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zipl: use FIEMAP mapping ioctl if it exists

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zipl currently uses the FIBMAP ioctl to map blocks for the bootloader;
on XFS, if FIBMAP is requested on a reflinked file, it will fail -
and FIBMAP returns 0 in this case, which is indistinguishable from a
hole.  This causes boot to fail because the file is not mapped.

We can use the FIEMAP ioctl instead, which is able to map reflinked
files.  While FIEMAP is able to map entire extents at once, here we
simply use it to obtain the mapping block-by-block so that it fits
in with the current FIBMAP calls.

Fixes: https://github.com/ibm-s390-tools/s390-tools/issues/34
Closes: https://github.com/ibm-s390-tools/s390-tools/pull/36
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Tested-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
This commit is contained in:
Eric Sandeen
2018-09-12 09:40:22 -05:00
committed by Jan Höppner
parent 0a0b4c3826
commit 07e30951f8
1 changed files with 53 additions and 4 deletions
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57
zipl/src/disk.c
View File

@@ -21,6 +21,8 @@
#include <sys/sysmacros.h>
#include <sys/vfs.h>
#include <unistd.h>
#include <linux/fs.h>
#include <linux/fiemap.h>
#include "lib/util_proc.h"
@@ -550,8 +552,12 @@ disk_get_blocknum(int fd, int fd_is_basedisk, blocknum_t logical,
{
struct statfs buf;
blocknum_t phy_per_fs;
int mapped;
blocknum_t mapped;
int block;
int subblock;
int fiemap_size;
int map_offset;
struct fiemap *fiemap;
/* No file system: partition or raw disk */
if (info->fs_block_size == -1) {
@@ -576,12 +582,55 @@ disk_get_blocknum(int fd, int fd_is_basedisk, blocknum_t logical,
}
/* Get mapping in file system blocks */
phy_per_fs = info->fs_block_size / info->phy_block_size;
mapped = logical / phy_per_fs;
subblock = logical % phy_per_fs;
if (ioctl(fd, FIBMAP, &mapped)) {
error_reason("Could not get file mapping");
/* First try FIEMAP, more complicated to set up */
fiemap_size = sizeof(struct fiemap) + sizeof(struct fiemap_extent);
fiemap = misc_malloc(fiemap_size);
if (!fiemap)
return -1;
memset(fiemap, 0, fiemap_size);
fiemap->fm_extent_count = 1;
fiemap->fm_flags = FIEMAP_FLAG_SYNC;
/* fm_start, fm_length in bytes; logical is in physical block units */
fiemap->fm_start = logical * info->phy_block_size;
fiemap->fm_length = info->phy_block_size;
if (ioctl(fd, FS_IOC_FIEMAP, (unsigned long)fiemap)) {
/* FIEMAP failed, fall back to FIBMAP */
block = logical / phy_per_fs;
if (ioctl(fd, FIBMAP, &block)) {
error_reason("Could not get file mapping");
free(fiemap);
return -1;
}
mapped = block;
} else {
if (fiemap->fm_mapped_extents) {
if (fiemap->fm_extents[0].fe_flags &
FIEMAP_EXTENT_ENCODED) {
error_reason("File mapping is encoded");
free(fiemap);
return -1;
}
/*
* returned extent may start prior to our request
*/
map_offset = fiemap->fm_start -
fiemap->fm_extents[0].fe_logical;
mapped = fiemap->fm_extents[0].fe_physical +
map_offset;
/* set mapped to fs block units */
mapped = mapped / info->fs_block_size;
} else {
mapped = 0;
}
}
free(fiemap);
if (mapped == 0) {
/* This is a hole in the file */
*physical = 0;