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Received: from viro by zeniv.linux.org.uk with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vDXqp-00000001eWT-2AS4; Tue, 28 Oct 2025 00:46:15 +0000 From: Al Viro To: linux-fsdevel@vger.kernel.org Cc: torvalds@linux-foundation.org, brauner@kernel.org, jack@suse.cz, raven@themaw.net, miklos@szeredi.hu, neil@brown.name, a.hindborg@kernel.org, linux-mm@kvack.org, linux-efi@vger.kernel.org, ocfs2-devel@lists.linux.dev, kees@kernel.org, rostedt@goodmis.org, gregkh@linuxfoundation.org, linux-usb@vger.kernel.org, paul@paul-moore.com, casey@schaufler-ca.com, linuxppc-dev@lists.ozlabs.org, john.johansen@canonical.com, selinux@vger.kernel.org, borntraeger@linux.ibm.com, bpf@vger.kernel.org Subject: [PATCH v2 08/50] convert ramfs and tmpfs Date: Tue, 28 Oct 2025 00:45:27 +0000 Message-ID: <20251028004614.393374-9-viro@zeniv.linux.org.uk> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20251028004614.393374-1-viro@zeniv.linux.org.uk> References: <20251028004614.393374-1-viro@zeniv.linux.org.uk> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam01 X-Stat-Signature: crj116nk3at319r3894fimsg3mnyqm85 X-Rspam-User: X-Rspamd-Queue-Id: 0F689140003 X-HE-Tag: 1761612383-854630 X-HE-Meta: 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 /7pbrhFY YiKapaOB3rtwriQoDiRgIwRj4h5vKp1aYOvD5GfgiPPZUWnQoMA7cvKQSqxSVjXRWjTs5qLShYVSoivZTP1Tl8X3RulDbGeBD+KNxmaYOxzb4nPsofFDa93XTtPzwe9BLLU2X2BbJm4uUNDERFBhB3v2iyiWY4k4UFZI4H9h3Rub6JzGhG3fY4YP5QqGF6/0jeXH+3eXOtgHtblZGmjDuzMr7e9jjtIc+15s4oK0YWfqupsIJoYmUv8hcowGVSqemcYAbxgqu3DYO6UJr/R3nRfogGfmgNyvc7NhtuFxXYmaAjEGKQxMKDV9A62r8dG5ZUtsxDUGQuvu6G3tZ96wD8zxaQfjLYDGGzUvfHWAzFFkXaL3TgrLlaVQogKgpdCHPX5TZRFa25eLdzkjRDp7ccEIg5zMpzFtjjIW/ X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Quite a bit is already done by infrastructure changes (simple_link(), simple_unlink()) - all that is left is replacing d_instantiate() + pinning dget() (in ->symlink() and ->mknod()) with d_make_persistent(), and, in case of shmem, using simple_unlink() and simple_link() in ->unlink() and ->link() resp., instead of open-coding those there. Since d_make_persistent() accepts (and hashes) unhashed ones, shmem situation gets simpler - we no longer care whether ->lookup() has hashed the sucker. With that done, we don't need kill_litter_super() for these filesystems anymore - by the umount time all remaining dentries will be marked persistent and kill_litter_super() will boil down to call of kill_anon_super(). The same goes for devtmpfs and rootfs - they are handled by ramfs or by shmem, depending upon config. NB: strictly speaking, both devtmpfs and rootfs ought to use ramfs_kill_sb() if they end up using ramfs; that's a separate story and the only impact of "just use kill_{litter,anon}_super()" is that we fail to free their sb->s_fs_info... on reboot. That's orthogonal to the changes in this series - kill_litter_super() is identical to kill_anon_super() for those at this point. Signed-off-by: Al Viro --- drivers/base/devtmpfs.c | 2 +- fs/ramfs/inode.c | 8 +++----- init/do_mounts.c | 2 +- mm/shmem.c | 38 ++++++++------------------------------ 4 files changed, 13 insertions(+), 37 deletions(-) diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c index 9d4e46ad8352..a63b0ff0c432 100644 --- a/drivers/base/devtmpfs.c +++ b/drivers/base/devtmpfs.c @@ -70,7 +70,7 @@ static struct file_system_type internal_fs_type = { #else .init_fs_context = ramfs_init_fs_context, #endif - .kill_sb = kill_litter_super, + .kill_sb = kill_anon_super, }; /* Simply take a ref on the existing mount */ diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c index 41f9995da7ca..505d10a0cb36 100644 --- a/fs/ramfs/inode.c +++ b/fs/ramfs/inode.c @@ -110,8 +110,7 @@ ramfs_mknod(struct mnt_idmap *idmap, struct inode *dir, goto out; } - d_instantiate(dentry, inode); - dget(dentry); /* Extra count - pin the dentry in core */ + d_make_persistent(dentry, inode); error = 0; inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir)); } @@ -154,8 +153,7 @@ static int ramfs_symlink(struct mnt_idmap *idmap, struct inode *dir, error = page_symlink(inode, symname, l); if (!error) { - d_instantiate(dentry, inode); - dget(dentry); + d_make_persistent(dentry, inode); inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir)); } else @@ -313,7 +311,7 @@ int ramfs_init_fs_context(struct fs_context *fc) void ramfs_kill_sb(struct super_block *sb) { kfree(sb->s_fs_info); - kill_litter_super(sb); + kill_anon_super(sb); } static struct file_system_type ramfs_fs_type = { diff --git a/init/do_mounts.c b/init/do_mounts.c index 6af29da8889e..810878fb55b6 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -507,7 +507,7 @@ static int rootfs_init_fs_context(struct fs_context *fc) struct file_system_type rootfs_fs_type = { .name = "rootfs", .init_fs_context = rootfs_init_fs_context, - .kill_sb = kill_litter_super, + .kill_sb = kill_anon_super, }; void __init init_rootfs(void) diff --git a/mm/shmem.c b/mm/shmem.c index b9081b817d28..a38f71519813 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -3858,12 +3858,7 @@ shmem_mknod(struct mnt_idmap *idmap, struct inode *dir, inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir)); inode_inc_iversion(dir); - if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir)) - d_add(dentry, inode); - else - d_instantiate(dentry, inode); - - dget(dentry); /* Extra count - pin the dentry in core */ + d_make_persistent(dentry, inode); return error; out_iput: @@ -3924,7 +3919,7 @@ static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) { struct inode *inode = d_inode(old_dentry); - int ret = 0; + int ret; /* * No ordinary (disk based) filesystem counts links as inodes; @@ -3936,29 +3931,19 @@ static int shmem_link(struct dentry *old_dentry, struct inode *dir, if (inode->i_nlink) { ret = shmem_reserve_inode(inode->i_sb, NULL); if (ret) - goto out; + return ret; } ret = simple_offset_add(shmem_get_offset_ctx(dir), dentry); if (ret) { if (inode->i_nlink) shmem_free_inode(inode->i_sb, 0); - goto out; + return ret; } dir->i_size += BOGO_DIRENT_SIZE; - inode_set_mtime_to_ts(dir, - inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode))); inode_inc_iversion(dir); - inc_nlink(inode); - ihold(inode); /* New dentry reference */ - dget(dentry); /* Extra pinning count for the created dentry */ - if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir)) - d_add(dentry, inode); - else - d_instantiate(dentry, inode); -out: - return ret; + return simple_link(old_dentry, dir, dentry); } static int shmem_unlink(struct inode *dir, struct dentry *dentry) @@ -3971,11 +3956,8 @@ static int shmem_unlink(struct inode *dir, struct dentry *dentry) simple_offset_remove(shmem_get_offset_ctx(dir), dentry); dir->i_size -= BOGO_DIRENT_SIZE; - inode_set_mtime_to_ts(dir, - inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode))); inode_inc_iversion(dir); - drop_nlink(inode); - dput(dentry); /* Undo the count from "create" - does all the work */ + simple_unlink(dir, dentry); /* * For now, VFS can't deal with case-insensitive negative dentries, so @@ -4130,11 +4112,7 @@ static int shmem_symlink(struct mnt_idmap *idmap, struct inode *dir, dir->i_size += BOGO_DIRENT_SIZE; inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir)); inode_inc_iversion(dir); - if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir)) - d_add(dentry, inode); - else - d_instantiate(dentry, inode); - dget(dentry); + d_make_persistent(dentry, inode); return 0; out_remove_offset: @@ -5334,7 +5312,7 @@ static struct file_system_type shmem_fs_type = { #ifdef CONFIG_TMPFS .parameters = shmem_fs_parameters, #endif - .kill_sb = kill_litter_super, + .kill_sb = kill_anon_super, .fs_flags = FS_USERNS_MOUNT | FS_ALLOW_IDMAP | FS_MGTIME, }; -- 2.47.3