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Date: Wed, 26 Mar 2008 16:07:20 -0700
From: Mingming Cao <cmm@...ibm.com>
To: Eric Sandeen <sandeen@...hat.com>
Cc: ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH 0/3] fiemap patches (RFC/testing)
On Wed, 2008-03-26 at 10:37 -0500, Eric Sandeen wrote:
> Since Akira would like to use the fiemap ioctl for defrag, I thought I should
> put what I have so far out on the list, at least. This could go in the unstable
> part of the tree if you like, though I need to do more testing etc before it's
> really ready to go.
>
I added the patches to the unstable queue, just fyi.
> Also, below is a quick test application I was using with the ioctl.
>
> -Eric
>
>
> #include <stdio.h>
> #include <stdlib.h>
> #include <unistd.h>
> #include <fcntl.h>
> #include <string.h>
> #include <sys/ioctl.h>
> #include <sys/types.h>
> #include <sys/stat.h>
> #include <sys/vfs.h>
> #include <ext2fs/ext2_types.h>
>
> /*************************************************/
> /* All this should come from fiemap.h eventually */
> struct fiemap_extent {
> __u64 fe_offset; /* offset in bytes for the start of the extent */
> __u64 fe_length; /* length in bytes for the extent */
> __u32 fe_flags; /* returned FIEMAP_EXTENT_* flags for the extent */
> __u32 fe_lun; /* logical device number for extent (starting at 0) */
> };
>
> struct fiemap {
> __u64 fm_start; /* logical starting byte offset (in/out) */
> __u64 fm_length; /* logical length of map (in/out) */
> __u32 fm_flags; /* FIEMAP_FLAG_* flags for request (in/out) */
> __u32 fm_extent_count; /* number of extents in fm_extents (in/out) */
> __u64 fm_end_offset; /* logical offset of end of mapping in last ioctl */
> struct fiemap_extent fm_extents[0];
> };
>
> #define FIEMAP_FLAG_SYNC 0x00000001 /* sync file data before map */
> #define FIEMAP_FLAG_HSM_READ 0x00000002 /* get data from HSM before map */
> #define FIEMAP_FLAG_NUM_EXTENTS 0x00000004 /* return only number of extents */
> #define FIEMAP_FLAG_INCOMPAT 0xff000000 /* error for unknown flags in here */
> #define FIEMAP_FLAG_LUN_OFFSET 0x01000000 /* use lun offsets, instead of
> * logical file offsets */
>
> #define FIEMAP_EXTENT_HOLE 0x00000001 /* has no data or space allocation */
> #define FIEMAP_EXTENT_UNWRITTEN 0x00000002 /* space allocated, but no data */
> #define FIEMAP_EXTENT_UNMAPPED 0x00000004 /* has data but no space allocation*/
> #define FIEMAP_EXTENT_ERROR 0x00000008 /* mapping error, errno in fe_start*/
> #define FIEMAP_EXTENT_NO_DIRECT 0x00000010 /* cannot access data directly */
> #define FIEMAP_EXTENT_LAST 0x00000020 /* last extent in the file */
> #define FIEMAP_EXTENT_DELALLOC 0x00000040 /* has data but not yet written,
> must have EXTENT_UNKNOWN set */
> #define FIEMAP_EXTENT_SECONDARY 0x00000080 /* data (also) in secondary storage,
> not in primary if EXTENT_UNKNOWN*/
> #define FIEMAP_EXTENT_EOF 0x00000100 /* if fm_start+fm_len is beyond EOF*/
>
> #define FIGETBSZ _IO(0x00, 2) /* get the block size used for bmap */
> #define EXT4_IOC_FIEMAP _IOWR('f', 10, struct fiemap) /* get file extent info*/
>
> /* End of what should be coming from fiemap.h */
> /**********************************************/
>
>
> void usage(void)
> {
> printf("Usage: fiemap [-vrSCL] [-s start] [-l length] [-c buf count] [-m max] filename\n");
> printf(" -v : verbose mode\n");
> printf(" -r : raw output: print raw ioctl structure values\n");
> printf(" -S : set FIEMAP_FLAG_SYNC to sync before mapping\n");
> printf(" -C : set FIEMAP_FLAG_NUM_EXTENTS to only get extent count, not mapping\n");
> printf(" -L : set FIEMAP_FLAG_LUN_OFFSET to report extents in lun order\n");
> printf(" -s start : start of mapping in bytes (default 0)\n");
> printf(" -l length : length of mapping in bytes (default to end of file)\n");
> printf(" -c count : count of extents in ioctl input structure (default 32)\n");
> printf(" -m max : max nr of ioctls to call before exit (default 512)\n");
> exit(EXIT_FAILURE);
> }
>
> #define EXABYTES(x) ((long long)(x) << 60)
> #define PETABYTES(x) ((long long)(x) << 50)
> #define TERABYTES(x) ((long long)(x) << 40)
> #define GIGABYTES(x) ((long long)(x) << 30)
> #define MEGABYTES(x) ((long long)(x) << 20)
> #define KILOBYTES(x) ((long long)(x) << 10)
>
> long long
> cvtnum(char *s)
> {
> long long i;
> char *sp;
> int c;
>
> i = strtoll(s, &sp, 0);
> if (i == 0 && sp == s)
> return -1LL;
> if (*sp == '\0')
> return i;
> if (sp[1] != '\0')
> return -1LL;
>
> c = tolower(*sp);
> switch (c) {
> case 'k':
> return KILOBYTES(i);
> case 'm':
> return MEGABYTES(i);
> case 'g':
> return GIGABYTES(i);
> case 't':
> return TERABYTES(i);
> case 'p':
> return PETABYTES(i);
> case 'e':
> return EXABYTES(i);
> }
>
> return -1LL;
> }
>
> void show_extents_table(struct fiemap *fiemap, int blocksize, int start_extent, int *is_last)
> {
> unsigned int i;
> __u64 lstart;
>
> lstart = fiemap->fm_start;
> for (i = 0; i < fiemap->fm_extent_count; i++) {
> __u64 length = fiemap->fm_extents[i].fe_length;
> __u64 phys = fiemap->fm_extents[i].fe_offset;
> int flags = fiemap->fm_extents[i].fe_flags;
>
> printf("ext: %3u logical: [%8llu..%8llu] phys: %8llu..%8llu flags: 0x%03X tot: %llu\n",
> i + start_extent,
> lstart, lstart + length - 1,
> (phys / blocksize),
> (flags & FIEMAP_EXTENT_HOLE) ? 0 : (phys + length - 1) / blocksize,
> flags,
> (length / blocksize));
>
> lstart += length;
> if (fiemap->fm_extents[i].fe_flags & FIEMAP_EXTENT_LAST) {
> *is_last = 1;
> return; /* XXX should we? or should look for exents filled in past last? */
> }
> }
> }
>
> void show_extents_raw(struct fiemap *fiemap, int start_extent, int *is_last)
> {
> unsigned int i;
>
> for (i = 0; i < fiemap->fm_extent_count; i++) {
> printf("\tExtent %3u: start: %10lld length: %10lld flags 0x%03X lun %3u\n",
> i + start_extent,
> fiemap->fm_extents[i].fe_offset,
> fiemap->fm_extents[i].fe_length,
> fiemap->fm_extents[i].fe_flags,
> fiemap->fm_extents[i].fe_lun);
>
> if (fiemap->fm_extents[i].fe_flags & FIEMAP_EXTENT_LAST) {
> *is_last = 1;
> return; /* XXX should we? or should look for exents filled in past last? */
> }
> }
> }
>
> int main(int argc, char**argv)
> {
> int blocksize = 0; /* filesystem blocksize */
> uint count = 32; /* extent count */
> int countonly = 0; /* return only extent count? */
> int fd; /* file descriptor */
> int last = 0; /* last extent found */
> int lunwise = 0; /* return extents lun-wise */
> int maxioctls = 512; /* max ioctls to try */
> int opt;
> int rc;
> int raw = 0; /* raw output format */
> int sync = 0; /* sync file before mapping */
> int verbose = 0; /* verbose output */
> char *fname; /* filename to map */
> char *fiebuf; /* fiemap buffer / ioctl argument */
> __u64 lstart = 0; /* logical input mapping start */
> __u64 llength = ~0ULL;/* logical input mapping length */
> uint start_ext = 0; /* starting extent nr. for this batch */
> struct fiemap *fiemap;
>
>
> while ((opt = getopt(argc, argv, "s:l:c:m:rSCLv")) != -1) {
> switch(opt) {
> /* logical mapping offset */
> case 's':
> lstart = cvtnum(optarg);
> break;
> /* logical mapping length */
> case 'l':
> llength = cvtnum(optarg);
> break;
> /* count of extent buffers to send */
> case 'c':
> count = atoi(optarg);
> break;
> /* max nr. of ioctls to try (safety net) */
> case 'm':
> maxioctls = atoi(optarg);
> break;
> /* raw format output */
> case 'r':
> raw++;
> break;
> /* sync file before mapping */
> case 'S':
> sync++;
> break;
> /* count extents only, no details */
> case 'C':
> countonly++;
> break;
> /* return extents in lun order */
> case 'L':
> lunwise++;
> break;
> /* be verbose */
> case 'v':
> verbose++;
> break;
> default:
> usage();
> }
> }
>
> fname = argv[optind++];
> if (!fname)
> usage();
>
> /* The whole buffer, extent maps and all */
> fiebuf = malloc(sizeof (struct fiemap) + (count * sizeof(struct fiemap_extent)));
> if (!fiebuf) {
> perror("Could not allocate fiemap buffers");
> exit(1);
> }
>
> /* Just the header */
> fiemap = (struct fiemap *)fiebuf;
>
> fiemap->fm_start = lstart;
> fiemap->fm_length = llength;
> fiemap->fm_flags = 0;
> if (sync)
> fiemap->fm_flags |= FIEMAP_FLAG_SYNC;
> if (countonly)
> fiemap->fm_flags |= FIEMAP_FLAG_NUM_EXTENTS;
> if (lunwise)
> fiemap->fm_flags |= FIEMAP_FLAG_LUN_OFFSET;
>
> fiemap->fm_extent_count = count;
> fiemap->fm_end_offset = 0; /* output only */
>
> fd = open(fname, O_RDONLY);
> if (fd < 0) {
> perror("Can't open file");
> exit(1);
> }
>
> if (ioctl(fd, FIGETBSZ, &blocksize) < 0) {
> perror("Can't get block size");
> close(fd);
> return;
> }
>
> do {
> if (verbose)
> printf("Input: start %llu length %llu flags 0x%X count %u end_offset %lld\n",
> fiemap->fm_start, fiemap->fm_length,
> fiemap->fm_flags, fiemap->fm_extent_count,
> fiemap->fm_end_offset);
>
> rc = ioctl(fd, EXT4_IOC_FIEMAP, (unsigned long)fiemap);
> if (rc < 0) {
> perror("FIEMAP ioctl failed");
> close(fd);
> exit(1);
> }
>
> if (verbose)
> printf("Output: start %llu length %llu flags 0x%X count %u end_offset %lld\n",
> fiemap->fm_start, fiemap->fm_length,
> fiemap->fm_flags, fiemap->fm_extent_count,
> fiemap->fm_end_offset);
> if (raw)
> show_extents_raw(fiemap, start_ext, &last);
> else
> show_extents_table(fiemap, blocksize, start_ext, &last);
>
> start_ext += fiemap->fm_extent_count;
>
> /* Did we finish up the last of the reqest? */
> if (fiemap->fm_length >= llength)
> break;
> /* Set up the next call arguments */
> fiemap->fm_start += fiemap->fm_length;
> llength -= fiemap->fm_length;
> fiemap->fm_length = llength;
> fiemap->fm_extent_count = count;
>
> maxioctls--;
>
> } while (!last && maxioctls > 0);
>
> close(fd);
>
> return 0;
> }
>
> --
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