Re: Set nodatacow per file?

[David Sterba]

Hi,

On Mon, Feb 13, 2012 at 04:40:03PM +0900, dima wrote:
> Actually it is possible. Check out David's response to my question from 
> some time ago:
> http://permalink.gmane.org/gmane.comp.file-systems.btrfs/14227

this was a quick aid, please see attached file for an updated tool to set
the file flags, now added 'z' for NOCOMPRESS flag, and supports chattr
syntax plus all of the standard file flags.

Setting and unsetting nocow is done like 'fileflags +C file' or -C for
unseting. Without any + or - options it prints current state.


david

#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>

#ifndef FS_NOCOMP_FL
#define FS_NOCOMP_FL                    0x00000400 /* Don't compress */
#endif

#ifndef FS_NOCOW_FL
#define FS_NOCOW_FL                     0x00800000 /* Do not cow file */
#endif

struct flags_name {
        unsigned long   flag;
        const char      short_name;
        const char      *long_name;
};

static const struct flags_name flags[]={
        /* new */
        { FS_NOCOW_FL, 'C', "NOCOW" },
        { FS_NOCOMP_FL, 'z', "Not_Compressed" },
        /* current */
        { FS_SECRM_FL, 's', "Secure_Deletion" },
        { FS_UNRM_FL, 'u' , "Undelete" },
        { FS_SYNC_FL, 'S', "Synchronous_Updates" },
        { FS_DIRSYNC_FL, 'D', "Synchronous_Directory_Updates" },
        { FS_IMMUTABLE_FL, 'i', "Immutable" },
        { FS_APPEND_FL, 'a', "Append_Only" },
        { FS_NODUMP_FL, 'd', "No_Dump" },
        { FS_NOATIME_FL, 'A', "No_Atime" },
        { FS_COMPR_FL, 'c', "Compression_Requested" },
        { FS_COMPRBLK_FL, 'B', "Compressed_File" },
        { FS_DIRTY_FL, 'Z', "Compressed_Dirty_File" },
        { FS_ECOMPR_FL, 'E', "Compression_Error" },
        { FS_JOURNAL_DATA_FL, 'j', "Journaled_Data" },
        { FS_INDEX_FL, 'I', "Indexed_directory" },
        { FS_NOTAIL_FL, 't', "No_Tailmerging" },
        { FS_TOPDIR_FL, 'T', "Top_of_Directory_Hierarchies" },
        /* { EXT4_EXTENTS_FL, 'e', "Extents" }, */
        /* { EXT4_HUGE_FILE_FL, 'h', "Huge_file" }, */
};

static unsigned long to_set, to_unset;

unsigned long c2val(char c)
{
        int i;

        for(i=0;i<sizeof(flags)/sizeof(flags[0]);i++) {
                if(flags[i].short_name==c)
                        return flags[i].flag;
        }

        printf("Warning: flag '%c' not found\n", c);
        return 0;
}
void list_flags(unsigned long fflags)
{
        int i;

        printf("Flags:\n");
        for(i=0;i<sizeof(flags)/sizeof(flags[0]);i++) {
                if(fflags & flags[i].flag) {
                        printf(" %c %s\n",
                                flags[i].short_name,
                                flags[i].long_name);
                }
        }
}

void set_flag(const char* in)
{
        int i;

        for(i=0;i<strlen(in);i++) {
                to_set |= c2val(in[i]);
                printf(" set %c\n", in[i]);
        }
}

void unset_flag(const char* in)
{
        int i;

        for(i=0;i<strlen(in);i++) {
                to_unset |= c2val(in[i]);
                printf(" unset %c\n", in[i]);
        }
}

int main(int argc, char **argv)
{
        int ret;
        int optind;
        int modify=0;

        if (argc < 2) {
                printf("usage: %s [options] [--] file...\n", argv[0]);
                exit(1);
        }
        to_set = 0;
        to_unset = 0;
        for(optind=1;optind<argc;optind++) {
                char *o=argv[optind];
                if(o[0]=='-' && o[1]=='-') {
                        optind++;
                        break;
                } else if(o[0]=='-') {
                        unset_flag(o+1);
                        modify=1;
                } else if(o[0]=='+') {
                        set_flag(o+1);
                        modify=1;
                } else break;
        }

        for(;optind<argc;optind++) {
                unsigned long fflags;
                int fd = -1;

                if(fd!=-1) close(fd);
                fd = open(argv[optind], O_RDONLY);
                if (fd == -1) {
                        perror("open()");
                        continue;
                }
                ret = ioctl(fd, FS_IOC_GETFLAGS, &fflags);
                if (ret == -1) {
                        perror("ioctl(GETFLAGS)");
                        continue;
                }
                if(modify) {
                        fflags |= to_set;
                        fflags &= ~to_unset;
                        ret = ioctl(fd, FS_IOC_SETFLAGS, &fflags);
                        if (ret == -1) {
                                perror("ioctl(SETFLAGS)");
                                continue;
                        }
                }
                printf("File: %s\n", argv[optind]);
                list_flags(fflags);
                putchar('\n');
        }

        return 0;
}