Re: [PATCH 3/3] xfs_io: implement inode '-n' and [num] argument

[Brian Foster <bfoster@redhat.com>]

On Fri, Sep 25, 2015 at 03:07:47PM +0200, Carlos Maiolino wrote:
> "-n [num]" argument, will return to the user the next inode valid on the filesystem
> after [num].
> 
> Using [num] exclusive, will test if the inode [num] is a valid inode in the
> filesystem or not.
> 
> Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
> ---
>  io/open.c | 84 +++++++++++++++++++++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 74 insertions(+), 10 deletions(-)
> 
> diff --git a/io/open.c b/io/open.c
> index 57ff0bf..9f68de0 100644
> --- a/io/open.c
> +++ b/io/open.c
> @@ -762,6 +762,8 @@ inode_help(void)
>  " -l	-- Returns the largest inode number in the filesystem\n"
>  " -s	-- Returns the physical size (in bits) of the\n"
>  "	   largest inode number in the filesystem\n"
> +" -n	-- Return the next valid inode after [num]"
> +"[num]	   Check if the inode [num] exists in the filesystem"
>  "\n"));
>  }
>  
> @@ -774,18 +776,19 @@ inode_f(
>  	__s32			lastgrp = 0;
>  	__u64			last = 0;
>  	__u64			lastino = 0;
> -	struct xfs_inogrp	igroup[1024];
> -	struct xfs_fsop_bulkreq	bulkreq;
> +	__u64			userino = 0;
> +	char			*p;
>  	int			c;
>  	int			ret_lsize = 0;
>  	int			ret_largest = 0;
> +	int			ret_isvalid = 0;
> +	int			ret_next = 0;
> +	struct xfs_inogrp	igroup[1024];
> +	struct xfs_fsop_bulkreq	bulkreq;
> +	struct xfs_bstat	bstat;
>  
> -	bulkreq.lastip = &last;
> -	bulkreq.icount = 1024; /* maybe an user-defined value!? */
> -	bulkreq.ubuffer = &igroup;
> -	bulkreq.ocount = &count;
>  
> -	while ((c = getopt(argc, argv, "sl")) != EOF) {
> +	while ((c = getopt(argc, argv, "sln:")) != EOF) {
>  		switch (c) {
>  		case 's':
>  			ret_lsize = 1;
> @@ -793,12 +796,34 @@ inode_f(
>  		case 'l':
>  			ret_largest = 1;
>  			break;
> +		case 'n':
> +			ret_next = 1;
> +			userino = strtoull(optarg, &p, 10);
> +			break;
>  		default:
>  			return command_usage(&inode_cmd);
>  		}
>  	}
>  
> +	if ((optind < argc) && !(ret_next || ret_lsize || ret_largest)) {
> +		ret_isvalid = 1;
> +		userino = strtoull(argv[optind], &p, 10);
> +	}

So this appears to be the default behavior (validate whether an inode
exists). Perhaps this functionality should come first since that's the
core behavior for the command.

> +
> +	if (userino)
> +		if (*p != '\0') {
> +			printf("[num] must be a valid number\n");
> +			exitcode = 1;
> +			return 0;
> +		}
> +
>  	if (ret_lsize || ret_largest) {
> +
> +		bulkreq.lastip = &last;
> +		bulkreq.icount = 1024; /* User-defined maybe!? */
> +		bulkreq.ubuffer = &igroup;
> +		bulkreq.ocount = &count;
> +
>  		for (;;) {
>  			if (xfsctl(file->name, file->fd, XFS_IOC_FSINUMBERS,
>  					&bulkreq)) {
> @@ -806,7 +831,7 @@ inode_f(
>  				exitcode = 1;
>  				return 0;
>  			}
> -			if (count < XFS_INODES_PER_CHUNK && count > 0)
> +			if (count < 1024 && count > 0)
>  				lastgrp = count;

Ok, that sort of addresses my question on patch 1. I guess this is a
record count rather than an inode count as well. In that case, what
happens if the fs has an exact multiple of 1024 inode records?

BTW, I think this should probably be set correctly when it is introduced
rather than set to a value and changed in a subsequent patch.

>  			if (!count)
>  				break;
> @@ -822,8 +847,47 @@ inode_f(
>  		else
>  			printf(_("Largest inode: %llu\n"), lastino);
>  
> +		return 0;
> +	}
> +
> +	/* Setup bulkreq for -n or [num] only */
> +	last = userino;
> +	bulkreq.lastip = &last;
> +	bulkreq.icount = 1;
> +	bulkreq.ubuffer = &bstat;
> +	bulkreq.ocount = &count;
> +
> +	if (ret_next) {
> +		if (xfsctl(file->name, file->fd, XFS_IOC_FSBULKSTAT, &bulkreq)) {
> +			if (errno == EINVAL)
> +				printf("Invalid or non-existent inode\n");
> +			else
> +				perror("XFS_IOC_FSBULKSTAT");
> +			exitcode = 1;
> +			return 0;
> +		}
> +
> +		if (!bstat.bs_ino) {
> +			printf("There are no further inodes in the filesystem\n");
> +			return 0;
> +		}

The above should technically check the output count rather than the
inode number, right?

> +
> +		printf("Next inode: %llu\n", bstat.bs_ino);
> +		return 0;
>  	}
>  
> +	if (ret_isvalid) {
> +		if (xfsctl(file->name, file->fd, XFS_IOC_FSBULKSTAT_SINGLE, &bulkreq)) {
> +			if (errno == EINVAL) {
> +				printf("Invalid or non-existent inode number\n");

Is EINVAL returned in the non-existent case or ENOENT?

Brian

> +			} else
> +				perror("XFS_IOC_FSBULKSTAT_SINGLE");
> +			exitcode = 1;
> +			return 0;
> +		}
> +		printf("Valid inode: %llu\n", bstat.bs_ino);
> +		return 0;
> +	}
>  
>  	return 0;
>  }
> @@ -895,9 +959,9 @@ open_init(void)
>  
>  	inode_cmd.name = "inode";
>  	inode_cmd.cfunc = inode_f;
> -	inode_cmd.args = _("[-s | -l]");
> +	inode_cmd.args = _("[-s | -l | -n] [num]");
>  	inode_cmd.argmin = 1;
> -	inode_cmd.argmax = 1;
> +	inode_cmd.argmax = 2;
>  	inode_cmd.flags = CMD_NOMAP_OK;
>  	inode_cmd.oneline =
>  		_("Query inode number usage in the filesystem");
> -- 
> 2.4.3
> 
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