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btrfs-progs: tune: properly open zoned devices for RW 

[BUG]
There is a report that, for zoned devices btrfstune is unable to convert
it to block group tree.

 # btrfstune /dev/nullb0 --convert-to-block-group-tree
 Error reading 1342193664, -1
 Error reading 1342193664, -1
 ERROR: cannot read chunk root
 ERROR: open ctree failed

[CAUSE]
For read-write opened zoned devices, all the read/write has to be
aligned to its sector size.

However btrfs stores its metadata by extent_buffer::data[], which has
all the structures before it, thus never aligned to zoned device sector
size.

Normally we would require btrfs_pread() and btrfs_pwrite() to do the
extra alignment, but during open_ctree(), we are not aware if a device
is zoned or not.

Thus we rely on if the fd is opened with O_DIRECT flag, if the fd has
O_DIRECT, then we would temporarily set fs_info->zoned for chunk tree
read.

Unforunately not all open_ctree_fd() callers have the flags set
properly, and btrfstune is one of the missing call site.

This makes all the read not properly aligned and cause read failure.

[FIX]
Just manually check if the target device is a zoned one, and set
O_DIRECT accordingly.

Issue: #765
Pull-request: #767
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2024-03-26 10:52:44 +10:30 committed by David Sterba
parent 9de25ff2ae
commit 738bb7f0f0
1 changed files with 5 additions and 1 deletions
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6
tune/main.c
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@ -29,6 +29,7 @@
#include "kernel-shared/transaction.h" #include "kernel-shared/transaction.h"
#include "kernel-shared/volumes.h" #include "kernel-shared/volumes.h"
#include "kernel-shared/free-space-tree.h" #include "kernel-shared/free-space-tree.h"
#include "kernel-shared/zoned.h"
#include "common/utils.h" #include "common/utils.h"
#include "common/open-utils.h" #include "common/open-utils.h"
#include "common/device-scan.h" #include "common/device-scan.h"
@ -194,6 +195,7 @@ int BOX_MAIN(btrfstune)(int argc, char *argv[])
u64 super_flags = 0; u64 super_flags = 0;
int quota = 0; int quota = 0;
int fd = -1; int fd = -1;
int oflags = O_RDWR;
btrfs_config_init(); btrfs_config_init();
@ -337,7 +339,9 @@ int BOX_MAIN(btrfstune)(int argc, char *argv[])
} }
} }
fd = open(device, O_RDWR); if (zoned_model(device) == ZONED_HOST_MANAGED)
oflags |= O_DIRECT;
fd = open(device, oflags);
if (fd < 0) { if (fd < 0) {
error("mount check: cannot open %s: %m", device); error("mount check: cannot open %s: %m", device);
ret = 1; ret = 1;