Re: [PATCH v11 16/21] vfs,ext2: Remove CONFIG_EXT2_FS_XIP and rename CONFIG_FS_XIP to CONFIG_FS_DAX

From: Mathieu Desnoyers
Date: Thu Oct 16 2014 - 08:26:43 EST

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On 25-Sep-2014 04:33:33 PM, Matthew Wilcox wrote:
> The fewer Kconfig options we have the better. Use the generic
> CONFIG_FS_DAX to enable XIP support in ext2 as well as in the core.
>
> Signed-off-by: Matthew Wilcox <matthew.r.wilcox@xxxxxxxxx>
> ---
> fs/Kconfig | 21 ++++++++++++++-------
> fs/Makefile | 2 +-
> fs/ext2/Kconfig | 11 -----------
> fs/ext2/ext2.h | 2 +-
> fs/ext2/file.c | 4 ++--
> fs/ext2/super.c | 4 ++--
> include/linux/fs.h | 4 ++--
> 7 files changed, 22 insertions(+), 26 deletions(-)
>
> diff --git a/fs/Kconfig b/fs/Kconfig
> index 312393f..a9eb53d 100644
> --- a/fs/Kconfig
> +++ b/fs/Kconfig
> @@ -13,13 +13,6 @@ if BLOCK
> source "fs/ext2/Kconfig"
> source "fs/ext3/Kconfig"
> source "fs/ext4/Kconfig"
> -
> -config FS_XIP
> -# execute in place
> - bool
> - depends on EXT2_FS_XIP
> - default y
> -
> source "fs/jbd/Kconfig"
> source "fs/jbd2/Kconfig"
>
> @@ -40,6 +33,20 @@ source "fs/ocfs2/Kconfig"
> source "fs/btrfs/Kconfig"
> source "fs/nilfs2/Kconfig"
>
> +config FS_DAX
> + bool "Direct Access support"
> + depends on MMU
> + help
> + Direct Access (DAX) can be used on memory-backed block devices.
> + If the block device supports DAX and the filesystem supports DAX,
> + then you can avoid using the pagecache to buffer I/Os. Turning
> + on this option will compile in support for DAX; you will need to
> + mount the filesystem using the -o xip option.

There is a mismatch between the documentation file (earlier patch): -o
dax, and this config description: -o xip.

I guess we might want to switch the mount option to "-o dax" and
document it as such, and since it should be usable transparently for the
same use-cases "-o xip" was enabling, we might want to keep parsing of
"-o xip" in the code for backward compatibility.

Thoughts ?

Thanks,

Mathieu

> +
> + If you do not have a block device that is capable of using this,
> + or if unsure, say N. Saying Y will increase the size of the kernel
> + by about 2kB.
> +
> endif # BLOCK
>
> # Posix ACL utility routines
> diff --git a/fs/Makefile b/fs/Makefile
> index 0325ec3..df4a4cf 100644
> --- a/fs/Makefile
> +++ b/fs/Makefile
> @@ -28,7 +28,7 @@ obj-$(CONFIG_SIGNALFD) += signalfd.o
> obj-$(CONFIG_TIMERFD) += timerfd.o
> obj-$(CONFIG_EVENTFD) += eventfd.o
> obj-$(CONFIG_AIO) += aio.o
> -obj-$(CONFIG_FS_XIP) += dax.o
> +obj-$(CONFIG_FS_DAX) += dax.o
> obj-$(CONFIG_FILE_LOCKING) += locks.o
> obj-$(CONFIG_COMPAT) += compat.o compat_ioctl.o
> obj-$(CONFIG_BINFMT_AOUT) += binfmt_aout.o
> diff --git a/fs/ext2/Kconfig b/fs/ext2/Kconfig
> index 14a6780..c634874e 100644
> --- a/fs/ext2/Kconfig
> +++ b/fs/ext2/Kconfig
> @@ -42,14 +42,3 @@ config EXT2_FS_SECURITY
>
> If you are not using a security module that requires using
> extended attributes for file security labels, say N.
> -
> -config EXT2_FS_XIP
> - bool "Ext2 execute in place support"
> - depends on EXT2_FS && MMU
> - help
> - Execute in place can be used on memory-backed block devices. If you
> - enable this option, you can select to mount block devices which are
> - capable of this feature without using the page cache.
> -
> - If you do not use a block device that is capable of using this,
> - or if unsure, say N.
> diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
> index 5ecf570..b30c3bd 100644
> --- a/fs/ext2/ext2.h
> +++ b/fs/ext2/ext2.h
> @@ -380,7 +380,7 @@ struct ext2_inode {
> #define EXT2_MOUNT_NO_UID32 0x000200 /* Disable 32-bit UIDs */
> #define EXT2_MOUNT_XATTR_USER 0x004000 /* Extended user attributes */
> #define EXT2_MOUNT_POSIX_ACL 0x008000 /* POSIX Access Control Lists */
> -#ifdef CONFIG_FS_XIP
> +#ifdef CONFIG_FS_DAX
> #define EXT2_MOUNT_XIP 0x010000 /* Execute in place */
> #else
> #define EXT2_MOUNT_XIP 0
> diff --git a/fs/ext2/file.c b/fs/ext2/file.c
> index da8dc64..46b333d 100644
> --- a/fs/ext2/file.c
> +++ b/fs/ext2/file.c
> @@ -25,7 +25,7 @@
> #include "xattr.h"
> #include "acl.h"
>
> -#ifdef CONFIG_EXT2_FS_XIP
> +#ifdef CONFIG_FS_DAX
> static int ext2_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
> {
> return dax_fault(vma, vmf, ext2_get_block);
> @@ -109,7 +109,7 @@ const struct file_operations ext2_file_operations = {
> .splice_write = iter_file_splice_write,
> };
>
> -#ifdef CONFIG_EXT2_FS_XIP
> +#ifdef CONFIG_FS_DAX
> const struct file_operations ext2_xip_file_operations = {
> .llseek = generic_file_llseek,
> .read = new_sync_read,
> diff --git a/fs/ext2/super.c b/fs/ext2/super.c
> index 0393c6d..feb53d8 100644
> --- a/fs/ext2/super.c
> +++ b/fs/ext2/super.c
> @@ -287,7 +287,7 @@ static int ext2_show_options(struct seq_file *seq, struct dentry *root)
> seq_puts(seq, ",grpquota");
> #endif
>
> -#if defined(CONFIG_EXT2_FS_XIP)
> +#ifdef CONFIG_FS_DAX
> if (sbi->s_mount_opt & EXT2_MOUNT_XIP)
> seq_puts(seq, ",xip");
> #endif
> @@ -549,7 +549,7 @@ static int parse_options(char *options, struct super_block *sb)
> break;
> #endif
> case Opt_xip:
> -#ifdef CONFIG_EXT2_FS_XIP
> +#ifdef CONFIG_FS_DAX
> set_opt (sbi->s_mount_opt, XIP);
> #else
> ext2_msg(sb, KERN_INFO, "xip option not supported");
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index d73db11..e6b48cc 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1642,7 +1642,7 @@ struct super_operations {
> #define IS_IMA(inode) ((inode)->i_flags & S_IMA)
> #define IS_AUTOMOUNT(inode) ((inode)->i_flags & S_AUTOMOUNT)
> #define IS_NOSEC(inode) ((inode)->i_flags & S_NOSEC)
> -#ifdef CONFIG_FS_XIP
> +#ifdef CONFIG_FS_DAX
> #define IS_DAX(inode) ((inode)->i_flags & S_DAX)
> #else
> #define IS_DAX(inode) 0
> @@ -2488,7 +2488,7 @@ extern loff_t fixed_size_llseek(struct file *file, loff_t offset,
> extern int generic_file_open(struct inode * inode, struct file * filp);
> extern int nonseekable_open(struct inode * inode, struct file * filp);
>
> -#ifdef CONFIG_FS_XIP
> +#ifdef CONFIG_FS_DAX
> int dax_clear_blocks(struct inode *, sector_t block, long size);
> int dax_truncate_page(struct inode *, loff_t from, get_block_t);
> ssize_t dax_do_io(int rw, struct kiocb *, struct inode *, struct iov_iter *,
> --
> 2.1.0
>
> --
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>

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Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
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Next message: Jan Kara: "IO request merging"
Previous message: Russell King - ARM Linux: "Re: [PATCH 3.17-rc4 v7 0/6] arm: Implement arch_trigger_all_cpu_backtrace"
Next in thread: Matthew Wilcox: "Re: [PATCH v11 16/21] vfs,ext2: Remove CONFIG_EXT2_FS_XIP and rename CONFIG_FS_XIP to CONFIG_FS_DAX"
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