[45/64] cachefiles: Implement metadata/coherency data storage in xattrs

Message ID	163819641320.215744.16346770087799536862.stgit@warthog.procyon.org.uk (mailing list archive)
State	New, archived
Headers	show Return-Path: <ceph-devel-owner@kernel.org> Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH 45/64] cachefiles: Implement metadata/coherency data storage in xattrs From: David Howells <dhowells@redhat.com> To: linux-cachefs@redhat.com Cc: dhowells@redhat.com, Trond Myklebust <trondmy@hammerspace.com>, Anna Schumaker <anna.schumaker@netapp.com>, Steve French <sfrench@samba.org>, Dominique Martinet <asmadeus@codewreck.org>, Jeff Layton <jlayton@kernel.org>, Matthew Wilcox <willy@infradead.org>, Alexander Viro <viro@zeniv.linux.org.uk>, Omar Sandoval <osandov@osandov.com>, Linus Torvalds <torvalds@linux-foundation.org>, linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Date: Mon, 29 Nov 2021 14:33:33 +0000 Message-ID: <163819641320.215744.16346770087799536862.stgit@warthog.procyon.org.uk> In-Reply-To: <163819575444.215744.318477214576928110.stgit@warthog.procyon.org.uk> References: <163819575444.215744.318477214576928110.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.23 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk
Series	fscache, cachefiles: Rewrite \| expand [00/64] fscache, cachefiles: Rewrite [01/64] fscache, cachefiles: Disable configuration [04/64] netfs: Display the netfs inode number in the netfs_read tracepoint [05/64] netfs: Pass a flag to ->prepare_write() to say if there's no alloc'd space [06/64] fscache: Introduce new driver [07/64] fscache: Implement a hash function [08/64] fscache: Implement cache registration [09/64] fscache: Implement volume registration [10/64] fscache: Implement cookie registration [11/64] fscache: Implement cache-level access helpers [12/64] fscache: Implement volume-level access helpers [13/64] fscache: Implement cookie-level access helpers [14/64] fscache: Implement functions add/remove a cache [15/64] fscache: Provide and use cache methods to lookup/create/free a volume [16/64] fscache: Add a function for a cache backend to note an I/O error [17/64] fscache: Implement simple cookie state machine [18/64] fscache: Implement cookie user counting and resource pinning [19/64] fscache: Implement cookie invalidation [20/64] fscache: Provide a means to begin an operation [21/64] fscache: Count data storage objects in a cache [22/64] fscache: Provide read/write stat counters for the cache [23/64] fscache: Provide a function to let the netfs update its coherency data [24/64] netfs: Pass more information on how to deal with a hole in the cache [25/64] fscache: Implement raw I/O interface [26/64] fscache: Implement higher-level write I/O interface [27/64] vfs, fscache: Implement pinning of cache usage for writeback [28/64] fscache: Provide a function to note the release of a page [29/64] fscache: Provide a function to resize a cookie [30/64] cachefiles: Introduce rewritten driver [31/64] cachefiles: Define structs [32/64] cachefiles: Add some error injection support [33/64] cachefiles: Add a couple of tracepoints for logging errors [34/64] cachefiles: Add cache error reporting macro [35/64] cachefiles: Add security derivation [36/64] cachefiles: Register a miscdev and parse commands over it [37/64] cachefiles: Provide a function to check how much space there is [38/64] vfs, cachefiles: Mark a backing file in use with an inode flag [39/64] cachefiles: Implement a function to get/create a directory in the cache [40/64] cachefiles: Implement cache registration and withdrawal [41/64] cachefiles: Implement volume support [42/64] cachefiles: Add tracepoints for calls to the VFS [43/64] cachefiles: Implement object lifecycle funcs [44/64] cachefiles: Implement key to filename encoding [45/64] cachefiles: Implement metadata/coherency data storage in xattrs [46/64] cachefiles: Mark a backing file in use with an inode flag [47/64] cachefiles: Implement culling daemon commands [48/64] cachefiles: Implement backing file wrangling [49/64] cachefiles: Implement begin and end I/O operation [50/64] cachefiles: Implement cookie resize for truncate [51/64] cachefiles: Implement the I/O routines [52/64] cachefiles: Allow cachefiles to actually function [53/64] fscache, cachefiles: Display stats of no-space events [54/64] fscache, cachefiles: Display stat of culling events [55/64] afs: Handle len being extending over page end in write_begin/write_end [56/64] afs: Fix afs_write_end() to handle len > page size [57/64] afs: Convert afs to use the new fscache API [58/64] afs: Copy local writes to the cache when writing to the server [59/64] afs: Skip truncation on the server of data we haven't written yet [60/64] 9p: Use fscache indexing rewrite and reenable caching [61/64] 9p: Copy local writes to the cache when writing to the server [62/64] nfs: Convert to new fscache volume/cookie API [63/64] cifs: Support fscache indexing rewrite (untested)

diff --git a/fs/cachefiles/Makefile b/fs/cachefiles/Makefile index 6f025940a65c..cb7a6bcf51eb 100644 --- a/fs/cachefiles/Makefile +++ b/fs/cachefiles/Makefile @@ -11,7 +11,8 @@ cachefiles-y := \ main.o \ namei.o \ security.o \ - volume.o + volume.o \ + xattr.o cachefiles-$(CONFIG_CACHEFILES_ERROR_INJECTION) += error_inject.o diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h index 28e386b5b1f3..fbb38d3e6cac 100644 --- a/fs/cachefiles/internal.h +++ b/fs/cachefiles/internal.h @@ -55,6 +55,7 @@ struct cachefiles_object { u8 d_name_len; /* Length of filename */ enum cachefiles_content content_info:8; /* Info about content presence */ unsigned long flags; +#define CACHEFILES_OBJECT_USING_TMPFILE 0 /* Have an unlinked tmpfile */ }; /* @@ -218,6 +219,17 @@ void cachefiles_acquire_volume(struct fscache_volume *volume); void cachefiles_free_volume(struct fscache_volume *volume); void cachefiles_withdraw_volume(struct cachefiles_volume *volume); +/* + * xattr.c + */ +extern int cachefiles_set_object_xattr(struct cachefiles_object *object); +extern int cachefiles_check_auxdata(struct cachefiles_object *object, + struct file *file); +extern int cachefiles_remove_object_xattr(struct cachefiles_cache *cache, + struct cachefiles_object *object, + struct dentry *dentry); +extern void cachefiles_prepare_to_write(struct fscache_cookie *cookie); + /* * Error handling */ @@ -228,6 +240,15 @@ do { \ set_bit(CACHEFILES_DEAD, &(___cache)->flags); \ } while (0) +#define cachefiles_io_error_obj(object, FMT, ...) \ +do { \ + struct cachefiles_cache *___cache; \ + \ + ___cache = (object)->volume->cache; \ + cachefiles_io_error(___cache, FMT " [o=%08x]", ##__VA_ARGS__, \ + (object)->debug_id); \ +} while (0) + /* * Debug tracing diff --git a/fs/cachefiles/xattr.c b/fs/cachefiles/xattr.c new file mode 100644 index 000000000000..0601c46a22ef --- /dev/null +++ b/fs/cachefiles/xattr.c @@ -0,0 +1,181 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* CacheFiles extended attribute management + * + * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include <linux/module.h> +#include <linux/sched.h> +#include <linux/file.h> +#include <linux/fs.h> +#include <linux/fsnotify.h> +#include <linux/quotaops.h> +#include <linux/xattr.h> +#include <linux/slab.h> +#include "internal.h" + +#define CACHEFILES_COOKIE_TYPE_DATA 1 + +struct cachefiles_xattr { + __be64 object_size; /* Actual size of the object */ + __be64 zero_point; /* Size after which server has no data not written by us */ + __u8 type; /* Type of object */ + __u8 content; /* Content presence (enum cachefiles_content) */ + __u8 data[]; /* netfs coherency data */ +} __packed; + +static const char cachefiles_xattr_cache[] = + XATTR_USER_PREFIX "CacheFiles.cache"; + +/* + * set the state xattr on a cache file + */ +int cachefiles_set_object_xattr(struct cachefiles_object *object) +{ + struct cachefiles_xattr *buf; + struct dentry *dentry; + struct file *file = object->file; + unsigned int len = object->cookie->aux_len; + int ret; + + if (!file) + return -ESTALE; + dentry = file->f_path.dentry; + + _enter("%x,#%d", object->debug_id, len); + + buf = kmalloc(sizeof(struct cachefiles_xattr) + len, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + buf->object_size = cpu_to_be64(object->cookie->object_size); + buf->zero_point = 0; + buf->type = CACHEFILES_COOKIE_TYPE_DATA; + buf->content = object->content_info; + if (test_bit(FSCACHE_COOKIE_LOCAL_WRITE, &object->cookie->flags)) + buf->content = CACHEFILES_CONTENT_DIRTY; + if (len > 0) + memcpy(buf->data, fscache_get_aux(object->cookie), len); + + ret = cachefiles_inject_write_error(); + if (ret == 0) + ret = vfs_setxattr(&init_user_ns, dentry, cachefiles_xattr_cache, + buf, sizeof(struct cachefiles_xattr) + len, 0); + if (ret < 0) { + trace_cachefiles_vfs_error(object, file_inode(file), ret, + cachefiles_trace_setxattr_error); + trace_cachefiles_coherency(object, file_inode(file)->i_ino, + buf->content, + cachefiles_coherency_set_fail); + if (ret != -ENOMEM) + cachefiles_io_error_obj( + object, + "Failed to set xattr with error %d", ret); + } else { + trace_cachefiles_coherency(object, file_inode(file)->i_ino, + buf->content, + cachefiles_coherency_set_ok); + } + + kfree(buf); + _leave(" = %d", ret); + return ret; +} + +/* + * check the consistency between the backing cache and the FS-Cache cookie + */ +int cachefiles_check_auxdata(struct cachefiles_object *object, struct file *file) +{ + struct cachefiles_xattr *buf; + struct dentry *dentry = file->f_path.dentry; + unsigned int len = object->cookie->aux_len, tlen; + const void *p = fscache_get_aux(object->cookie); + enum cachefiles_coherency_trace why; + ssize_t xlen; + int ret = -ESTALE; + + tlen = sizeof(struct cachefiles_xattr) + len; + buf = kmalloc(tlen, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + xlen = cachefiles_inject_read_error(); + if (xlen == 0) + xlen = vfs_getxattr(&init_user_ns, dentry, cachefiles_xattr_cache, buf, tlen); + if (xlen != tlen) { + if (xlen < 0) + trace_cachefiles_vfs_error(object, file_inode(file), xlen, + cachefiles_trace_getxattr_error); + if (xlen == -EIO) + cachefiles_io_error_obj( + object, + "Failed to read aux with error %zd", xlen); + why = cachefiles_coherency_check_xattr; + } else if (buf->type != CACHEFILES_COOKIE_TYPE_DATA) { + why = cachefiles_coherency_check_type; + } else if (memcmp(buf->data, p, len) != 0) { + why = cachefiles_coherency_check_aux; + } else if (be64_to_cpu(buf->object_size) != object->cookie->object_size) { + why = cachefiles_coherency_check_objsize; + } else if (buf->content == CACHEFILES_CONTENT_DIRTY) { + // TODO: Begin conflict resolution + pr_warn("Dirty object in cache\n"); + why = cachefiles_coherency_check_dirty; + } else { + why = cachefiles_coherency_check_ok; + ret = 0; + } + + trace_cachefiles_coherency(object, file_inode(file)->i_ino, + buf->content, why); + kfree(buf); + return ret; +} + +/* + * remove the object's xattr to mark it stale + */ +int cachefiles_remove_object_xattr(struct cachefiles_cache *cache, + struct cachefiles_object *object, + struct dentry *dentry) +{ + int ret; + + ret = cachefiles_inject_remove_error(); + if (ret == 0) + ret = vfs_removexattr(&init_user_ns, dentry, cachefiles_xattr_cache); + if (ret < 0) { + trace_cachefiles_vfs_error(object, d_inode(dentry), ret, + cachefiles_trace_remxattr_error); + if (ret == -ENOENT || ret == -ENODATA) + ret = 0; + else if (ret != -ENOMEM) + cachefiles_io_error(cache, + "Can't remove xattr from %lu" + " (error %d)", + d_backing_inode(dentry)->i_ino, -ret); + } + + _leave(" = %d", ret); + return ret; +} + +/* + * Stick a marker on the cache object to indicate that it's dirty. + */ +void cachefiles_prepare_to_write(struct fscache_cookie *cookie) +{ + const struct cred *saved_cred; + struct cachefiles_object *object = cookie->cache_priv; + struct cachefiles_cache *cache = object->volume->cache; + + _enter("c=%08x", object->cookie->debug_id); + + if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) { + cachefiles_begin_secure(cache, &saved_cred); + cachefiles_set_object_xattr(object); + cachefiles_end_secure(cache, saved_cred); + } +} diff --git a/include/trace/events/cachefiles.h b/include/trace/events/cachefiles.h index 493afa7fbfec..47b584b3ffab 100644 --- a/include/trace/events/cachefiles.h +++ b/include/trace/events/cachefiles.h @@ -42,6 +42,19 @@ enum fscache_why_object_killed { FSCACHE_OBJECT_WAS_CULLED, }; +enum cachefiles_coherency_trace { + cachefiles_coherency_check_aux, + cachefiles_coherency_check_content, + cachefiles_coherency_check_dirty, + cachefiles_coherency_check_len, + cachefiles_coherency_check_objsize, + cachefiles_coherency_check_ok, + cachefiles_coherency_check_type, + cachefiles_coherency_check_xattr, + cachefiles_coherency_set_fail, + cachefiles_coherency_set_ok, +}; + enum cachefiles_trunc_trace { cachefiles_trunc_dio_adjust, cachefiles_trunc_expand_tmpfile, @@ -95,6 +108,18 @@ enum cachefiles_error_trace { EM(cachefiles_obj_see_withdraw_cookie, "SEE withdraw_cookie") \ E_(cachefiles_obj_see_withdrawal, "SEE withdrawal") +#define cachefiles_coherency_traces \ + EM(cachefiles_coherency_check_aux, "BAD aux ") \ + EM(cachefiles_coherency_check_content, "BAD cont") \ + EM(cachefiles_coherency_check_dirty, "BAD dirt") \ + EM(cachefiles_coherency_check_len, "BAD len ") \ + EM(cachefiles_coherency_check_objsize, "BAD osiz") \ + EM(cachefiles_coherency_check_ok, "OK ") \ + EM(cachefiles_coherency_check_type, "BAD type") \ + EM(cachefiles_coherency_check_xattr, "BAD xatt") \ + EM(cachefiles_coherency_set_fail, "SET fail") \ + E_(cachefiles_coherency_set_ok, "SET ok ") + #define cachefiles_trunc_traces \ EM(cachefiles_trunc_dio_adjust, "DIOADJ") \ EM(cachefiles_trunc_expand_tmpfile, "EXPTMP") \ @@ -130,6 +155,7 @@ enum cachefiles_error_trace { cachefiles_obj_kill_traces; cachefiles_obj_ref_traces; +cachefiles_coherency_traces; cachefiles_trunc_traces; cachefiles_error_traces; @@ -287,6 +313,36 @@ TRACE_EVENT(cachefiles_rename, __print_symbolic(__entry->why, cachefiles_obj_kill_traces)) ); +TRACE_EVENT(cachefiles_coherency, + TP_PROTO(struct cachefiles_object *obj, + ino_t ino, + enum cachefiles_content content, + enum cachefiles_coherency_trace why), + + TP_ARGS(obj, ino, content, why), + + /* Note that obj may be NULL */ + TP_STRUCT__entry( + __field(unsigned int, obj ) + __field(enum cachefiles_coherency_trace, why ) + __field(enum cachefiles_content, content ) + __field(u64, ino ) + ), + + TP_fast_assign( + __entry->obj = obj->debug_id; + __entry->why = why; + __entry->content = content; + __entry->ino = ino; + ), + + TP_printk("o=%08x %s i=%llx c=%u", + __entry->obj, + __print_symbolic(__entry->why, cachefiles_coherency_traces), + __entry->ino, + __entry->content) + ); + TRACE_EVENT(cachefiles_trunc, TP_PROTO(struct cachefiles_object *obj, struct inode *backer, loff_t from, loff_t to, enum cachefiles_trunc_trace why),

[45/64] cachefiles: Implement metadata/coherency data storage in xattrs

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