From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4CEAB2EC081 for ; Thu, 23 Apr 2026 22:22:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776982970; cv=none; b=stJ/nRtCglUe1A1wqLHGG25iBwZdPGtBtNIV7UWI6ALBajbcN4xnqVNzukbeAEtZJ/CERnH4OQXP2zAWOd0n/XB1jQLhm8Ts29Tb94qc1lnUmZDhvsn9CiXjg0WdRRRRboCti/okc/QDoB43ZO8kKdu+aF7IlYuccGxEGNFnaD8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776982970; c=relaxed/simple; bh=j+CNTHw4JaXJ04qPB20Oy/gfNlGU9rt5C2hsX5WusIU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=WPVlRzBxJk/eOE3rtfwd06YVpdr9L2eVvUe2i4nkVr+wnY9Tq2522bPlz0itPvbDNONkDi49My5/XtgAY4OkxH4klCiYnNUof1agjbz3mpRrLMsGRoyYIHTAvAgRGrSuzjAh2F7HTpc0QVSzraEzMjXHTdiEmnL6IL59cM5RJ9g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=DxXphZ6x; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="DxXphZ6x" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1776982967; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=TahHXd/0zLYPsZIgom/gtrfZo11GRDjkH9gAacnDx7E=; b=DxXphZ6x/WgSMDPbSvH7aghrOZZJBovjCC8ulmZrTiP3g/OsjurX9ct8KvecAR4IwSzjoj OiutNtiUmoeLEclt7f4ksgmvkRX7dLYzob47UovFjznxc4nv6ojeWWvg4xyoCwk+BTJ3Gz DCfjL9HBJxbanCA4XrNXGjSDMCgl9Hk= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-657-2zaffEGoMVyjOZLej1VECw-1; Thu, 23 Apr 2026 18:22:41 -0400 X-MC-Unique: 2zaffEGoMVyjOZLej1VECw-1 X-Mimecast-MFC-AGG-ID: 2zaffEGoMVyjOZLej1VECw_1776982960 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 525771956056; Thu, 23 Apr 2026 22:22:40 +0000 (UTC) Received: from warthog.procyon.org.com (unknown [10.44.48.17]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 427C719560AB; Thu, 23 Apr 2026 22:22:37 +0000 (UTC) From: David Howells To: Christian Brauner Cc: David Howells , Paulo Alcantara , netfs@lists.linux.dev, linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Marc Dionne Subject: [PATCH 4/4] afs: Fix RCU handling of symlinks in RCU pathwalk Date: Thu, 23 Apr 2026 23:22:07 +0100 Message-ID: <20260423222209.3054909-5-dhowells@redhat.com> In-Reply-To: <20260423222209.3054909-1-dhowells@redhat.com> References: <20260423222209.3054909-1-dhowells@redhat.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 The afs filesystem in the kernel doesn't handle RCU pathwalk of symlinks correctly. The problem is twofold: firstly, it doesn't treat the buffer pointers as RCU pointers with the appropriate barriering; and secondly, it can race with another thread updating the contents of the symlink because a third party updated it on the server. Fix this by the following means: (1) Keep a separate copy of the symlink contents with an rcu_head. This is always going to be a lot smaller than a page, so it can be kmalloc'd and save quite a bit of memory. It also needs a refcount for non-RCU pathwalk. (2) Split the symlink read and write-to-cache routines in afs from those for directories. (3) Discard the I/O buffer as soon as the write-to-cache completes as this is a full page (plus a folio_queue). (4) If there's no cache, discard the I/O buffer immediately after reading and copying if there is no cache. Fixes: 6698c02d64b2 ("afs: Locally initialise the contents of a new symlink on creation") Closes: https://sashiko.dev/#/patchset/20260326104544.509518-1-dhowells%40redhat.com Signed-off-by: David Howells cc: Marc Dionne cc: linux-afs@lists.infradead.org cc: linux-fsdevel@vger.kernel.org --- fs/afs/Makefile | 1 + fs/afs/dir.c | 33 +++++-- fs/afs/fsclient.c | 4 +- fs/afs/inode.c | 105 +------------------- fs/afs/internal.h | 35 +++++-- fs/afs/symlink.c | 242 +++++++++++++++++++++++++++++++++++++++++++++ fs/afs/yfsclient.c | 4 +- 7 files changed, 303 insertions(+), 121 deletions(-) create mode 100644 fs/afs/symlink.c diff --git a/fs/afs/Makefile b/fs/afs/Makefile index b49b8fe682f3..0d8f1982d596 100644 --- a/fs/afs/Makefile +++ b/fs/afs/Makefile @@ -30,6 +30,7 @@ kafs-y := \ server.o \ server_list.o \ super.o \ + symlink.o \ validation.o \ vlclient.o \ vl_alias.o \ diff --git a/fs/afs/dir.c b/fs/afs/dir.c index aaaa55878ffd..40f6791114ec 100644 --- a/fs/afs/dir.c +++ b/fs/afs/dir.c @@ -68,7 +68,7 @@ const struct inode_operations afs_dir_inode_operations = { }; const struct address_space_operations afs_dir_aops = { - .writepages = afs_single_writepages, + .writepages = afs_dir_writepages, }; const struct dentry_operations afs_fs_dentry_operations = { @@ -294,7 +294,7 @@ static ssize_t afs_do_read_single(struct afs_vnode *dvnode, struct file *file) return ret; } -ssize_t afs_read_single(struct afs_vnode *dvnode, struct file *file) +static ssize_t afs_read_single(struct afs_vnode *dvnode, struct file *file) { ssize_t ret; @@ -1763,13 +1763,20 @@ static int afs_link(struct dentry *from, struct inode *dir, return ret; } +static void afs_symlink_put(struct afs_operation *op) +{ + kfree(op->create.symlink); + op->create.symlink = NULL; + afs_create_put(op); +} + static const struct afs_operation_ops afs_symlink_operation = { .issue_afs_rpc = afs_fs_symlink, .issue_yfs_rpc = yfs_fs_symlink, .success = afs_create_success, .aborted = afs_check_for_remote_deletion, .edit_dir = afs_create_edit_dir, - .put = afs_create_put, + .put = afs_symlink_put, }; /* @@ -1779,7 +1786,9 @@ static int afs_symlink(struct mnt_idmap *idmap, struct inode *dir, struct dentry *dentry, const char *content) { struct afs_operation *op; + struct afs_symlink *symlink; struct afs_vnode *dvnode = AFS_FS_I(dir); + size_t clen = strlen(content); int ret; _enter("{%llx:%llu},{%pd},%s", @@ -1791,12 +1800,20 @@ static int afs_symlink(struct mnt_idmap *idmap, struct inode *dir, goto error; ret = -EINVAL; - if (strlen(content) >= AFSPATHMAX) + if (clen >= AFSPATHMAX) + goto error; + + ret = -ENOMEM; + symlink = kmalloc_flex(struct afs_symlink, content, clen + 1, GFP_KERNEL); + if (!symlink) goto error; + refcount_set(&symlink->ref, 1); + memcpy(symlink->content, content, clen + 1); op = afs_alloc_operation(NULL, dvnode->volume); if (IS_ERR(op)) { ret = PTR_ERR(op); + kfree(symlink); goto error; } @@ -1808,7 +1825,7 @@ static int afs_symlink(struct mnt_idmap *idmap, struct inode *dir, op->dentry = dentry; op->ops = &afs_symlink_operation; op->create.reason = afs_edit_dir_for_symlink; - op->create.symlink = content; + op->create.symlink = symlink; op->mtime = current_time(dir); ret = afs_do_sync_operation(op); afs_dir_unuse_cookie(dvnode, ret); @@ -2192,10 +2209,10 @@ static int afs_rename(struct mnt_idmap *idmap, struct inode *old_dir, } /* - * Write the file contents to the cache as a single blob. + * Write the directory contents to the cache as a single blob. */ -int afs_single_writepages(struct address_space *mapping, - struct writeback_control *wbc) +int afs_dir_writepages(struct address_space *mapping, + struct writeback_control *wbc) { struct afs_vnode *dvnode = AFS_FS_I(mapping->host); struct iov_iter iter; diff --git a/fs/afs/fsclient.c b/fs/afs/fsclient.c index 95494d5f2b8a..a2ffd60889f8 100644 --- a/fs/afs/fsclient.c +++ b/fs/afs/fsclient.c @@ -886,7 +886,7 @@ void afs_fs_symlink(struct afs_operation *op) namesz = name->len; padsz = (4 - (namesz & 3)) & 3; - c_namesz = strlen(op->create.symlink); + c_namesz = strlen(op->create.symlink->content); c_padsz = (4 - (c_namesz & 3)) & 3; reqsz = (6 * 4) + namesz + padsz + c_namesz + c_padsz + (6 * 4); @@ -910,7 +910,7 @@ void afs_fs_symlink(struct afs_operation *op) bp = (void *) bp + padsz; } *bp++ = htonl(c_namesz); - memcpy(bp, op->create.symlink, c_namesz); + memcpy(bp, op->create.symlink->content, c_namesz); bp = (void *) bp + c_namesz; if (c_padsz > 0) { memset(bp, 0, c_padsz); diff --git a/fs/afs/inode.c b/fs/afs/inode.c index 5207c4a003f6..ff2b8fc7f3df 100644 --- a/fs/afs/inode.c +++ b/fs/afs/inode.c @@ -25,105 +25,6 @@ #include "internal.h" #include "afs_fs.h" -void afs_init_new_symlink(struct afs_vnode *vnode, struct afs_operation *op) -{ - size_t size = strlen(op->create.symlink) + 1; - size_t dsize = 0; - char *p; - - if (netfs_alloc_folioq_buffer(NULL, &vnode->directory, &dsize, size, - mapping_gfp_mask(vnode->netfs.inode.i_mapping)) < 0) - return; - - vnode->directory_size = dsize; - p = kmap_local_folio(folioq_folio(vnode->directory, 0), 0); - memcpy(p, op->create.symlink, size); - kunmap_local(p); - set_bit(AFS_VNODE_DIR_READ, &vnode->flags); - netfs_single_mark_inode_dirty(&vnode->netfs.inode); -} - -static void afs_put_link(void *arg) -{ - struct folio *folio = virt_to_folio(arg); - - kunmap_local(arg); - folio_put(folio); -} - -const char *afs_get_link(struct dentry *dentry, struct inode *inode, - struct delayed_call *callback) -{ - struct afs_vnode *vnode = AFS_FS_I(inode); - struct folio *folio; - char *content; - ssize_t ret; - - if (!dentry) { - /* RCU pathwalk. */ - if (!test_bit(AFS_VNODE_DIR_READ, &vnode->flags) || !afs_check_validity(vnode)) - return ERR_PTR(-ECHILD); - goto good; - } - - if (test_bit(AFS_VNODE_DIR_READ, &vnode->flags)) - goto fetch; - - ret = afs_validate(vnode, NULL); - if (ret < 0) - return ERR_PTR(ret); - - if (!test_and_clear_bit(AFS_VNODE_ZAP_DATA, &vnode->flags) && - test_bit(AFS_VNODE_DIR_READ, &vnode->flags)) - goto good; - -fetch: - if (down_write_killable(&vnode->validate_lock) < 0) - return ERR_PTR(-ERESTARTSYS); - if (test_and_clear_bit(AFS_VNODE_ZAP_DATA, &vnode->flags) || - !test_bit(AFS_VNODE_DIR_READ, &vnode->flags)) { - ret = afs_read_single(vnode, NULL); - if (ret < 0) { - up_write(&vnode->validate_lock); - return ERR_PTR(ret); - } - set_bit(AFS_VNODE_DIR_READ, &vnode->flags); - } - - up_write(&vnode->validate_lock); - -good: - folio = folioq_folio(vnode->directory, 0); - folio_get(folio); - content = kmap_local_folio(folio, 0); - set_delayed_call(callback, afs_put_link, content); - return content; -} - -int afs_readlink(struct dentry *dentry, char __user *buffer, int buflen) -{ - DEFINE_DELAYED_CALL(done); - const char *content; - int len; - - content = afs_get_link(dentry, d_inode(dentry), &done); - if (IS_ERR(content)) { - do_delayed_call(&done); - return PTR_ERR(content); - } - - len = umin(strlen(content), buflen); - if (copy_to_user(buffer, content, len)) - len = -EFAULT; - do_delayed_call(&done); - return len; -} - -static const struct inode_operations afs_symlink_inode_operations = { - .get_link = afs_get_link, - .readlink = afs_readlink, -}; - static noinline void dump_vnode(struct afs_vnode *vnode, struct afs_vnode *parent_vnode) { static unsigned long once_only; @@ -223,7 +124,7 @@ static int afs_inode_init_from_status(struct afs_operation *op, inode->i_mode = S_IFLNK | status->mode; inode->i_op = &afs_symlink_inode_operations; } - inode->i_mapping->a_ops = &afs_dir_aops; + inode->i_mapping->a_ops = &afs_symlink_aops; inode_nohighmem(inode); mapping_set_release_always(inode->i_mapping); break; @@ -765,12 +666,14 @@ void afs_evict_inode(struct inode *inode) .range_end = LLONG_MAX, }; - afs_single_writepages(inode->i_mapping, &wbc); + inode->i_mapping->a_ops->writepages(inode->i_mapping, &wbc); } netfs_wait_for_outstanding_io(inode); truncate_inode_pages_final(&inode->i_data); netfs_free_folioq_buffer(vnode->directory); + if (vnode->symlink) + afs_replace_symlink(vnode, NULL); afs_set_cache_aux(vnode, &aux); netfs_clear_inode_writeback(inode, &aux); diff --git a/fs/afs/internal.h b/fs/afs/internal.h index 009064b8d661..802ae22133ae 100644 --- a/fs/afs/internal.h +++ b/fs/afs/internal.h @@ -711,6 +711,7 @@ struct afs_vnode { #define AFS_VNODE_DIR_READ 11 /* Set if we've read a dir's contents */ struct folio_queue *directory; /* Directory contents */ + struct afs_symlink __rcu *symlink; /* Symlink content */ struct list_head wb_keys; /* List of keys available for writeback */ struct list_head pending_locks; /* locks waiting to be granted */ struct list_head granted_locks; /* locks granted on this file */ @@ -777,6 +778,15 @@ struct afs_permits { struct afs_permit permits[] __counted_by(nr_permits); /* List of permits sorted by key pointer */ }; +/* + * Copy of symlink content for normal use. + */ +struct afs_symlink { + struct rcu_head rcu; + refcount_t ref; + char content[]; +}; + /* * Error prioritisation and accumulation. */ @@ -888,7 +898,7 @@ struct afs_operation { struct { int reason; /* enum afs_edit_dir_reason */ mode_t mode; - const char *symlink; + struct afs_symlink *symlink; } create; struct { bool need_rehash; @@ -1099,13 +1109,12 @@ extern const struct inode_operations afs_dir_inode_operations; extern const struct address_space_operations afs_dir_aops; extern const struct dentry_operations afs_fs_dentry_operations; -ssize_t afs_read_single(struct afs_vnode *dvnode, struct file *file); ssize_t afs_read_dir(struct afs_vnode *dvnode, struct file *file) __acquires(&dvnode->validate_lock); extern void afs_d_release(struct dentry *); extern void afs_check_for_remote_deletion(struct afs_operation *); -int afs_single_writepages(struct address_space *mapping, - struct writeback_control *wbc); +int afs_dir_writepages(struct address_space *mapping, + struct writeback_control *wbc); /* * dir_edit.c @@ -1247,10 +1256,6 @@ extern void afs_fs_probe_cleanup(struct afs_net *); */ extern const struct afs_operation_ops afs_fetch_status_operation; -void afs_init_new_symlink(struct afs_vnode *vnode, struct afs_operation *op); -const char *afs_get_link(struct dentry *dentry, struct inode *inode, - struct delayed_call *callback); -int afs_readlink(struct dentry *dentry, char __user *buffer, int buflen); extern void afs_vnode_commit_status(struct afs_operation *, struct afs_vnode_param *); extern int afs_fetch_status(struct afs_vnode *, struct key *, bool, afs_access_t *); extern int afs_ilookup5_test_by_fid(struct inode *, void *); @@ -1600,6 +1605,20 @@ void afs_detach_volume_from_servers(struct afs_volume *volume, struct afs_server extern int __init afs_fs_init(void); extern void afs_fs_exit(void); +/* + * symlink.c + */ +extern const struct inode_operations afs_symlink_inode_operations; +extern const struct address_space_operations afs_symlink_aops; + +void afs_replace_symlink(struct afs_vnode *vnode, struct afs_symlink *symlink); +void afs_init_new_symlink(struct afs_vnode *vnode, struct afs_operation *op); +const char *afs_get_link(struct dentry *dentry, struct inode *inode, + struct delayed_call *callback); +int afs_readlink(struct dentry *dentry, char __user *buffer, int buflen); +int afs_symlink_writepages(struct address_space *mapping, + struct writeback_control *wbc); + /* * validation.c */ diff --git a/fs/afs/symlink.c b/fs/afs/symlink.c new file mode 100644 index 000000000000..8d2521c5f19d --- /dev/null +++ b/fs/afs/symlink.c @@ -0,0 +1,242 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* AFS filesystem symbolic link handling + * + * Copyright (C) 2026 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include +#include +#include +#include +#include +#include "internal.h" + +static void afs_put_symlink(struct afs_symlink *symlink) +{ + if (refcount_dec_and_test(&symlink->ref)) + kfree_rcu(symlink, rcu); +} + +void afs_replace_symlink(struct afs_vnode *vnode, struct afs_symlink *symlink) +{ + struct afs_symlink *old; + + old = rcu_replace_pointer(vnode->symlink, symlink, + lockdep_is_held(&vnode->validate_lock)); + if (old) + afs_put_symlink(old); +} + +/* + * Set up a locally created symlink inode for immediate write to the cache. + */ +void afs_init_new_symlink(struct afs_vnode *vnode, struct afs_operation *op) +{ + size_t dsize = 0; + size_t size = strlen(op->create.symlink->content) + 1; + char *p; + + rcu_assign_pointer(vnode->symlink, op->create.symlink); + op->create.symlink = NULL; + + if (!fscache_cookie_enabled(netfs_i_cookie(&vnode->netfs))) + return; + + if (netfs_alloc_folioq_buffer(NULL, &vnode->directory, &dsize, size, + mapping_gfp_mask(vnode->netfs.inode.i_mapping)) < 0) + return; + + vnode->directory_size = dsize; + p = kmap_local_folio(folioq_folio(vnode->directory, 0), 0); + memcpy(p, vnode->symlink, size); + kunmap_local(p); + netfs_single_mark_inode_dirty(&vnode->netfs.inode); +} + +/* + * Read a symlink in a single download. + */ +static ssize_t afs_do_read_symlink(struct afs_vnode *vnode) +{ + struct afs_symlink *symlink; + struct iov_iter iter; + ssize_t ret; + loff_t i_size; + + i_size = i_size_read(&vnode->netfs.inode); + if (i_size > PAGE_SIZE - 1) { + trace_afs_file_error(vnode, -EFBIG, afs_file_error_dir_big); + return -EFBIG; + } + + if (!vnode->directory) { + size_t cur_size = 0; + + ret = netfs_alloc_folioq_buffer(NULL, + &vnode->directory, &cur_size, PAGE_SIZE, + mapping_gfp_mask(vnode->netfs.inode.i_mapping)); + vnode->directory_size = PAGE_SIZE - 1; + if (ret < 0) + return ret; + } + + iov_iter_folio_queue(&iter, ITER_DEST, vnode->directory, 0, 0, PAGE_SIZE); + + /* AFS requires us to perform the read of a symlink as a single unit to + * avoid issues with the content being changed between reads. + */ + ret = netfs_read_single(&vnode->netfs.inode, NULL, &iter); + if (ret >= 0) { + i_size = i_size_read(&vnode->netfs.inode); + if (i_size > PAGE_SIZE - 1) { + trace_afs_file_error(vnode, -EFBIG, afs_file_error_dir_big); + return -EFBIG; + } + vnode->directory_size = i_size; + + /* Copy the symlink. */ + symlink = kmalloc_flex(struct afs_symlink, content, i_size + 1, + GFP_KERNEL); + if (!symlink) + return -ENOMEM; + + refcount_set(&symlink->ref, 1); + symlink->content[i_size] = 0; + + const char *s = kmap_local_folio(folioq_folio(vnode->directory, 0), 0); + + memcpy(symlink->content, s, i_size); + kunmap_local(s); + + afs_replace_symlink(vnode, symlink); + } + + if (!fscache_cookie_enabled(netfs_i_cookie(&vnode->netfs))) { + netfs_free_folioq_buffer(vnode->directory); + vnode->directory = NULL; + vnode->directory_size = 0; + } + + return ret; +} + +static ssize_t afs_read_symlink(struct afs_vnode *vnode) +{ + ssize_t ret; + + fscache_use_cookie(afs_vnode_cache(vnode), false); + ret = afs_do_read_symlink(vnode); + fscache_unuse_cookie(afs_vnode_cache(vnode), NULL, NULL); + return ret; +} + +static void afs_put_link(void *arg) +{ + afs_put_symlink(arg); +} + +const char *afs_get_link(struct dentry *dentry, struct inode *inode, + struct delayed_call *callback) +{ + struct afs_symlink *symlink; + struct afs_vnode *vnode = AFS_FS_I(inode); + ssize_t ret; + + if (!dentry) { + /* RCU pathwalk. */ + if (!vnode->symlink || !afs_check_validity(vnode)) + return ERR_PTR(-ECHILD); + set_delayed_call(callback, NULL, NULL); + return rcu_dereference(vnode->symlink)->content; + } + + if (vnode->symlink) { + ret = afs_validate(vnode, NULL); + if (ret < 0) + return ERR_PTR(ret); + + down_read(&vnode->validate_lock); + if (!test_bit(AFS_VNODE_ZAP_DATA, &vnode->flags)) + goto good; + up_read(&vnode->validate_lock); + } + + if (down_write_killable(&vnode->validate_lock) < 0) + return ERR_PTR(-ERESTARTSYS); + if (!vnode->symlink || + test_and_clear_bit(AFS_VNODE_ZAP_DATA, &vnode->flags)) { + ret = afs_read_symlink(vnode); + if (ret < 0) { + up_write(&vnode->validate_lock); + return ERR_PTR(ret); + } + } + + downgrade_write(&vnode->validate_lock); + +good: + symlink = rcu_dereference_protected(vnode->symlink, + lockdep_is_held(&vnode->validate_lock)); + refcount_inc(&symlink->ref); + up_read(&vnode->validate_lock); + + set_delayed_call(callback, afs_put_link, symlink); + return symlink->content; +} + +int afs_readlink(struct dentry *dentry, char __user *buffer, int buflen) +{ + DEFINE_DELAYED_CALL(done); + const char *content; + int len; + + content = afs_get_link(dentry, d_inode(dentry), &done); + if (IS_ERR(content)) { + do_delayed_call(&done); + return PTR_ERR(content); + } + + len = umin(strlen(content), buflen); + if (copy_to_user(buffer, content, len)) + len = -EFAULT; + do_delayed_call(&done); + return len; +} + +/* + * Write the symlink contents to the cache as a single blob. We then throw + * away the page we used to receive it. + */ +int afs_symlink_writepages(struct address_space *mapping, + struct writeback_control *wbc) +{ + struct afs_vnode *vnode = AFS_FS_I(mapping->host); + struct iov_iter iter; + int ret = 0; + + down_write(&vnode->validate_lock); + + if (vnode->directory && + atomic64_read(&vnode->cb_expires_at) != AFS_NO_CB_PROMISE) { + iov_iter_folio_queue(&iter, ITER_SOURCE, vnode->directory, 0, 0, + i_size_read(&vnode->netfs.inode)); + ret = netfs_writeback_single(mapping, wbc, &iter); + } + + netfs_free_folioq_buffer(vnode->directory); + vnode->directory = NULL; + vnode->directory_size = 0; + + up_write(&vnode->validate_lock); + return ret; +} + +const struct inode_operations afs_symlink_inode_operations = { + .get_link = afs_get_link, + .readlink = afs_readlink, +}; + +const struct address_space_operations afs_symlink_aops = { + .writepages = afs_symlink_writepages, +}; diff --git a/fs/afs/yfsclient.c b/fs/afs/yfsclient.c index 24fb562ebd33..d941179730a9 100644 --- a/fs/afs/yfsclient.c +++ b/fs/afs/yfsclient.c @@ -960,7 +960,7 @@ void yfs_fs_symlink(struct afs_operation *op) _enter(""); - contents_sz = strlen(op->create.symlink); + contents_sz = strlen(op->create.symlink->content); call = afs_alloc_flat_call(op->net, &yfs_RXYFSSymlink, sizeof(__be32) + sizeof(struct yfs_xdr_RPCFlags) + @@ -981,7 +981,7 @@ void yfs_fs_symlink(struct afs_operation *op) bp = xdr_encode_u32(bp, 0); /* RPC flags */ bp = xdr_encode_YFSFid(bp, &dvp->fid); bp = xdr_encode_name(bp, name); - bp = xdr_encode_string(bp, op->create.symlink, contents_sz); + bp = xdr_encode_string(bp, op->create.symlink->content, contents_sz); bp = xdr_encode_YFSStoreStatus(bp, &mode, &op->mtime); yfs_check_req(call, bp);