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Message-ID: <20141016121802.GK19075@thinkos.etherlink>
Date: Thu, 16 Oct 2014 14:18:02 +0200
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: Matthew Wilcox <matthew.r.wilcox@...el.com>
Cc: linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v11 13/21] ext2: Remove ext2_xip_verify_sb()
On 25-Sep-2014 04:33:30 PM, Matthew Wilcox wrote:
> Jan Kara pointed out that calling ext2_xip_verify_sb() in ext2_remount()
> doesn't make sense, since changing the XIP option on remount isn't
> allowed. It also doesn't make sense to re-check whether blocksize is
> supported since it can't change between mounts.
By "doesn't make sense", do you mean it is never actually used, or that
it is possible for a current user to trigger issues by changing XIP
option on remount ? If it is the case, then this patch should probably
be flagged as a "Fix".
Thanks,
Mathieu
>
> Replace the call to ext2_xip_verify_sb() in ext2_fill_super() with the
> equivalent check and delete the definition.
>
> Signed-off-by: Matthew Wilcox <matthew.r.wilcox@...el.com>
> ---
> fs/ext2/super.c | 33 ++++++++++++---------------------
> fs/ext2/xip.c | 12 ------------
> fs/ext2/xip.h | 2 --
> 3 files changed, 12 insertions(+), 35 deletions(-)
>
> diff --git a/fs/ext2/super.c b/fs/ext2/super.c
> index b88edc0..d862031 100644
> --- a/fs/ext2/super.c
> +++ b/fs/ext2/super.c
> @@ -868,9 +868,6 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
> ((EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ?
> MS_POSIXACL : 0);
>
> - ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
> - EXT2_MOUNT_XIP if not */
> -
> if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV &&
> (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) ||
> EXT2_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
> @@ -900,11 +897,17 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
>
> blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
>
> - if (ext2_use_xip(sb) && blocksize != PAGE_SIZE) {
> - if (!silent)
> + if (sbi->s_mount_opt & EXT2_MOUNT_XIP) {
> + if (blocksize != PAGE_SIZE) {
> ext2_msg(sb, KERN_ERR,
> - "error: unsupported blocksize for xip");
> - goto failed_mount;
> + "error: unsupported blocksize for xip");
> + goto failed_mount;
> + }
> + if (!sb->s_bdev->bd_disk->fops->direct_access) {
> + ext2_msg(sb, KERN_ERR,
> + "error: device does not support xip");
> + goto failed_mount;
> + }
> }
>
> /* If the blocksize doesn't match, re-read the thing.. */
> @@ -1249,7 +1252,6 @@ static int ext2_remount (struct super_block * sb, int * flags, char * data)
> {
> struct ext2_sb_info * sbi = EXT2_SB(sb);
> struct ext2_super_block * es;
> - unsigned long old_mount_opt = sbi->s_mount_opt;
> struct ext2_mount_options old_opts;
> unsigned long old_sb_flags;
> int err;
> @@ -1274,22 +1276,11 @@ static int ext2_remount (struct super_block * sb, int * flags, char * data)
> sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
> ((sbi->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);
>
> - ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
> - EXT2_MOUNT_XIP if not */
> -
> - if ((ext2_use_xip(sb)) && (sb->s_blocksize != PAGE_SIZE)) {
> - ext2_msg(sb, KERN_WARNING,
> - "warning: unsupported blocksize for xip");
> - err = -EINVAL;
> - goto restore_opts;
> - }
> -
> es = sbi->s_es;
> - if ((sbi->s_mount_opt ^ old_mount_opt) & EXT2_MOUNT_XIP) {
> + if ((sbi->s_mount_opt ^ old_opts.s_mount_opt) & EXT2_MOUNT_XIP) {
> ext2_msg(sb, KERN_WARNING, "warning: refusing change of "
> "xip flag with busy inodes while remounting");
> - sbi->s_mount_opt &= ~EXT2_MOUNT_XIP;
> - sbi->s_mount_opt |= old_mount_opt & EXT2_MOUNT_XIP;
> + sbi->s_mount_opt ^= EXT2_MOUNT_XIP;
> }
> if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY)) {
> spin_unlock(&sbi->s_lock);
> diff --git a/fs/ext2/xip.c b/fs/ext2/xip.c
> index 132d4da..66ca113 100644
> --- a/fs/ext2/xip.c
> +++ b/fs/ext2/xip.c
> @@ -13,15 +13,3 @@
> #include "ext2.h"
> #include "xip.h"
>
> -void ext2_xip_verify_sb(struct super_block *sb)
> -{
> - struct ext2_sb_info *sbi = EXT2_SB(sb);
> -
> - if ((sbi->s_mount_opt & EXT2_MOUNT_XIP) &&
> - !sb->s_bdev->bd_disk->fops->direct_access) {
> - sbi->s_mount_opt &= (~EXT2_MOUNT_XIP);
> - ext2_msg(sb, KERN_WARNING,
> - "warning: ignoring xip option - "
> - "not supported by bdev");
> - }
> -}
> diff --git a/fs/ext2/xip.h b/fs/ext2/xip.h
> index e7b9f0a..87eeb04 100644
> --- a/fs/ext2/xip.h
> +++ b/fs/ext2/xip.h
> @@ -6,13 +6,11 @@
> */
>
> #ifdef CONFIG_EXT2_FS_XIP
> -extern void ext2_xip_verify_sb (struct super_block *);
> static inline int ext2_use_xip (struct super_block *sb)
> {
> struct ext2_sb_info *sbi = EXT2_SB(sb);
> return (sbi->s_mount_opt & EXT2_MOUNT_XIP);
> }
> #else
> -#define ext2_xip_verify_sb(sb) do { } while (0)
> #define ext2_use_xip(sb) 0
> #endif
> --
> 2.1.0
>
> --
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>
>
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
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