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

To: Carlos Maiolino <cmaiolino@xxxxxxxxxx>
Subject: Re: [PATCH 3/3] xfs_io: implement inode '-n' and [num] argument
From: Brian Foster <bfoster@xxxxxxxxxx>
Date: Tue, 6 Oct 2015 13:00:56 -0400
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1443186467-20110-4-git-send-email-cmaiolino@xxxxxxxxxx>
References: <1443186467-20110-1-git-send-email-cmaiolino@xxxxxxxxxx> <1443186467-20110-4-git-send-email-cmaiolino@xxxxxxxxxx>
User-agent: Mutt/1.5.23 (2014-03-12)
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@xxxxxxxxxx>
> ---
>  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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