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Date: Sat, 02 Feb 2008 01:54:41 -0700
From: Andreas Dilger <adilger@....com>
To: "Theodore Ts'o" <tytso@....edu>, linux-ext4@...r.kernel.org
Subject: Re: [PATCH][26/28] e2fsprogs-fiemap.patch
Add support for ioctl(FIEMAP) to filefrag. If the kernel supports FIEMAP
the filefrag program prefers this more efficient mechanism to get extent
information instead of repeated FIBMAP calls.
Signed-off-by: Kalpak Shah <kalpak@...sterfs.com>
Signed-off-by: Andreas Dilger <adilger@...sterfs.com>
Index: e2fsprogs-1.40.2/misc/filefrag.c
===================================================================
--- e2fsprogs-1.40.2.orig/misc/filefrag.c
+++ e2fsprogs-1.40.2/misc/filefrag.c
@@ -38,11 +38,47 @@ extern int optind;
#include <sys/vfs.h>
#include <sys/ioctl.h>
#include <linux/fd.h>
+#include <ext2fs/ext2_types.h>
int verbose = 0;
-#define FIBMAP _IO(0x00,1) /* bmap access */
-#define FIGETBSZ _IO(0x00,2) /* get the block size used for bmap */
+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_unused;
+ 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_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 FIBMAP _IO(0x00, 1) /* bmap access */
+#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*/
#define EXT4_EXTENTS_FL 0x00080000 /* Inode uses extents */
#define EXT3_IOC_GETFLAGS _IOR('f', 1, long)
@@ -71,6 +107,62 @@ static unsigned long get_bmap(int fd, un
return b;
}
+int filefrag_fiemap(int fd, int bs, int *num_extents)
+{
+ char buf[4096] = "";
+ struct fiemap *fiemap = (struct fiemap *)buf;
+ int count = (sizeof(buf) - sizeof(*fiemap)) /
+ sizeof(struct fiemap_extent);
+ __u64 logical_blk = 0, last_blk = 0;
+ unsigned long flags;
+ int tot_extents = 0;
+ int eof = 0;
+ int i;
+ int rc;
+
+ memset(fiemap, 0, sizeof(struct fiemap));
+ fiemap->fm_extent_count = count;
+ fiemap->fm_length = ~0ULL;
+ if (!verbose)
+ flags |= FIEMAP_FLAG_NUM_EXTENTS;
+
+ do {
+ fiemap->fm_length = ~0ULL;
+ fiemap->fm_flags = flags;
+ fiemap->fm_extent_count = count;
+ rc = ioctl (fd, EXT4_IOC_FIEMAP, (unsigned long) fiemap);
+ if (rc)
+ return rc;
+
+ if (!verbose) {
+ *num_extents = fiemap->fm_extent_count;
+ goto out;
+ }
+
+ for (i = 0; i < fiemap->fm_extent_count; i++) {
+ __u64 phy_blk;
+ unsigned long ext_len;
+
+ phy_blk = fiemap->fm_extents[i].fe_offset / bs;
+ ext_len = fiemap->fm_extents[i].fe_length / bs;
+ if (logical_blk && (phy_blk != last_blk+1))
+ printf("Discontinuity: Block %llu is at %llu "
+ "(was %llu)\n", logical_blk, phy_blk,
+ last_blk);
+ logical_blk += ext_len;
+ last_blk = phy_blk + ext_len - 1;
+ if (fiemap->fm_extents[i].fe_flags & FIEMAP_EXTENT_EOF)
+ eof = 1;
+ }
+ fiemap->fm_start += fiemap->fm_length;
+ tot_extents += fiemap->fm_extent_count;
+ } while (0);
+
+ *num_extents = tot_extents;
+out:
+ return 0;
+}
+
#define EXT2_DIRECT 12
static void frag_report(const char *filename)
@@ -86,7 +178,7 @@ static void frag_report(const char *file
unsigned long block, last_block = 0, numblocks, i;
long bpib; /* Blocks per indirect block */
long cylgroups;
- int discont = 0, expected;
+ int num_extents = 0, expected;
int is_ext2 = 0;
unsigned int flags;
@@ -135,7 +227,8 @@ static void frag_report(const char *file
if (ioctl(fd, EXT3_IOC_GETFLAGS, &flags) < 0)
flags = 0;
if (flags & EXT4_EXTENTS_FL) {
- printf("File is stored in extents format\n");
+ if (verbose)
+ printf("File is stored in extents format\n");
is_ext2 = 0;
}
if (verbose)
@@ -148,32 +241,36 @@ static void frag_report(const char *file
printf("First block: %lu\nLast block: %lu\n",
get_bmap(fd, 0), get_bmap(fd, numblocks - 1));
}
- for (i=0; i < numblocks; i++) {
- if (is_ext2 && last_block) {
- if (((i-EXT2_DIRECT) % bpib) == 0)
- last_block++;
- if (((i-EXT2_DIRECT-bpib) % (bpib*bpib)) == 0)
- last_block++;
- if (((i-EXT2_DIRECT-bpib-bpib*bpib) % (bpib*bpib*bpib)) == 0)
- last_block++;
- }
- block = get_bmap(fd, i);
- if (block == 0)
- continue;
- if (last_block && (block != last_block +1) ) {
- if (verbose)
- printf("Discontinuity: Block %ld is at %lu (was %lu)\n",
- i, block, last_block);
- discont++;
+ if (is_ext2 || (filefrag_fiemap(fd, bs, &num_extents) != 0)) {
+ for (i = 0; i < numblocks; i++) {
+ if (is_ext2 && last_block) {
+ if (((i-EXT2_DIRECT) % bpib) == 0)
+ last_block++;
+ if (((i-EXT2_DIRECT-bpib) % (bpib*bpib)) == 0)
+ last_block++;
+ if (((i-EXT2_DIRECT-bpib-bpib*bpib) %
+ (bpib*bpib*bpib)) == 0)
+ last_block++;
+ }
+ block = get_bmap(fd, i);
+ if (block == 0)
+ continue;
+ if (last_block && (block != last_block+1) ) {
+ if (verbose)
+ printf("Discontinuity: Block %ld is at "
+ "%lu (was %lu)\n",
+ i, block, last_block+1);
+ num_extents++;
+ }
+ last_block = block;
}
- last_block = block;
}
- if (discont==0)
+ if (num_extents == 1)
printf("%s: 1 extent found", filename);
else
- printf("%s: %d extents found", filename, discont+1);
+ printf("%s: %d extents found", filename, num_extents);
expected = (numblocks/((bs*8)-(fsinfo.f_files/8/cylgroups)-3))+1;
- if (is_ext2 && expected != discont+1)
+ if (is_ext2 && expected != num_extents)
printf(", perfection would be %d extent%s\n", expected,
(expected>1) ? "s" : "");
else
Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.
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