On 08/14/2011 08:39 AM, Vasiliy Kulikov wrote:
Hi Glauber, On Sun, Aug 14, 2011 at 19:13 +0400, Glauber Costa wrote:+/** + * Generic option parsing for the VFS. + * + * Since most of the filesystems already do their own option parsing, and with + * very few code shared between them, this function strips out any options that + * we succeed in parsing ourselves. Passing them forward would just give the + * underlying fs an option it does not expect, leading it to fail. + * + * We don't yet have a pointer to the super block as well, since this is + * pre-mount. We accumulate in struct vfs_options whatever data we collected, + * and act on it later. + */ +static int vfs_parse_options(char *options, struct vfs_options *ops) +{ + substring_t args[MAX_OPT_ARGS]; + int option; + char *p; + char *opt; + char *start = NULL; + int ret; + + if (!options) + return 0; + + opt = kstrdup(options, GFP_KERNEL); + if (!opt) + return 1; + + ret = 1; + + start = opt; + while ((p = strsep(&opt, ",")) != NULL) { + int token; + if (!*p) + continue; + + /* + * Initialize args struct so we know whether arg was + * found; some options take optional arguments. + */ + args[0].to = args[0].from = 0; + token = match_token(p, tokens, args); + switch (token) { + case 1: + if (!args[0].from) + break; + + if (match_int(&args[0],&option)) + break;What if there are 2 passed options and the second fails? mount -o vfs_dcache_size=XXX,vfs_dcache_size=CRAP<dev> <mntpoint> In this case you leave the second option and pass it to the fs option parser (as you already set ret=0), which is wrong. I think you should explicitly return 1 where you know the option is related to VFS, but you failed to parse it. It would look even simplier than current code.
Good point, thank you. I agree.
(Yes, this is a rare situation, but I can imagine some program that automatically adds mount options to the existing list and passes it to mount.)
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