From patchwork Fri May 5 18:38:14 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever X-Patchwork-Id: 13232955 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AAC7CC77B7C for ; Fri, 5 May 2023 18:38:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233131AbjEESia (ORCPT ); Fri, 5 May 2023 14:38:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47124 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231730AbjEESi2 (ORCPT ); Fri, 5 May 2023 14:38:28 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 28C761436C for ; Fri, 5 May 2023 11:38:27 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id B22F8612BE for ; Fri, 5 May 2023 18:38:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C8C9BC433EF; Fri, 5 May 2023 18:38:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1683311906; bh=u0otBwYFQ+z8N18f7DVMp5oxjO//N2A60QgEjFLrBOg=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=gPlOSuRGuKYxTGimCwFLk9f2RDwOmaaeCwKD4tbcFOJdiG3o5fyxtfFeuFzra8nJ9 NOL4KzIYcDdubbdjqTKKNGAZl1cSxCQZSYhY63UkHXOMc4Kbd4rBvlDn+WBB+zaCKC 7NzP6ja3qOzfy54q8WksTMrLNU5pMez5JPOiU6ngoruX5qeSxQj5Qk4nFzxAYhBlBw imxIDFCmO0svxoaqfTmCcA7ZiP6uqr61KnhKXhqvm/JVcSZhktJQI4AfVmKMJ+c0JH S5z0fd0Zsqya0OVar4fm2n5tv/5FmxEYamrrg717xG4IocBr+1Rf8oXUndl8/BpNal RXFmupFPNK6IA== Subject: [PATCH v2 1/5] shmem: Refactor shmem_symlink() From: Chuck Lever To: hughd@google.com, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Date: Fri, 05 May 2023 14:38:14 -0400 Message-ID: <168331188458.20728.11056177116501982469.stgit@oracle-102.nfsv4bat.org> In-Reply-To: <168331111400.20728.2327812215536431362.stgit@oracle-102.nfsv4bat.org> References: <168331111400.20728.2327812215536431362.stgit@oracle-102.nfsv4bat.org> User-Agent: StGit/1.5 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Chuck Lever De-duplicate the error handling paths. No change in behavior is expected. Suggested-by: Jeff Layton Signed-off-by: Chuck Lever --- mm/shmem.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index e40a08c5c6d7..721f9fd064aa 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -3161,26 +3161,22 @@ static int shmem_symlink(struct mnt_idmap *idmap, struct inode *dir, error = security_inode_init_security(inode, dir, &dentry->d_name, shmem_initxattrs, NULL); - if (error && error != -EOPNOTSUPP) { - iput(inode); - return error; - } + if (error && error != -EOPNOTSUPP) + goto out_iput; inode->i_size = len-1; if (len <= SHORT_SYMLINK_LEN) { inode->i_link = kmemdup(symname, len, GFP_KERNEL); if (!inode->i_link) { - iput(inode); - return -ENOMEM; + error = -ENOMEM; + goto out_iput; } inode->i_op = &shmem_short_symlink_operations; } else { inode_nohighmem(inode); error = shmem_get_folio(inode, 0, &folio, SGP_WRITE); - if (error) { - iput(inode); - return error; - } + if (error) + goto out_iput; inode->i_mapping->a_ops = &shmem_aops; inode->i_op = &shmem_symlink_inode_operations; memcpy(folio_address(folio), symname, len); @@ -3195,6 +3191,9 @@ static int shmem_symlink(struct mnt_idmap *idmap, struct inode *dir, d_instantiate(dentry, inode); dget(dentry); return 0; +out_iput: + iput(inode); + return error; } static void shmem_put_link(void *arg) From patchwork Fri May 5 18:38:41 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever X-Patchwork-Id: 13232956 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E4A37C77B7C for ; Fri, 5 May 2023 18:38:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232549AbjEESi7 (ORCPT ); Fri, 5 May 2023 14:38:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47462 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231730AbjEESi6 (ORCPT ); Fri, 5 May 2023 14:38:58 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B3DFA1AEC7 for ; Fri, 5 May 2023 11:38:53 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 39B23612BE for ; Fri, 5 May 2023 18:38:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 52D2CC433D2; Fri, 5 May 2023 18:38:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1683311932; bh=GdYSw9VqwgRlrzzZxLV54oL4HgWvYTGiC5taW2D05e4=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=S5ckk9kNu4j8HtDaVVdpiGd1KC24StnFNfUHVuiFfWD9VF772y37rx3nLD+oMGlJ9 j2dBjbFeYWt1PVlrjmshhNvwT74Y2oRVcdYurRfNqE43XwjnDrMhG4sQVSPusr+L8r dIEpBf3drtu24asv25kJtiu+xZVkggs1w/rzlh59cC59eNFTRvsIImz0CfgvlcPIti c6dySzJvl6L/p7jtXuE8lA5XhMXnqS+AAGo2TXglx1Jg5NTHeSZ0VeNMRD7FVayb8Y T0JLJmZxDf0gIfocYIMvu4deO2SEQcXi34r73yT0KWIqmuVXQiJ+xq3fBbT0Ihbm7V JlnDKpugrC2qg== Subject: [PATCH v2 2/5] shmem: Add dir_operations specific to tmpfs From: Chuck Lever To: hughd@google.com, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Date: Fri, 05 May 2023 14:38:41 -0400 Message-ID: <168331191128.20728.16486149742123519972.stgit@oracle-102.nfsv4bat.org> In-Reply-To: <168331111400.20728.2327812215536431362.stgit@oracle-102.nfsv4bat.org> References: <168331111400.20728.2327812215536431362.stgit@oracle-102.nfsv4bat.org> User-Agent: StGit/1.5 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Chuck Lever Copy the simple directory operations out of fs/libfs.c to create a set of dir_operations specific to tmpfs. These will be modified by a subsequent patch to replace the cursor-based directory entry offset mechanism. No behavior change is expected. Signed-off-by: Chuck Lever --- mm/shmem.c | 143 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 142 insertions(+), 1 deletion(-) diff --git a/mm/shmem.c b/mm/shmem.c index 721f9fd064aa..e48a0947bcaf 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -235,6 +235,7 @@ static const struct super_operations shmem_ops; const struct address_space_operations shmem_aops; static const struct file_operations shmem_file_operations; static const struct inode_operations shmem_inode_operations; +static const struct file_operations shmem_dir_operations; static const struct inode_operations shmem_dir_inode_operations; static const struct inode_operations shmem_special_inode_operations; static const struct vm_operations_struct shmem_vm_ops; @@ -2410,7 +2411,7 @@ static struct inode *shmem_get_inode(struct mnt_idmap *idmap, struct super_block /* Some things misbehave if size == 0 on a directory */ inode->i_size = 2 * BOGO_DIRENT_SIZE; inode->i_op = &shmem_dir_inode_operations; - inode->i_fop = &simple_dir_operations; + inode->i_fop = &shmem_dir_operations; break; case S_IFLNK: /* @@ -3235,6 +3236,137 @@ static const char *shmem_get_link(struct dentry *dentry, return folio_address(folio); } +static struct dentry *scan_positives(struct dentry *cursor, + struct list_head *p, + loff_t count, + struct dentry *last) +{ + struct dentry *dentry = cursor->d_parent, *found = NULL; + + spin_lock(&dentry->d_lock); + while ((p = p->next) != &dentry->d_subdirs) { + struct dentry *d = list_entry(p, struct dentry, d_child); + // we must at least skip cursors, to avoid livelocks + if (d->d_flags & DCACHE_DENTRY_CURSOR) + continue; + if (simple_positive(d) && !--count) { + spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED); + if (simple_positive(d)) + found = dget_dlock(d); + spin_unlock(&d->d_lock); + if (likely(found)) + break; + count = 1; + } + if (need_resched()) { + list_move(&cursor->d_child, p); + p = &cursor->d_child; + spin_unlock(&dentry->d_lock); + cond_resched(); + spin_lock(&dentry->d_lock); + } + } + spin_unlock(&dentry->d_lock); + dput(last); + return found; +} + +static loff_t shmem_dir_llseek(struct file *file, loff_t offset, int whence) +{ + struct dentry *dentry = file->f_path.dentry; + switch (whence) { + case 1: + offset += file->f_pos; + fallthrough; + case 0: + if (offset >= 0) + break; + fallthrough; + default: + return -EINVAL; + } + if (offset != file->f_pos) { + struct dentry *cursor = file->private_data; + struct dentry *to = NULL; + + inode_lock_shared(dentry->d_inode); + + if (offset > 2) + to = scan_positives(cursor, &dentry->d_subdirs, + offset - 2, NULL); + spin_lock(&dentry->d_lock); + if (to) + list_move(&cursor->d_child, &to->d_child); + else + list_del_init(&cursor->d_child); + spin_unlock(&dentry->d_lock); + dput(to); + + file->f_pos = offset; + + inode_unlock_shared(dentry->d_inode); + } + return offset; +} + +/** + * shmem_readdir - Emit entries starting at offset @ctx->pos + * @file: an open directory to iterate over + * @ctx: directory iteration context + * + * Caller must hold @file's i_rwsem to prevent insertion or removal of + * entries during this call. + * + * On entry, @ctx->pos contains an offset that represents the first entry + * to be read from the directory. + * + * The operation continues until there are no more entries to read, or + * until the ctx->actor indicates there is no more space in the caller's + * output buffer. + * + * On return, @ctx->pos contains an offset that will read the next entry + * in this directory when shmem_readdir() is called again with @ctx. + * + * Return values: + * %0 - Complete + */ +static int shmem_readdir(struct file *file, struct dir_context *ctx) +{ + struct dentry *dentry = file->f_path.dentry; + struct dentry *cursor = file->private_data; + struct list_head *anchor = &dentry->d_subdirs; + struct dentry *next = NULL; + struct list_head *p; + + if (!dir_emit_dots(file, ctx)) + return 0; + + if (ctx->pos == 2) + p = anchor; + else if (!list_empty(&cursor->d_child)) + p = &cursor->d_child; + else + return 0; + + while ((next = scan_positives(cursor, p, 1, next)) != NULL) { + if (!dir_emit(ctx, next->d_name.name, next->d_name.len, + d_inode(next)->i_ino, + fs_umode_to_dtype(d_inode(next)->i_mode))) + break; + ctx->pos++; + p = &next->d_child; + } + spin_lock(&dentry->d_lock); + if (next) + list_move_tail(&cursor->d_child, &next->d_child); + else + list_del_init(&cursor->d_child); + spin_unlock(&dentry->d_lock); + dput(next); + + return 0; +} + #ifdef CONFIG_TMPFS_XATTR static int shmem_fileattr_get(struct dentry *dentry, struct fileattr *fa) @@ -3987,6 +4119,15 @@ static const struct inode_operations shmem_inode_operations = { #endif }; +static const struct file_operations shmem_dir_operations = { +#ifdef CONFIG_TMPFS + .llseek = shmem_dir_llseek, + .iterate_shared = shmem_readdir, +#endif + .read = generic_read_dir, + .fsync = noop_fsync, +}; + static const struct inode_operations shmem_dir_inode_operations = { #ifdef CONFIG_TMPFS .getattr = shmem_getattr, From patchwork Fri May 5 18:39:07 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever X-Patchwork-Id: 13232961 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8562CC77B75 for ; Fri, 5 May 2023 18:39:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232218AbjEESjW (ORCPT ); Fri, 5 May 2023 14:39:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47592 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231580AbjEESjV (ORCPT ); Fri, 5 May 2023 14:39:21 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 327DC14E55 for ; Fri, 5 May 2023 11:39:20 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id BBE64612A1 for ; Fri, 5 May 2023 18:39:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D9A46C433D2; Fri, 5 May 2023 18:39:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1683311959; bh=jG5QsAgQy5Mjew+JAoL0OfLKEJrcHnLf8qAY4PJvrrE=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=p9GDQu+vZszpETOyvfR4rHyQa1kwd6uFM8dbwfuK7e/KOge9Me3RcbD0r5s9CEEgI 2V9AOmfXwJhcVU871H3wbRE8s76IAWFArmonrcfdKCFPM3FMrwnMHpMmMdwhzvDTaD VYuLBvTmIboasavp31nosHMD+Qnp8PS4gYDZdQlYc49geuoQFU8/0U8atgvy2Eh1+h oTJqsknyjv2wBvh/cxXhCeSsQ1WNnPPwIhEaaOtJLwWC978+uUGZoJY+chewonkuxM PRlBAnw+oyd9X7rp+Tu/Qkp5qLc0WlIuet91L2T9KJZsoP/wrhM1LLoD0EekA4RNDy 4/e+QwLTLgNPw== Subject: [PATCH v2 3/5] shmem: Add a per-directory xarray From: Chuck Lever To: hughd@google.com, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Date: Fri, 05 May 2023 14:39:07 -0400 Message-ID: <168331193783.20728.5584061722473821745.stgit@oracle-102.nfsv4bat.org> In-Reply-To: <168331111400.20728.2327812215536431362.stgit@oracle-102.nfsv4bat.org> References: <168331111400.20728.2327812215536431362.stgit@oracle-102.nfsv4bat.org> User-Agent: StGit/1.5 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Chuck Lever Add the infrastructure for managing a per-directory directory-offset-to-dentry map. For the moment it is unused. Signed-off-by: Chuck Lever --- include/linux/shmem_fs.h | 2 ++ mm/shmem.c | 28 ++++++++++++++++++++++++++++ 2 files changed, 30 insertions(+) diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h index 9029abd29b1c..c1a12eac778d 100644 --- a/include/linux/shmem_fs.h +++ b/include/linux/shmem_fs.h @@ -27,6 +27,8 @@ struct shmem_inode_info { atomic_t stop_eviction; /* hold when working on inode */ struct timespec64 i_crtime; /* file creation time */ unsigned int fsflags; /* flags for FS_IOC_[SG]ETFLAGS */ + struct xarray doff_map; /* dir offset to entry mapping */ + u32 next_doff; struct inode vfs_inode; }; diff --git a/mm/shmem.c b/mm/shmem.c index e48a0947bcaf..b78253996108 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -40,6 +40,8 @@ #include #include #include +#include + #include "swap.h" static struct vfsmount *shm_mnt; @@ -2412,6 +2414,8 @@ static struct inode *shmem_get_inode(struct mnt_idmap *idmap, struct super_block inode->i_size = 2 * BOGO_DIRENT_SIZE; inode->i_op = &shmem_dir_inode_operations; inode->i_fop = &shmem_dir_operations; + xa_init_flags(&info->doff_map, XA_FLAGS_ALLOC1); + info->next_doff = 0; break; case S_IFLNK: /* @@ -2930,6 +2934,22 @@ static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) return 0; } +static struct xarray *shmem_doff_map(struct inode *dir) +{ + return &SHMEM_I(dir)->doff_map; +} + +/* + * During fs teardown (eg. umount), a directory's doff_map might still + * contain entries. xa_destroy() cleans out anything that remains. + */ +static void shmem_doff_map_destroy(struct inode *inode) +{ + struct xarray *xa = shmem_doff_map(inode); + + xa_destroy(xa); +} + /* * File creation. Allocate an inode, and we're done.. */ @@ -3905,6 +3925,12 @@ static int shmem_show_options(struct seq_file *seq, struct dentry *root) return 0; } +#else /* CONFIG_TMPFS */ + +static inline void shmem_doff_map_destroy(struct inode *dir) +{ +} + #endif /* CONFIG_TMPFS */ static void shmem_put_super(struct super_block *sb) @@ -4052,6 +4078,8 @@ static void shmem_destroy_inode(struct inode *inode) { if (S_ISREG(inode->i_mode)) mpol_free_shared_policy(&SHMEM_I(inode)->policy); + if (S_ISDIR(inode->i_mode)) + shmem_doff_map_destroy(inode); } static void shmem_init_inode(void *foo) From patchwork Fri May 5 18:39:34 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever X-Patchwork-Id: 13232962 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D75CAC77B75 for ; Fri, 5 May 2023 18:39:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233105AbjEESjy (ORCPT ); Fri, 5 May 2023 14:39:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47826 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233294AbjEESju (ORCPT ); Fri, 5 May 2023 14:39:50 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D0CA91A4AE for ; Fri, 5 May 2023 11:39:46 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 656EE6123B for ; Fri, 5 May 2023 18:39:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 72C52C4339E; Fri, 5 May 2023 18:39:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1683311985; bh=mnpCJnLWNfPkHxmM+u+UF6L43j8pKp55GRe3BbzShFc=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=dt/3WmZqawbotPuR4zhXODVMzgAQJFtU6w6auHJr1A7S+XkIzFtfFk+q3ptGu8yR8 2iixaLu4XVTftOxrRSLTgQevQ3/bOiMNHtq7y/CWsi313PFGm2eC7sEbNmx60QtXrA yyx4yTPvgWCC71x28BXwfyT9VTO6l/mFyKEmjD5MsqLEY/9hM5+rOcYIloJO8H5cws WA1E+KHEHpO2/R6KGY37mcuIbJd1YAkDZxwk9btgWSOYM9lust1gHRgSfK8uc+nQ7J 5pTwMUvw2+WXyKy4VYxnu69W5Ydf4amfrsCvz7tzrC3j1fz+VFn0f6D57AvLXOxSdZ q2DdnRsZplhuQ== Subject: [PATCH v2 4/5] shmem: Add a shmem-specific dir_emit helper From: Chuck Lever To: hughd@google.com, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Date: Fri, 05 May 2023 14:39:34 -0400 Message-ID: <168331196437.20728.1655558228044135552.stgit@oracle-102.nfsv4bat.org> In-Reply-To: <168331111400.20728.2327812215536431362.stgit@oracle-102.nfsv4bat.org> References: <168331111400.20728.2327812215536431362.stgit@oracle-102.nfsv4bat.org> User-Agent: StGit/1.5 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Chuck Lever Clean up to improve the readability of shmem_readdir(). Signed-off-by: Chuck Lever --- mm/shmem.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index b78253996108..733b98ca8517 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -3329,6 +3329,15 @@ static loff_t shmem_dir_llseek(struct file *file, loff_t offset, int whence) return offset; } +static bool shmem_dir_emit(struct dir_context *ctx, struct dentry *dentry) +{ + struct inode *inode = d_inode(dentry); + + return ctx->actor(ctx, dentry->d_name.name, dentry->d_name.len, + ctx->pos, inode->i_ino, + fs_umode_to_dtype(inode->i_mode)); +} + /** * shmem_readdir - Emit entries starting at offset @ctx->pos * @file: an open directory to iterate over @@ -3369,9 +3378,7 @@ static int shmem_readdir(struct file *file, struct dir_context *ctx) return 0; while ((next = scan_positives(cursor, p, 1, next)) != NULL) { - if (!dir_emit(ctx, next->d_name.name, next->d_name.len, - d_inode(next)->i_ino, - fs_umode_to_dtype(d_inode(next)->i_mode))) + if (!shmem_dir_emit(ctx, dentry)) break; ctx->pos++; p = &next->d_child; From patchwork Fri May 5 18:39:53 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever X-Patchwork-Id: 13232963 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D4708C77B75 for ; Fri, 5 May 2023 18:40:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232769AbjEESkL (ORCPT ); Fri, 5 May 2023 14:40:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48510 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232343AbjEESkJ (ORCPT ); Fri, 5 May 2023 14:40:09 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3AEB01F4AE for ; Fri, 5 May 2023 11:40:06 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 8CE3B60BCB for ; Fri, 5 May 2023 18:40:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A70C3C433EF; Fri, 5 May 2023 18:40:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1683312005; bh=SxhrYvcxhBjeUt8wmGy6c2Qtho8JPzWD7lX0SBS7apY=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=mouuZBzrIkQ6xcAezlwBJgPALP+OH2G9vzy+PPWkCeIHjifkNX0zVIC8yHs3VjOqj JYE7jH6esduFWqv5z6AvKMpl5MHU9+Jjqw+Qi3+CJ9UtpifI5UxyZ3fRwP7p42uhZB VZlyIgC71LQUxDsw3B9TaVEv502XPp+PjmFQC4iCymkLJhP6ZdcMbSOSRlD8M1KHpO 63LUnlKzYEuyDVS5PZZR1CEP8XJoVpBFecy53JVtco0GAAPQV++9zuR7Mg1LfxHACF j3b1t/LCV+FxSZMJrl3t++4AoqTuYakM57b2bBdGV3FcbZzudb6ZnIWp7eNjia3lft BnFE+YPTSkKlQ== Subject: [PATCH v2 5/5] shmem: stable directory cookies From: Chuck Lever To: hughd@google.com, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Date: Fri, 05 May 2023 14:39:53 -0400 Message-ID: <168331199103.20728.3630197424738006199.stgit@oracle-102.nfsv4bat.org> In-Reply-To: <168331111400.20728.2327812215536431362.stgit@oracle-102.nfsv4bat.org> References: <168331111400.20728.2327812215536431362.stgit@oracle-102.nfsv4bat.org> User-Agent: StGit/1.5 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Chuck Lever The current cursor-based directory cookie mechanism doesn't work when a tmpfs filesystem is exported via NFS. This is because NFS clients do not open directories. Each server-side READDIR operation has to open the directory, read it, then close it. The cursor state for that directory, being associated strictly with the opened struct file, is discarded after each READDIR operation. Directory cookies are cached not only by NFS clients, but also by user space libraries on those clients. Essentially there is no way to invalidate those caches when directory offsets have changed on an NFS server after the offset-to-dentry mapping changes. Thus the whole application stack depends on unchanging directory cookies. The solution we've come up with is to make the directory cookie for each file in a tmpfs filesystem stable for the life of the directory entry it represents. Add a per-directory xarray. shmem_readdir() uses this to map each directory offset (an loff_t integer) to the memory address of a struct dentry. Signed-off-by: Chuck Lever --- mm/shmem.c | 202 +++++++++++++++++++++++++++++++----------------------------- 1 file changed, 106 insertions(+), 96 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index 733b98ca8517..35eb2f1368dd 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2939,6 +2939,55 @@ static struct xarray *shmem_doff_map(struct inode *dir) return &SHMEM_I(dir)->doff_map; } +static int shmem_doff_add(struct inode *dir, struct dentry *dentry) +{ + struct shmem_inode_info *info = SHMEM_I(dir); + struct xa_limit limit = XA_LIMIT(2, U32_MAX); + u32 offset; + int ret; + + if (dentry->d_fsdata) + return -EBUSY; + + offset = 0; + ret = xa_alloc_cyclic(shmem_doff_map(dir), &offset, dentry, limit, + &info->next_doff, GFP_KERNEL); + if (ret < 0) + return ret; + + dentry->d_fsdata = (void *)(unsigned long)offset; + return 0; +} + +static struct dentry *shmem_doff_find_after(struct dentry *dir, + unsigned long *offset) +{ + struct xarray *xa = shmem_doff_map(d_inode(dir)); + struct dentry *d, *found = NULL; + + spin_lock(&dir->d_lock); + d = xa_find_after(xa, offset, ULONG_MAX, XA_PRESENT); + if (d) { + spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED); + if (simple_positive(d)) + found = dget_dlock(d); + spin_unlock(&d->d_lock); + } + spin_unlock(&dir->d_lock); + return found; +} + +static void shmem_doff_remove(struct inode *dir, struct dentry *dentry) +{ + u32 offset = (u32)(unsigned long)dentry->d_fsdata; + + if (!offset) + return; + + xa_erase(shmem_doff_map(dir), offset); + dentry->d_fsdata = NULL; +} + /* * During fs teardown (eg. umount), a directory's doff_map might still * contain entries. xa_destroy() cleans out anything that remains. @@ -2971,6 +3020,10 @@ shmem_mknod(struct mnt_idmap *idmap, struct inode *dir, if (error && error != -EOPNOTSUPP) goto out_iput; + error = shmem_doff_add(dir, dentry); + if (error) + goto out_iput; + error = 0; dir->i_size += BOGO_DIRENT_SIZE; dir->i_ctime = dir->i_mtime = current_time(dir); @@ -3048,6 +3101,10 @@ static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentr goto out; } + ret = shmem_doff_add(dir, dentry); + if (ret) + goto out; + dir->i_size += BOGO_DIRENT_SIZE; inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode); inode_inc_iversion(dir); @@ -3066,6 +3123,8 @@ static int shmem_unlink(struct inode *dir, struct dentry *dentry) if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) shmem_free_inode(inode->i_sb); + shmem_doff_remove(dir, dentry); + dir->i_size -= BOGO_DIRENT_SIZE; inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode); inode_inc_iversion(dir); @@ -3124,24 +3183,37 @@ static int shmem_rename2(struct mnt_idmap *idmap, { struct inode *inode = d_inode(old_dentry); int they_are_dirs = S_ISDIR(inode->i_mode); + int error; if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) return -EINVAL; - if (flags & RENAME_EXCHANGE) + if (flags & RENAME_EXCHANGE) { + shmem_doff_remove(old_dir, old_dentry); + shmem_doff_remove(new_dir, new_dentry); + error = shmem_doff_add(new_dir, old_dentry); + if (error) + return error; + error = shmem_doff_add(old_dir, new_dentry); + if (error) + return error; return simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry); + } if (!simple_empty(new_dentry)) return -ENOTEMPTY; if (flags & RENAME_WHITEOUT) { - int error; - error = shmem_whiteout(idmap, old_dir, old_dentry); if (error) return error; } + shmem_doff_remove(old_dir, old_dentry); + error = shmem_doff_add(new_dir, old_dentry); + if (error) + return error; + if (d_really_is_positive(new_dentry)) { (void) shmem_unlink(new_dir, new_dentry); if (they_are_dirs) { @@ -3206,6 +3278,11 @@ static int shmem_symlink(struct mnt_idmap *idmap, struct inode *dir, folio_unlock(folio); folio_put(folio); } + + error = shmem_doff_add(dir, dentry); + if (error) + goto out_iput; + dir->i_size += BOGO_DIRENT_SIZE; dir->i_ctime = dir->i_mtime = current_time(dir); inode_inc_iversion(dir); @@ -3256,77 +3333,20 @@ static const char *shmem_get_link(struct dentry *dentry, return folio_address(folio); } -static struct dentry *scan_positives(struct dentry *cursor, - struct list_head *p, - loff_t count, - struct dentry *last) -{ - struct dentry *dentry = cursor->d_parent, *found = NULL; - - spin_lock(&dentry->d_lock); - while ((p = p->next) != &dentry->d_subdirs) { - struct dentry *d = list_entry(p, struct dentry, d_child); - // we must at least skip cursors, to avoid livelocks - if (d->d_flags & DCACHE_DENTRY_CURSOR) - continue; - if (simple_positive(d) && !--count) { - spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED); - if (simple_positive(d)) - found = dget_dlock(d); - spin_unlock(&d->d_lock); - if (likely(found)) - break; - count = 1; - } - if (need_resched()) { - list_move(&cursor->d_child, p); - p = &cursor->d_child; - spin_unlock(&dentry->d_lock); - cond_resched(); - spin_lock(&dentry->d_lock); - } - } - spin_unlock(&dentry->d_lock); - dput(last); - return found; -} - static loff_t shmem_dir_llseek(struct file *file, loff_t offset, int whence) { - struct dentry *dentry = file->f_path.dentry; switch (whence) { - case 1: - offset += file->f_pos; - fallthrough; - case 0: - if (offset >= 0) - break; - fallthrough; - default: - return -EINVAL; - } - if (offset != file->f_pos) { - struct dentry *cursor = file->private_data; - struct dentry *to = NULL; - - inode_lock_shared(dentry->d_inode); - - if (offset > 2) - to = scan_positives(cursor, &dentry->d_subdirs, - offset - 2, NULL); - spin_lock(&dentry->d_lock); - if (to) - list_move(&cursor->d_child, &to->d_child); - else - list_del_init(&cursor->d_child); - spin_unlock(&dentry->d_lock); - dput(to); - - file->f_pos = offset; - - inode_unlock_shared(dentry->d_inode); + case SEEK_CUR: + offset += file->f_pos; + fallthrough; + case SEEK_SET: + if (offset >= 0) + break; + fallthrough; + default: + return -EINVAL; } - return offset; + return vfs_setpos(file, offset, U32_MAX); } static bool shmem_dir_emit(struct dir_context *ctx, struct dentry *dentry) @@ -3334,7 +3354,7 @@ static bool shmem_dir_emit(struct dir_context *ctx, struct dentry *dentry) struct inode *inode = d_inode(dentry); return ctx->actor(ctx, dentry->d_name.name, dentry->d_name.len, - ctx->pos, inode->i_ino, + (loff_t)dentry->d_fsdata, inode->i_ino, fs_umode_to_dtype(inode->i_mode)); } @@ -3361,36 +3381,26 @@ static bool shmem_dir_emit(struct dir_context *ctx, struct dentry *dentry) */ static int shmem_readdir(struct file *file, struct dir_context *ctx) { - struct dentry *dentry = file->f_path.dentry; - struct dentry *cursor = file->private_data; - struct list_head *anchor = &dentry->d_subdirs; - struct dentry *next = NULL; - struct list_head *p; - - if (!dir_emit_dots(file, ctx)) - return 0; + struct dentry *dentry, *dir = file->f_path.dentry; + unsigned long offset; - if (ctx->pos == 2) - p = anchor; - else if (!list_empty(&cursor->d_child)) - p = &cursor->d_child; - else - return 0; + lockdep_assert_held(&d_inode(dir)->i_rwsem); - while ((next = scan_positives(cursor, p, 1, next)) != NULL) { - if (!shmem_dir_emit(ctx, dentry)) + if (!dir_emit_dots(file, ctx)) + goto out; + for (offset = ctx->pos - 1; offset < ULONG_MAX - 1;) { + dentry = shmem_doff_find_after(dir, &offset); + if (!dentry) break; - ctx->pos++; - p = &next->d_child; + if (!shmem_dir_emit(ctx, dentry)) { + dput(dentry); + break; + } + ctx->pos = offset + 1; + dput(dentry); } - spin_lock(&dentry->d_lock); - if (next) - list_move_tail(&cursor->d_child, &next->d_child); - else - list_del_init(&cursor->d_child); - spin_unlock(&dentry->d_lock); - dput(next); +out: return 0; }