On Fri, Sep 19, 2014 at 02:01:30AM -0700, Omar Sandoval wrote:
> The RCU-friendy string API used internally by BTRFS is generic enough for
> common use. This doesn't add any new functionality, but instead just moves the
> code and documents the existing API.
>
> Signed-off-by: Omar Sandoval <osan...@osandov.com>
One nit: shouldn't the returned rcu_string pointer have an __rcu
address space annotation?
With that fixed:
Reviewed-by: Josh Triplett <j...@joshtriplett.org>
> fs/btrfs/check-integrity.c | 6 +--
> fs/btrfs/dev-replace.c | 19 +++++-----
> fs/btrfs/disk-io.c | 6 +--
> fs/btrfs/extent_io.c | 4 +-
> fs/btrfs/ioctl.c | 4 +-
> fs/btrfs/raid56.c | 2 +-
> fs/btrfs/rcu-string.h | 56 ----------------------------
> fs/btrfs/scrub.c | 15 ++++----
> fs/btrfs/super.c | 2 +-
> fs/btrfs/volumes.c | 14 +++----
> include/linux/rcustring.h | 91
> ++++++++++++++++++++++++++++++++++++++++++++++
> 11 files changed, 128 insertions(+), 91 deletions(-)
> delete mode 100644 fs/btrfs/rcu-string.h
> create mode 100644 include/linux/rcustring.h
>
> diff --git a/fs/btrfs/check-integrity.c b/fs/btrfs/check-integrity.c
> index ce92ae3..4ccd7da 100644
> --- a/fs/btrfs/check-integrity.c
> +++ b/fs/btrfs/check-integrity.c
> @@ -94,6 +94,7 @@
> #include <linux/mutex.h>
> #include <linux/genhd.h>
> #include <linux/blkdev.h>
> +#include <linux/rcustring.h>
> #include "ctree.h"
> #include "disk-io.h"
> #include "hash.h"
> @@ -103,7 +104,6 @@
> #include "print-tree.h"
> #include "locking.h"
> #include "check-integrity.h"
> -#include "rcu-string.h"
>
> #define BTRFSIC_BLOCK_HASHTABLE_SIZE 0x10000
> #define BTRFSIC_BLOCK_LINK_HASHTABLE_SIZE 0x10000
> @@ -851,8 +851,8 @@ static int btrfsic_process_superblock_dev_mirror(
> printk_in_rcu(KERN_INFO "New initial S-block (bdev %p,
> %s)"
> " @%llu (%s/%llu/%d)\n",
> superblock_bdev,
> - rcu_str_deref(device->name), dev_bytenr,
> - dev_state->name, dev_bytenr,
> + rcu_string_dereference(device->name),
> + dev_bytenr, dev_state->name, dev_bytenr,
> superblock_mirror_num);
> list_add(&superblock_tmp->all_blocks_node,
> &state->all_blocks_list);
> diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
> index eea26e1..87d10cc 100644
> --- a/fs/btrfs/dev-replace.c
> +++ b/fs/btrfs/dev-replace.c
> @@ -25,6 +25,7 @@
> #include <linux/capability.h>
> #include <linux/kthread.h>
> #include <linux/math64.h>
> +#include <linux/rcustring.h>
> #include <asm/div64.h>
> #include "ctree.h"
> #include "extent_map.h"
> @@ -34,7 +35,6 @@
> #include "volumes.h"
> #include "async-thread.h"
> #include "check-integrity.h"
> -#include "rcu-string.h"
> #include "dev-replace.h"
> #include "sysfs.h"
>
> @@ -376,9 +376,9 @@ int btrfs_dev_replace_start(struct btrfs_root *root,
> printk_in_rcu(KERN_INFO
> "BTRFS: dev_replace from %s (devid %llu) to %s started\n",
> src_device->missing ? "<missing disk>" :
> - rcu_str_deref(src_device->name),
> + rcu_string_dereference(src_device->name),
> src_device->devid,
> - rcu_str_deref(tgt_device->name));
> + rcu_string_dereference(tgt_device->name));
>
> tgt_device->total_bytes = src_device->total_bytes;
> tgt_device->disk_total_bytes = src_device->disk_total_bytes;
> @@ -528,9 +528,10 @@ static int btrfs_dev_replace_finishing(struct
> btrfs_fs_info *fs_info,
> printk_in_rcu(KERN_ERR
> "BTRFS: btrfs_scrub_dev(%s, %llu, %s) failed
> %d\n",
> src_device->missing ? "<missing disk>" :
> - rcu_str_deref(src_device->name),
> + rcu_string_dereference(src_device->name),
> src_device->devid,
> - rcu_str_deref(tgt_device->name), scrub_ret);
> + rcu_string_dereference(tgt_device->name),
> + scrub_ret);
> btrfs_dev_replace_unlock(dev_replace);
> mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
> mutex_unlock(&root->fs_info->chunk_mutex);
> @@ -544,9 +545,9 @@ static int btrfs_dev_replace_finishing(struct
> btrfs_fs_info *fs_info,
> printk_in_rcu(KERN_INFO
> "BTRFS: dev_replace from %s (devid %llu) to %s)
> finished\n",
> src_device->missing ? "<missing disk>" :
> - rcu_str_deref(src_device->name),
> + rcu_string_dereference(src_device->name),
> src_device->devid,
> - rcu_str_deref(tgt_device->name));
> + rcu_string_dereference(tgt_device->name));
> tgt_device->is_tgtdev_for_dev_replace = 0;
> tgt_device->devid = src_device->devid;
> src_device->devid = BTRFS_DEV_REPLACE_DEVID;
> @@ -805,10 +806,10 @@ static int btrfs_dev_replace_kthread(void *data)
> printk_in_rcu(KERN_INFO
> "BTRFS: continuing dev_replace from %s (devid %llu) to
> %s @%u%%\n",
> dev_replace->srcdev->missing ? "<missing disk>" :
> - rcu_str_deref(dev_replace->srcdev->name),
> + rcu_string_dereference(dev_replace->srcdev->name),
> dev_replace->srcdev->devid,
> dev_replace->tgtdev ?
> - rcu_str_deref(dev_replace->tgtdev->name) :
> + rcu_string_dereference(dev_replace->tgtdev->name) :
> "<missing target disk>",
> (unsigned int)progress);
> }
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index a1d36e6..00f7441 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -31,6 +31,7 @@
> #include <linux/ratelimit.h>
> #include <linux/uuid.h>
> #include <linux/semaphore.h>
> +#include <linux/rcustring.h>
> #include <asm/unaligned.h>
> #include "ctree.h"
> #include "disk-io.h"
> @@ -44,7 +45,6 @@
> #include "free-space-cache.h"
> #include "inode-map.h"
> #include "check-integrity.h"
> -#include "rcu-string.h"
> #include "dev-replace.h"
> #include "raid56.h"
> #include "sysfs.h"
> @@ -3059,7 +3059,7 @@ static void btrfs_end_buffer_write_sync(struct
> buffer_head *bh, int uptodate)
>
> printk_ratelimited_in_rcu(KERN_WARNING "BTRFS: lost page write
> due to "
> "I/O error on %s\n",
> - rcu_str_deref(device->name));
> + rcu_string_dereference(device->name));
> /* note, we dont' set_buffer_write_io_error because we have
> * our own ways of dealing with the IO errors
> */
> @@ -3247,7 +3247,7 @@ static int write_dev_flush(struct btrfs_device *device,
> int wait)
>
> if (bio_flagged(bio, BIO_EOPNOTSUPP)) {
> printk_in_rcu("BTRFS: disabling barriers on dev %s\n",
> - rcu_str_deref(device->name));
> + rcu_string_dereference(device->name));
> device->nobarriers = 1;
> } else if (!bio_flagged(bio, BIO_UPTODATE)) {
> ret = -EIO;
> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> index af0359d..441dccd 100644
> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c
> @@ -11,6 +11,7 @@
> #include <linux/pagevec.h>
> #include <linux/prefetch.h>
> #include <linux/cleancache.h>
> +#include <linux/rcustring.h>
> #include "extent_io.h"
> #include "extent_map.h"
> #include "ctree.h"
> @@ -18,7 +19,6 @@
> #include "volumes.h"
> #include "check-integrity.h"
> #include "locking.h"
> -#include "rcu-string.h"
> #include "backref.h"
>
> static struct kmem_cache *extent_state_cache;
> @@ -2065,7 +2065,7 @@ int repair_io_failure(struct btrfs_fs_info *fs_info,
> u64 start,
> printk_ratelimited_in_rcu(KERN_INFO
> "BTRFS: read error corrected: ino %lu off %llu "
> "(dev %s sector %llu)\n", page->mapping->host->i_ino,
> - start, rcu_str_deref(dev->name), sector);
> + start, rcu_string_dereference(dev->name), sector);
>
> bio_put(bio);
> return 0;
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 8a8e298..9d4cd72 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -44,6 +44,7 @@
> #include <linux/uuid.h>
> #include <linux/btrfs.h>
> #include <linux/uaccess.h>
> +#include <linux/rcustring.h>
> #include "ctree.h"
> #include "disk-io.h"
> #include "transaction.h"
> @@ -53,7 +54,6 @@
> #include "locking.h"
> #include "inode-map.h"
> #include "backref.h"
> -#include "rcu-string.h"
> #include "send.h"
> #include "dev-replace.h"
> #include "props.h"
> @@ -1583,7 +1583,7 @@ static noinline int btrfs_ioctl_resize(struct file
> *file,
> new_size *= root->sectorsize;
>
> printk_in_rcu(KERN_INFO "BTRFS: new size for %s is %llu\n",
> - rcu_str_deref(device->name), new_size);
> + rcu_string_dereference(device->name), new_size);
>
> if (new_size > old_size) {
> trans = btrfs_start_transaction(root, 0);
> diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
> index 0a6b6e4..eecf738 100644
> --- a/fs/btrfs/raid56.c
> +++ b/fs/btrfs/raid56.c
> @@ -32,6 +32,7 @@
> #include <linux/list_sort.h>
> #include <linux/raid/xor.h>
> #include <linux/vmalloc.h>
> +#include <linux/rcustring.h>
> #include <asm/div64.h>
> #include "ctree.h"
> #include "extent_map.h"
> @@ -42,7 +43,6 @@
> #include "raid56.h"
> #include "async-thread.h"
> #include "check-integrity.h"
> -#include "rcu-string.h"
>
> /* set when additional merges to this rbio are not allowed */
> #define RBIO_RMW_LOCKED_BIT 1
> diff --git a/fs/btrfs/rcu-string.h b/fs/btrfs/rcu-string.h
> deleted file mode 100644
> index 9e111e4..0000000
> --- a/fs/btrfs/rcu-string.h
> +++ /dev/null
> @@ -1,56 +0,0 @@
> -/*
> - * Copyright (C) 2012 Red Hat. All rights reserved.
> - *
> - * This program is free software; you can redistribute it and/or
> - * modify it under the terms of the GNU General Public
> - * License v2 as published by the Free Software Foundation.
> - *
> - * This program is distributed in the hope that it will be useful,
> - * but WITHOUT ANY WARRANTY; without even the implied warranty of
> - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> - * General Public License for more details.
> - *
> - * You should have received a copy of the GNU General Public
> - * License along with this program; if not, write to the
> - * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
> - * Boston, MA 021110-1307, USA.
> - */
> -
> -struct rcu_string {
> - struct rcu_head rcu;
> - char str[0];
> -};
> -
> -static inline struct rcu_string *rcu_string_strdup(const char *src, gfp_t
> mask)
> -{
> - size_t len = strlen(src) + 1;
> - struct rcu_string *ret = kzalloc(sizeof(struct rcu_string) +
> - (len * sizeof(char)), mask);
> - if (!ret)
> - return ret;
> - strncpy(ret->str, src, len);
> - return ret;
> -}
> -
> -static inline void rcu_string_free(struct rcu_string *str)
> -{
> - if (str)
> - kfree_rcu(str, rcu);
> -}
> -
> -#define printk_in_rcu(fmt, ...) do { \
> - rcu_read_lock(); \
> - printk(fmt, __VA_ARGS__); \
> - rcu_read_unlock(); \
> -} while (0)
> -
> -#define printk_ratelimited_in_rcu(fmt, ...) do { \
> - rcu_read_lock(); \
> - printk_ratelimited(fmt, __VA_ARGS__); \
> - rcu_read_unlock(); \
> -} while (0)
> -
> -#define rcu_str_deref(rcu_str) ({ \
> - struct rcu_string *__str = rcu_dereference(rcu_str); \
> - __str->str; \
> -})
> diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
> index f4a41f3..62e335f 100644
> --- a/fs/btrfs/scrub.c
> +++ b/fs/btrfs/scrub.c
> @@ -18,6 +18,7 @@
>
> #include <linux/blkdev.h>
> #include <linux/ratelimit.h>
> +#include <linux/rcustring.h>
> #include "ctree.h"
> #include "volumes.h"
> #include "disk-io.h"
> @@ -27,7 +28,6 @@
> #include "extent_io.h"
> #include "dev-replace.h"
> #include "check-integrity.h"
> -#include "rcu-string.h"
> #include "raid56.h"
>
> /*
> @@ -519,7 +519,8 @@ static int scrub_print_warning_inode(u64 inum, u64
> offset, u64 root,
> printk_in_rcu(KERN_WARNING "BTRFS: %s at logical %llu on dev "
> "%s, sector %llu, root %llu, inode %llu, offset %llu, "
> "length %llu, links %u (path: %s)\n", swarn->errstr,
> - swarn->logical, rcu_str_deref(swarn->dev->name),
> + swarn->logical,
> + rcu_string_dereference(swarn->dev->name),
> (unsigned long long)swarn->sector, root, inum, offset,
> min(isize - offset, (u64)PAGE_SIZE), nlink,
> (char *)(unsigned long)ipath->fspath->val[i]);
> @@ -531,7 +532,7 @@ err:
> printk_in_rcu(KERN_WARNING "BTRFS: %s at logical %llu on dev "
> "%s, sector %llu, root %llu, inode %llu, offset %llu: path "
> "resolving failed with ret=%d\n", swarn->errstr,
> - swarn->logical, rcu_str_deref(swarn->dev->name),
> + swarn->logical, rcu_string_dereference(swarn->dev->name),
> (unsigned long long)swarn->sector, root, inum, offset, ret);
>
> free_ipath(ipath);
> @@ -595,7 +596,7 @@ static void scrub_print_warning(const char *errstr,
> struct scrub_block *sblock)
> "BTRFS: %s at logical %llu on dev %s, "
> "sector %llu: metadata %s (level %d) in tree "
> "%llu\n", errstr, swarn.logical,
> - rcu_str_deref(dev->name),
> + rcu_string_dereference(dev->name),
> (unsigned long long)swarn.sector,
> ref_level ? "node" : "leaf",
> ret < 0 ? -1 : ref_level,
> @@ -796,7 +797,7 @@ out:
> num_uncorrectable_read_errors);
> printk_ratelimited_in_rcu(KERN_ERR "BTRFS: "
> "unable to fixup (nodatasum) error at logical %llu on dev
> %s\n",
> - fixup->logical, rcu_str_deref(fixup->dev->name));
> + fixup->logical, rcu_string_dereference(fixup->dev->name));
> }
>
> btrfs_free_path(path);
> @@ -1198,7 +1199,7 @@ corrected_error:
> spin_unlock(&sctx->stat_lock);
> printk_ratelimited_in_rcu(KERN_ERR
> "BTRFS: fixed up error at logical %llu on dev
> %s\n",
> - logical, rcu_str_deref(dev->name));
> + logical, rcu_string_dereference(dev->name));
> }
> } else {
> did_not_correct_error:
> @@ -1207,7 +1208,7 @@ did_not_correct_error:
> spin_unlock(&sctx->stat_lock);
> printk_ratelimited_in_rcu(KERN_ERR
> "BTRFS: unable to fixup (regular) error at logical %llu
> on dev %s\n",
> - logical, rcu_str_deref(dev->name));
> + logical, rcu_string_dereference(dev->name));
> }
>
> out:
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index c4124de..cf4db62 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -42,6 +42,7 @@
> #include <linux/cleancache.h>
> #include <linux/ratelimit.h>
> #include <linux/btrfs.h>
> +#include <linux/rcustring.h>
> #include "delayed-inode.h"
> #include "ctree.h"
> #include "disk-io.h"
> @@ -54,7 +55,6 @@
> #include "volumes.h"
> #include "export.h"
> #include "compression.h"
> -#include "rcu-string.h"
> #include "dev-replace.h"
> #include "free-space-cache.h"
> #include "backref.h"
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 340a92d..8b1e5e8 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -27,6 +27,7 @@
> #include <linux/kthread.h>
> #include <linux/raid/pq.h>
> #include <linux/semaphore.h>
> +#include <linux/rcustring.h>
> #include <asm/div64.h>
> #include "ctree.h"
> #include "extent_map.h"
> @@ -37,7 +38,6 @@
> #include "raid56.h"
> #include "async-thread.h"
> #include "check-integrity.h"
> -#include "rcu-string.h"
> #include "math.h"
> #include "dev-replace.h"
> #include "sysfs.h"
> @@ -6323,7 +6323,7 @@ static int update_dev_stat_item(struct
> btrfs_trans_handle *trans,
> if (ret < 0) {
> printk_in_rcu(KERN_WARNING "BTRFS: "
> "error %d while searching for dev_stats item for device
> %s!\n",
> - ret, rcu_str_deref(device->name));
> + ret, rcu_string_dereference(device->name));
> goto out;
> }
>
> @@ -6334,7 +6334,7 @@ static int update_dev_stat_item(struct
> btrfs_trans_handle *trans,
> if (ret != 0) {
> printk_in_rcu(KERN_WARNING "BTRFS: "
> "delete too small dev_stats item for device %s
> failed %d!\n",
> - rcu_str_deref(device->name), ret);
> + rcu_string_dereference(device->name), ret);
> goto out;
> }
> ret = 1;
> @@ -6347,8 +6347,8 @@ static int update_dev_stat_item(struct
> btrfs_trans_handle *trans,
> &key, sizeof(*ptr));
> if (ret < 0) {
> printk_in_rcu(KERN_WARNING "BTRFS: "
> - "insert dev_stats item for device %s
> failed %d!\n",
> - rcu_str_deref(device->name), ret);
> + "insert dev_stats item for device %s
> failed %d!\n",
> + rcu_string_dereference(device->name),
> ret);
> goto out;
> }
> }
> @@ -6402,7 +6402,7 @@ static void btrfs_dev_stat_print_on_error(struct
> btrfs_device *dev)
> return;
> printk_ratelimited_in_rcu(KERN_ERR "BTRFS: "
> "bdev %s errs: wr %u, rd %u, flush %u, corrupt %u,
> gen %u\n",
> - rcu_str_deref(dev->name),
> + rcu_string_dereference(dev->name),
> btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_WRITE_ERRS),
> btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_READ_ERRS),
> btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_FLUSH_ERRS),
> @@ -6422,7 +6422,7 @@ static void btrfs_dev_stat_print_on_load(struct
> btrfs_device *dev)
>
> printk_in_rcu(KERN_INFO "BTRFS: "
> "bdev %s errs: wr %u, rd %u, flush %u, corrupt %u, gen %u\n",
> - rcu_str_deref(dev->name),
> + rcu_string_dereference(dev->name),
> btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_WRITE_ERRS),
> btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_READ_ERRS),
> btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_FLUSH_ERRS),
> diff --git a/include/linux/rcustring.h b/include/linux/rcustring.h
> new file mode 100644
> index 0000000..18980e9
> --- /dev/null
> +++ b/include/linux/rcustring.h
> @@ -0,0 +1,91 @@
> +/*
> + * RCU-friendly strings
> + *
> + * Copyright (C) 2012 Red Hat. All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, you can access it online at
> + * http://www.gnu.org/licenses/gpl-2.0.html.
> + */
> +
> +#ifndef _LINUX_RCUSTRING_H
> +#define _LINUX_RCUSTRING_H
> +
> +struct rcu_string {
> + struct rcu_head rcu;
> + char str[0];
> +};
> +
> +/**
> + * rcu_string_strdup() - create an RCU string from a string
> + * @src: The string to copy
> + * @flags: Flags for kmalloc
> + */
> +static inline struct rcu_string *rcu_string_strdup(const char *src, gfp_t
> flags)
> +{
> + struct rcu_string *ret;
> + size_t len = strlen(src) + 1;
> +
> + ret = kmalloc(sizeof(struct rcu_string) + (len * sizeof(char)), flags);
> + if (!ret)
> + return ret;
> + memcpy(ret->str, src, len);
> + return ret;
> +}
> +
> +/**
> + * rcu_string_free() - free an RCU string
> + * @str: The string
> + */
> +static inline void rcu_string_free(struct rcu_string *str)
> +{
> + if (str)
> + kfree_rcu(str, rcu);
> +}
> +
> +/*
> + * rcu_string_dereference() - dereference an RCU string
> + * @str: The string
> + *
> + * Like rcu_dereference, this must be done in an RCU critical section.
> + */
> +static inline char *rcu_string_dereference(struct rcu_string *rcu_str)
> +{
> + return rcu_dereference(rcu_str)->str;
> +}
> +
> +/**
> + * printk_in_rcu() - printk in an RCU read-side critical section
> + */
> +#define printk_in_rcu(fmt, ...) \
> +({ \
> + int __ret; \
> + rcu_read_lock(); \
> + __ret = printk(fmt, __VA_ARGS__); \
> + rcu_read_unlock(); \
> + __ret; \
> +})
> +
> +/**
> + * printk_ratelimited_in_rcu() - printk in an RCU read-side critical section
> + */
> +#define printk_ratelimited_in_rcu(fmt, ...) \
> +({ \
> + int __ret; \
> + rcu_read_lock(); \
> + __ret = printk_ratelimited(fmt, __VA_ARGS__); \
> + rcu_read_unlock(); \
> + __ret; \
> +})
> +
> +#endif
> --
> 2.1.0
>
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