truncating inode down yulei.kernel
2020-10-08 7:53 ` [PATCH 07/35] dmem: trace core functions yulei.kernel
2020-10-08 7:53 ` [PATCH 08/35] dmem: show some statistic in debugfs yulei.kernel
2020-10-08 20:23 ` Randy Dunlap
2020-10-09 11:49 ` yulei zhang
2020-10-08 7:53 ` [PATCH 09/35] dmemfs: support remote access yulei.kernel
2020-10-08 7:54 ` [PATCH 10/35] dmemfs: introduce max_alloc_try_dpages parameter yulei.kernel
2020-10-08 7:54 ` [PATCH 11/35] mm: export mempolicy interfaces to serve dmem allocator yulei.kernel
2020-10-08 7:54 ` [PATCH 12/35] dmem: introduce mempolicy support yulei.kernel
2020-10-08 7:54 ` [PATCH 13/35] mm, dmem: introduce PFN_DMEM and pfn_t_dmem yulei.kernel
2020-10-08 7:54 ` [PATCH 14/35] mm, dmem: dmem-pmd vs thp-pmd yulei.kernel
2020-10-08 7:54 ` [PATCH 15/35] mm: add pmd_special() check for pmd_trans_huge_lock() yulei.kernel
2020-10-08 7:54 ` [PATCH 16/35] dmemfs: introduce ->split() to dmemfs_vm_ops yulei.kernel
2020-10-08 7:54 ` [PATCH 17/35] mm, dmemfs: support unmap_page_range() for dmemfs pmd yulei.kernel
2020-10-08 7:54 ` [PATCH 18/35] mm: follow_pmd_mask() for dmem huge pmd yulei.kernel
2020-10-08 7:54 ` [PATCH 19/35] mm: gup_huge_pmd() " yulei.kernel
2020-10-08 7:54 ` [PATCH 20/35] mm: support dmem huge pmd for vmf_insert_pfn_pmd() yulei.kernel
2020-10-08 7:54 ` [PATCH 21/35] mm: support dmem huge pmd for follow_pfn() yulei.kernel
2020-10-08 7:54 ` [PATCH 22/35] kvm, x86: Distinguish dmemfs page from mmio page yulei.kernel
2020-10-09 0:58 ` Sean Christopherson
2020-10-09 10:28 ` Joao Martins
2020-10-09 11:42 ` yulei zhang
2020-10-08 7:54 ` [PATCH 23/35] kvm, x86: introduce VM_DMEM yulei.kernel
2020-10-08 7:54 ` [PATCH 24/35] dmemfs: support hugepage for dmemfs yulei.kernel
2020-10-08 7:54 ` [PATCH 25/35] mm, x86, dmem: fix estimation of reserved page for vaddr_get_pfn() yulei.kernel
2020-10-08 7:54 ` [PATCH 26/35] mm, dmem: introduce pud_special() yulei.kernel
2020-10-08 7:54 ` [PATCH 27/35] mm: add pud_special() to support dmem huge pud yulei.kernel
2020-10-08 7:54 ` [PATCH 28/35] mm, dmemfs: support huge_fault() for dmemfs yulei.kernel
2020-10-08 7:54 ` [PATCH 29/35] mm: add follow_pte_pud() yulei.kernel
2020-10-08 7:54 ` [PATCH 30/35] dmem: introduce dmem_bitmap_alloc() and dmem_bitmap_free() yulei.kernel
2020-10-08 7:54 ` [PATCH 31/35] dmem: introduce mce handler yulei.kernel
2020-10-08 7:54 ` [PATCH 32/35] mm, dmemfs: register and handle the dmem mce yulei.kernel
2020-10-08 7:54 ` [PATCH 33/35] kvm, x86: temporary disable record_steal_time for dmem yulei.kernel
2020-10-08 7:54 ` [PATCH 34/35] dmem: add dmem unit tests yulei.kernel
2020-10-08 7:54 ` [PATCH 35/35] Add documentation for dmemfs yulei.kernel
2020-10-09 1:26 ` Randy Dunlap
2020-10-08 19:01 ` [PATCH 00/35] Enhance memory utilization with DMEMFS Joao Martins
2020-10-09 11:39 ` yulei zhang
2020-10-09 11:53 ` Joao Martins
2020-10-10 8:15 ` yulei zhang
2020-10-12 10:59 ` Joao Martins
2020-10-14 22:25 ` Dan Williams
2020-10-19 13:37 ` Paolo Bonzini
2020-10-19 19:03 ` Joao Martins
2020-10-20 15:22 ` yulei zhang
2020-10-12 11:57 ` Zengtao (B)
2020-10-13 2:45 ` yulei zhang
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