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| author |   Vishal Verma <vishal.l.verma@intel.com> | 2019-02-27 17:06:27 -0700 |
|---|---|---|
| committer |   Dan Williams <dan.j.williams@intel.com> | 2019-02-28 09:57:39 -0800 |
| commit | 9dedc73a4658ebcc0c9b58c3cb84e9ac80122213 (patch) | |
| tree | 99e5a2f80c5820914f912b43713ff13e983dd1c9 /drivers/nvdimm/btt.h | |
| parent | libnvdimm/btt: Remove unnecessary code in btt_freelist_init (diff) | |
| download | linux-dev-9dedc73a4658ebcc0c9b58c3cb84e9ac80122213.tar.xz linux-dev-9dedc73a4658ebcc0c9b58c3cb84e9ac80122213.zip | |
libnvdimm/btt: Fix LBA masking during 'free list' population
The Linux BTT implementation assumes that log entries will never have
the 'zero' flag set, and indeed it never sets that flag for log entries
itself.
However, the UEFI spec is ambiguous on the exact format of the LBA field
of a log entry, specifically as to whether it should include the
additional flag bits or not. While a zero bit doesn't make sense in the
context of a log entry, other BTT implementations might still have it set.
If an implementation does happen to have it set, we would happily read
it in as the next block to write to for writes. Since a high bit is set,
it pushes the block number out of the range of an 'arena', and we fail
such a write with an EIO.
Follow the robustness principle, and tolerate such implementations by
stripping out the zero flag when populating the free list during
initialization. Additionally, use the same stripped out entries for
detection of incomplete writes and map restoration that happens at this
stage.
Add a sysfs file 'log_zero_flags' that indicates the ability to accept
such a layout to userspace applications. This enables 'ndctl
check-namespace' to recognize whether the kernel is able to handle zero
flags, or whether it should attempt a fix-up under the --repair option.
Cc: Dan Williams <dan.j.williams@intel.com>
Reported-by: Dexuan Cui <decui@microsoft.com>
Reported-by: Pedro d'Aquino Filocre F S Barbuda <pbarbuda@microsoft.com>
Tested-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/nvdimm/btt.h')
| -rw-r--r-- | drivers/nvdimm/btt.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/nvdimm/btt.h b/drivers/nvdimm/btt.h index db3cb6d4d0d4..ddff49c707b0 100644 --- a/drivers/nvdimm/btt.h +++ b/drivers/nvdimm/btt.h @@ -44,6 +44,8 @@ #define ent_e_flag(ent) (!!(ent & MAP_ERR_MASK)) #define ent_z_flag(ent) (!!(ent & MAP_TRIM_MASK)) #define set_e_flag(ent) (ent |= MAP_ERR_MASK) +/* 'normal' is both e and z flags set */ +#define ent_normal(ent) (ent_e_flag(ent) && ent_z_flag(ent)) enum btt_init_state { INIT_UNCHECKED = 0, |