Re: [PATCH v11 13/21] ext2: Remove ext2_xip_verify_sb()

[Mathieu Desnoyers <mathieu.desnoyers@efficios.com>]

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@intel.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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