Currently DAX page fault locking is racy.
CPU0 (write fault) CPU1 (read fault)
__dax_fault() __dax_fault()
get_block(inode, block, &bh, 0) -> not mapped
get_block(inode, block, &bh, 0)
-> not mapped
if (!buffer_mapped(&bh))
if (vmf->flags & FAULT_FLAG_WRITE)
get_block(inode, block, &bh, 1) -> allocates blocks
if (page) -> no
if (!buffer_mapped(&bh))
if (vmf->flags & FAULT_FLAG_WRITE) {
} else {
dax_load_hole();
}
dax_insert_mapping()
And we are in a situation where we fail in dax_radix_entry() with -EIO.
Another problem with the current DAX page fault locking is that there is
no race-free way to clear dirty tag in the radix tree. We can always
end up with clean radix tree and dirty data in CPU cache.
We fix the first problem by introducing locking of exceptional radix
tree entries in DAX mappings acting very similarly to page lock and thus
synchronizing properly faults against the same mapping index. The same
lock can later be used to avoid races when clearing radix tree dirty
tag.
Reviewed-by: NeilBrown <neilb@suse.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
We will use lowest available bit in the radix tree exceptional entry for
locking of the entry. Define it. Also clean up definitions of DAX entry
type bits in DAX exceptional entries to use defined constants instead of
hardcoding numbers and cleanup checking of these bits to not rely on how
other bits in the entry are set.
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Currently the handling of huge pages for DAX is racy. For example the
following can happen:
CPU0 (THP write fault) CPU1 (normal read fault)
__dax_pmd_fault() __dax_fault()
get_block(inode, block, &bh, 0) -> not mapped
get_block(inode, block, &bh, 0)
-> not mapped
if (!buffer_mapped(&bh) && write)
get_block(inode, block, &bh, 1) -> allocates blocks
truncate_pagecache_range(inode, lstart, lend);
dax_load_hole();
This results in data corruption since process on CPU1 won't see changes
into the file done by CPU0.
The race can happen even if two normal faults race however with THP the
situation is even worse because the two faults don't operate on the same
entries in the radix tree and we want to use these entries for
serialization. So make THP support in DAX code depend on CONFIG_BROKEN
for now.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Currently dax_pmd_fault() decides to fill a PMD-sized hole only if
returned buffer has BH_Uptodate set. However that doesn't get set for
any mapping buffer so that branch is actually a dead code. The
BH_Uptodate check doesn't make any sense so just remove it.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
The distinction between PAGE_SIZE and PAGE_CACHE_SIZE was removed in
09cbfea mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release}
macros
The comments for the above functions described a distinction between
those, that is now redundant, so remove those paragraphs
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
In the truncate or hole-punch path in dax, we clear out sub-page ranges.
If these sub-page ranges are sector aligned and sized, we can do the
zeroing through the driver instead so that error-clearing is handled
automatically.
For sub-sector ranges, we still have to rely on clear_pmem and have the
possibility of tripping over errors.
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
This allows XFS to perform zeroing using the iomap infrastructure and
avoid buffer heads.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>
[vishal: fix conflicts with dax-error-handling]
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
dax_clear_sectors() cannot handle poisoned blocks. These must be
zeroed using the BIO interface instead. Convert ext2 and XFS to use
only sb_issue_zerout().
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
[vishal: Also remove the dax_clear_sectors function entirely]
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
1/ If a mapping overlaps a bad sector fail the request.
2/ Do not opportunistically report more dax-capable capacity than is
requested when errors present.
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
[vishal: fix a conflict with system RAM collision patches]
[vishal: add a 'size' parameter to ->direct_access]
[vishal: fix a conflict with DAX alignment check patches]
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
In preparation for consulting a badblocks list in pmem_direct_access(),
teach dax_pmd_fault() to fallback rather than fail immediately upon
encountering an error. The thought being that reducing the span of the
dax request may avoid the error region.
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
blkdev_dax_capable() is similar to bdev_dax_supported(), but needs
to remain as a separate interface for checking dax capability of
a raw block device.
Rename and relocate blkdev_dax_capable() to keep them maintained
consistently, and call bdev_direct_access() for the dax capability
check.
There is no change in the behavior.
Link: https://lkml.org/lkml/2016/5/9/950
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <axboe@fb.com>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Boaz Harrosh <boaz@plexistor.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
When a partition is not aligned by 4KB, mount -o dax succeeds,
but any read/write access to the filesystem fails, except for
metadata update.
Call bdev_dax_supported() to perform proper precondition checks
which includes this partition alignment check.
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Boaz Harrosh <boaz@plexistor.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
When a partition is not aligned by 4KB, mount -o dax succeeds,
but any read/write access to the filesystem fails, except for
metadata update.
Call bdev_dax_supported() to perform proper precondition checks
which includes this partition alignment check.
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Boaz Harrosh <boaz@plexistor.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
When a partition is not aligned by 4KB, mount -o dax succeeds,
but any read/write access to the filesystem fails, except for
metadata update.
Call bdev_dax_supported() to perform proper precondition checks
which includes this partition alignment check.
Reported-by: Micah Parrish <micah.parrish@hpe.com>
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Jan Kara <jack@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Boaz Harrosh <boaz@plexistor.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
DAX imposes additional requirements to a device. Add
bdev_dax_supported() which performs all the precondition checks
necessary for filesystem to mount the device with dax option.
Also add a new check to verify if a partition is aligned by 4KB.
When a partition is unaligned, any dax read/write access fails,
except for metadata update.
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <axboe@fb.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Boaz Harrosh <boaz@plexistor.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
In preparation of moving DAX capability checks to the block layer
from filesystem code, add a VFS message interface that aligns with
filesystem's message format.
For instance, a vfs_msg() message followed by XFS messages in case
of a dax mount error may look like:
VFS (pmem0p1): error: unaligned partition for dax
XFS (pmem0p1): DAX unsupported by block device. Turning off DAX.
XFS (pmem0p1): Mounting V5 Filesystem
:
vfs_msg() is largely based on ext4_msg().
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <axboe@fb.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Boaz Harrosh <boaz@plexistor.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Callers of dax fault handlers must make sure these calls cannot race
with truncate. Thus it is enough to check inode size when entering the
function and we don't have to recheck it again later in the handler.
Note that inode size itself can be decreased while the fault handler
runs but filesystem locking prevents against any radix tree or block
mapping information changes resulting from the truncate and that is what
we really care about.
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
dax_do_io() is calling filemap_write_and_wait() if DIO_LOCKING flags is
set. Presumably this was copied over from direct IO code. However DAX
inodes have no pagecache pages to write so the call is pointless. Remove
it.
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
All the filesystems are now zeroing blocks themselves for DAX IO to avoid
races between dax_io() and dax_fault(). Remove the zeroing code from
dax_io() and add warning to catch the case when somebody unexpectedly
returns new or unwritten buffer.
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Now that all filesystems zero out blocks allocated for a fault handler,
we can just remove the zeroing from the handler itself. Also add checks
that no filesystem returns to us unwritten or new buffer.
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Currently ext2 zeroes any data blocks allocated for DAX inode however it
still returns them as BH_New. Thus DAX code zeroes them again in
dax_insert_mapping() which can possibly overwrite the data that has been
already stored to those blocks by a racing dax_io(). Avoid marking
pre-zeroed buffers as new.
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
When zeroing allocated blocks for DAX, we accidentally zeroed only the
first allocated block instead of all of them. So far this problem is
hidden by the fact that page faults always need only a single block and
DAX write code zeroes blocks again. But the zeroing in DAX code is racy
and needs to be removed so fix the zeroing in ext2 to zero all allocated
blocks.
Reported-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Fault handlers currently take complete_unwritten argument to convert
unwritten extents after PTEs are updated. However no filesystem uses
this anymore as the code is racy. Remove the unused argument.
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
These don't belong in radix-tree.c any more than PAGECACHE_TAG_* do.
Let's try to maintain the idea that radix-tree simply implements an
abstract data type.
Acked-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Currently ext4 treats DAX IO the same way as direct IO. I.e., it
allocates unwritten extents before IO is done and converts unwritten
extents afterwards. However this way DAX IO can race with page fault to
the same area:
ext4_ext_direct_IO() dax_fault()
dax_io()
get_block() - allocates unwritten extent
copy_from_iter_pmem()
get_block() - converts
unwritten block to
written and zeroes it
out
ext4_convert_unwritten_extents()
So data written with DAX IO gets lost. Similarly dax_new_buf() called
from dax_io() can overwrite data that has been already written to the
block via mmap.
Fix the problem by using pre-zeroed blocks for DAX IO the same way as we
use them for DAX mmap. The downside of this solution is that every
allocating write writes each block twice (once zeros, once data). Fixing
the race with locking is possible as well however we would need to
lock-out faults for the whole range written to by DAX IO. And that is
not easy to do without locking-out faults for the whole file which seems
too aggressive.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Currently ext4 direct IO handling is split between ext4_ext_direct_IO()
and ext4_ind_direct_IO(). However the extent based function calls into
the indirect based one for some cases and for example it is not able to
handle file extending. Previously it was not also properly handling
retries in case of ENOSPC errors. With DAX things would get even more
contrieved so just refactor the direct IO code and instead of indirect /
extent split do the split to read vs writes.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
When there are blocks to free in the running transaction, block
allocator can return ENOSPC although the filesystem has some blocks to
free. We use ext4_should_retry_alloc() to force commit of the current
transaction and return whether anything was committed so that it makes
sense to retry the allocation. However the transaction may get committed
after block allocation fails but before we call
ext4_should_retry_alloc(). So ext4_should_retry_alloc() returns false
because there is nothing to commit and we wrongly return ENOSPC.
Fix the race by unconditionally returning 1 from ext4_should_retry_alloc()
when we tried to commit a transaction. This should not add any
unnecessary retries since we had a transaction running a while ago when
trying to allocate blocks and we want to retry the allocation once that
transaction has committed anyway.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
ext4_dax_get_blocks() was accidentally omitted fixing get blocks
handlers to properly handle transient ENOSPC errors. Fix it now to use
ext4_get_blocks_trans() helper which takes care of these errors.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Currently, __dax_fault() does not call get_blocks() callback with create
argument set, when we got back unwritten extent from the initial
get_blocks() call during a write fault. This is because originally
filesystems were supposed to convert unwritten extents to written ones
using complete_unwritten() callback. Later this was abandoned in favor of
using pre-zeroed blocks however the condition whether get_blocks() needs
to be called with create == 1 remained.
Fix the condition so that filesystems are not forced to zero-out and
convert unwritten extents when get_blocks() is called with create == 0
(which introduces unnecessary overhead for read faults and can be
problematic as the filesystem may possibly be read-only).
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
ext4_find_extent(), stripped down to the parts relevant to this patch,
reads as
ppos = 0;
i = depth;
while (i) {
--i;
++ppos;
if (unlikely(ppos > depth)) {
...
ret = -EFSCORRUPTED;
goto err;
}
}
Due to the loop's bounds, the condition ppos > depth can never be met.
Remove this dead code.
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
ext4_io_submit() used to check for EOPNOTSUPP after bio submission,
which is why it had to get an extra reference to the bio before
submitting it. But since we no longer touch the bio after submission,
get rid of the redundant get/put of the bio. If we do get the extra
reference, we enter the slower path of having to flag this bio as now
having external references.
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Currently, in ext4_mb_init(), there's a loop like the following:
do {
...
offset += 1 << (sb->s_blocksize_bits - i);
i++;
} while (i <= sb->s_blocksize_bits + 1);
Note that the updated offset is used in the loop's next iteration only.
However, at the last iteration, that is at i == sb->s_blocksize_bits + 1,
the shift count becomes equal to (unsigned)-1 > 31 (c.f. C99 6.5.7(3))
and UBSAN reports
UBSAN: Undefined behaviour in fs/ext4/mballoc.c:2621:15
shift exponent 4294967295 is too large for 32-bit type 'int'
[...]
Call Trace:
[<ffffffff818c4d25>] dump_stack+0xbc/0x117
[<ffffffff818c4c69>] ? _atomic_dec_and_lock+0x169/0x169
[<ffffffff819411ab>] ubsan_epilogue+0xd/0x4e
[<ffffffff81941cac>] __ubsan_handle_shift_out_of_bounds+0x1fb/0x254
[<ffffffff81941ab1>] ? __ubsan_handle_load_invalid_value+0x158/0x158
[<ffffffff814b6dc1>] ? kmem_cache_alloc+0x101/0x390
[<ffffffff816fc13b>] ? ext4_mb_init+0x13b/0xfd0
[<ffffffff814293c7>] ? create_cache+0x57/0x1f0
[<ffffffff8142948a>] ? create_cache+0x11a/0x1f0
[<ffffffff821c2168>] ? mutex_lock+0x38/0x60
[<ffffffff821c23ab>] ? mutex_unlock+0x1b/0x50
[<ffffffff814c26ab>] ? put_online_mems+0x5b/0xc0
[<ffffffff81429677>] ? kmem_cache_create+0x117/0x2c0
[<ffffffff816fcc49>] ext4_mb_init+0xc49/0xfd0
[...]
Observe that the mentioned shift exponent, 4294967295, equals (unsigned)-1.
Unless compilers start to do some fancy transformations (which at least
GCC 6.0.0 doesn't currently do), the issue is of cosmetic nature only: the
such calculated value of offset is never used again.
Silence UBSAN by introducing another variable, offset_incr, holding the
next increment to apply to offset and adjust that one by right shifting it
by one position per loop iteration.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=114701
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=112161
Cc: stable@vger.kernel.org
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Currently, in mb_find_order_for_block(), there's a loop like the following:
while (order <= e4b->bd_blkbits + 1) {
...
bb += 1 << (e4b->bd_blkbits - order);
}
Note that the updated bb is used in the loop's next iteration only.
However, at the last iteration, that is at order == e4b->bd_blkbits + 1,
the shift count becomes negative (c.f. C99 6.5.7(3)) and UBSAN reports
UBSAN: Undefined behaviour in fs/ext4/mballoc.c:1281:11
shift exponent -1 is negative
[...]
Call Trace:
[<ffffffff818c4d35>] dump_stack+0xbc/0x117
[<ffffffff818c4c79>] ? _atomic_dec_and_lock+0x169/0x169
[<ffffffff819411bb>] ubsan_epilogue+0xd/0x4e
[<ffffffff81941cbc>] __ubsan_handle_shift_out_of_bounds+0x1fb/0x254
[<ffffffff81941ac1>] ? __ubsan_handle_load_invalid_value+0x158/0x158
[<ffffffff816e93a0>] ? ext4_mb_generate_from_pa+0x590/0x590
[<ffffffff816502c8>] ? ext4_read_block_bitmap_nowait+0x598/0xe80
[<ffffffff816e7b7e>] mb_find_order_for_block+0x1ce/0x240
[...]
Unless compilers start to do some fancy transformations (which at least
GCC 6.0.0 doesn't currently do), the issue is of cosmetic nature only: the
such calculated value of bb is never used again.
Silence UBSAN by introducing another variable, bb_incr, holding the next
increment to apply to bb and adjust that one by right shifting it by one
position per loop iteration.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=114701
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=112161
Cc: stable@vger.kernel.org
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
A failed call to dqget() returns an ERR_PTR() and not null. Fix
the check in ext4_ioctl_setproject() to handle this correctly.
Fixes: 9b7365fc1c ("ext4: add FS_IOC_FSSETXATTR/FS_IOC_FSGETXATTR interface support")
Cc: stable@vger.kernel.org # v4.5
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Instead of just printing warning messages, if the orphan list is
corrupted, declare the file system is corrupted. If there are any
reserved inodes in the orphaned inode list, declare the file system
corrupted and stop right away to avoid doing more potential damage to
the file system.
Cc: stable@vger.kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
If the orphaned inode list contains inode #5, ext4_iget() returns a
bad inode (since the bootloader inode should never be referenced
directly). Because of the bad inode, we end up processing the inode
repeatedly and this hangs the machine.
This can be reproduced via:
mke2fs -t ext4 /tmp/foo.img 100
debugfs -w -R "ssv last_orphan 5" /tmp/foo.img
mount -o loop /tmp/foo.img /mnt
(But don't do this if you are using an unpatched kernel if you care
about the system staying functional. :-)
This bug was found by the port of American Fuzzy Lop into the kernel
to find file system problems[1]. (Since it *only* happens if inode #5
shows up on the orphan list --- 3, 7, 8, etc. won't do it, it's not
surprising that AFL needed two hours before it found it.)
[1] http://events.linuxfoundation.org/sites/events/files/slides/AFL%20filesystem%20fuzzing%2C%20Vault%202016_0.pdf
Cc: stable@vger.kernel.org
Reported by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Messages passed to ext4_warning() or ext4_error() don't need trailing
newlines, because these function add the newlines themselves.
Signed-off-by: Jakub Wilk <jwilk@jwilk.net>
In ext4, there is a race condition between changing inode journal mode
and ext4_writepages(). While ext4_writepages() is executed on a
non-journalled mode inode, the inode's journal mode could be enabled
by ioctl() and then, some pages dirtied after switching the journal
mode will be still exposed to ext4_writepages() in non-journaled mode.
To resolve this problem, we use fs-wide per-cpu rw semaphore by Jan
Kara's suggestion because we don't want to waste ext4_inode_info's
space for this extra rare case.
Signed-off-by: Daeho Jeong <daeho.jeong@samsung.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
We already allocate delalloc blocks before changing the inode mode into
"per-file data journal" mode to prevent delalloc blocks from remaining
not allocated, but another issue concerned with "BH_Unwritten" status
still exists. For example, by fallocate(), several buffers' status
change into "BH_Unwritten", but these buffers cannot be processed by
ext4_alloc_da_blocks(). So, they still remain in unwritten status after
per-file data journaling is enabled and they cannot be changed into
written status any more and, if they are journaled and eventually
checkpointed, these unwritten buffer will cause a kernel panic by the
below BUG_ON() function of submit_bh_wbc() when they are submitted
during checkpointing.
static int submit_bh_wbc(int rw, struct buffer_head *bh,...
{
...
BUG_ON(buffer_unwritten(bh));
Moreover, when "dioread_nolock" option is enabled, the status of a
buffer is changed into "BH_Unwritten" after write_begin() completes and
the "BH_Unwritten" status will be cleared after I/O is done. Therefore,
if a buffer's status is changed into unwrutten but the buffer's I/O is
not submitted and completed, it can cause the same problem after
enabling per-file data journaling. You can easily generate this bug by
executing the following command.
./kvm-xfstests -C 10000 -m nodelalloc,dioread_nolock generic/269
To resolve these problems and define a boundary between the previous
mode and per-file data journaling mode, we need to flush and wait all
the I/O of buffers of a file before enabling per-file data journaling
of the file.
Signed-off-by: Daeho Jeong <daeho.jeong@samsung.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
The function jbd2_journal_extend() takes as its argument the number of
new credits to be added to the handle. We weren't taking into account
the currently unused handle credits; worse, we would try to extend the
handle by N credits when it had N credits available.
In the case where jbd2_journal_extend() fails because the transaction
is too large, when jbd2_journal_restart() gets called, the N credits
owned by the handle gets returned to the transaction, and the
transaction commit is asynchronously requested, and then
start_this_handle() will be able to successfully attach the handle to
the current transaction since the required credits are now available.
This is mostly harmless, but since ext4_ext_truncate_extend_restart()
returns EAGAIN, the truncate machinery will once again try to call
ext4_ext_truncate_extend_restart(), which will do the above sequence
over and over again until the transaction has committed.
This was found while I was debugging a lockup in caused by running
xfstests generic/074 in the data=journal case. I'm still not sure why
we ended up looping forever, which suggests there may still be another
bug hiding in the transaction accounting machinery, but this commit
prevents us from looping in the first place.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Currently we ask jbd2 to write all dirty allocated buffers before
committing a transaction when doing writeback of delay allocated blocks.
However this is unnecessary since we move all pages to writeback state
before dropping a transaction handle and then submit all the necessary
IO. We still need the transaction commit to wait for all the outstanding
writeback before flushing disk caches during transaction commit to avoid
data exposure issues though. Use the new jbd2 capability and ask it to
only wait for outstanding writeback during transaction commit when
writing back data in ext4_writepages().
Tested-by: "HUANG Weller (CM/ESW12-CN)" <Weller.Huang@cn.bosch.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Currently when filesystem needs to make sure data is on permanent
storage before committing a transaction it adds inode to transaction's
inode list. During transaction commit, jbd2 writes back all dirty
buffers that have allocated underlying blocks and waits for the IO to
finish. However when doing writeback for delayed allocated data, we
allocate blocks and immediately submit the data. Thus asking jbd2 to
write dirty pages just unnecessarily adds more work to jbd2 possibly
writing back other redirtied blocks.
Add support to jbd2 to allow filesystem to ask jbd2 to only wait for
outstanding data writes before committing a transaction and thus avoid
unnecessary writes.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This flag is just duplicating what ext4_should_order_data() tells you
and is used in a single place. Furthermore it doesn't reflect changes to
inode data journalling flag so it may be possibly misleading. Just
remove it.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Huang has reported that in his powerfail testing he is seeing stale
block contents in some of recently allocated blocks although he mounts
ext4 in data=ordered mode. After some investigation I have found out
that indeed when delayed allocation is used, we don't add inode to
transaction's list of inodes needing flushing before commit. Originally
we were doing that but commit f3b59291a6 removed the logic with a
flawed argument that it is not needed.
The problem is that although for delayed allocated blocks we write their
contents immediately after allocating them, there is no guarantee that
the IO scheduler or device doesn't reorder things and thus transaction
allocating blocks and attaching them to inode can reach stable storage
before actual block contents. Actually whenever we attach freshly
allocated blocks to inode using a written extent, we should add inode to
transaction's ordered inode list to make sure we properly wait for block
contents to be written before committing the transaction. So that is
what we do in this patch. This also handles other cases where stale data
exposure was possible - like filling hole via mmap in
data=ordered,nodelalloc mode.
The only exception to the above rule are extending direct IO writes where
blkdev_direct_IO() waits for IO to complete before increasing i_size and
thus stale data exposure is not possible. For now we don't complicate
the code with optimizing this special case since the overhead is pretty
low. In case this is observed to be a performance problem we can always
handle it using a special flag to ext4_map_blocks().
CC: stable@vger.kernel.org
Fixes: f3b59291a6
Reported-by: "HUANG Weller (CM/ESW12-CN)" <Weller.Huang@cn.bosch.com>
Tested-by: "HUANG Weller (CM/ESW12-CN)" <Weller.Huang@cn.bosch.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
If a directory has a large number of empty blocks, iterating over all
of them can take a long time, leading to scheduler warnings and users
getting irritated when they can't kill a process in the middle of one
of these long-running readdir operations. Fix this by adding checks to
ext4_readdir() and ext4_htree_fill_tree().
This was reverted earlier due to a typo in the original commit where I
experimented with using signal_pending() instead of
fatal_signal_pending(). The test was in the wrong place if we were
going to return signal_pending() since we would end up returning
duplicant entries. See 9f2394c9be for a more detailed explanation.
Added fix as suggested by Linus to check for signal_pending() in
in the filldir() functions.
Reported-by: Benjamin LaHaise <bcrl@kvack.org>
Google-Bug-Id: 27880676
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Here are 3 small fixes 4.6-rc4. Two fix up some lz4 issues with big
endian systems, and the remaining one resolves a minor debugfs issue
that was reported.
All have been in linux-next with no reported issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-4.6-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull misc fixes from Greg KH:
"Here are three small fixes for 4.6-rc4.
Two fix up some lz4 issues with big endian systems, and the remaining
one resolves a minor debugfs issue that was reported.
All have been in linux-next with no reported issues"
* tag 'driver-core-4.6-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
lib: lz4: cleanup unaligned access efficiency detection
lib: lz4: fixed zram with lz4 on big endian machines
debugfs: Make automount point inodes permanently empty
These patches fix f2fs and fscrypto based on -rc3 bug fixes in ext4 crypto,
which have not yet been fully propagated as follows.
- use of dget_parent and file_dentry to avoid crashes
- disallow RCU-mode lookup in d_invalidate
- disallow -ENOMEM in the core data encryption path
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Merge tag 'for-linus-4.6-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs
Pull f2fs/fscrypto fixes from Jaegeuk Kim:
"In addition to f2fs/fscrypto fixes, I've added one patch which
prevents RCU mode lookup in d_revalidate, as Al mentioned.
These patches fix f2fs and fscrypto based on -rc3 bug fixes in ext4
crypto, which have not yet been fully propagated as follows.
- use of dget_parent and file_dentry to avoid crashes
- disallow RCU-mode lookup in d_invalidate
- disallow -ENOMEM in the core data encryption path"
* tag 'for-linus-4.6-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs:
ext4/fscrypto: avoid RCU lookup in d_revalidate
fscrypto: don't let data integrity writebacks fail with ENOMEM
f2fs: use dget_parent and file_dentry in f2fs_file_open
fscrypto: use dget_parent() in fscrypt_d_revalidate()
A lot of seqfile users seem to be using things like %pK that uses the
credentials of the current process, but that is actually completely
wrong for filesystem interfaces.
The unix semantics for permission checking files is to check permissions
at _open_ time, not at read or write time, and that is not just a small
detail: passing off stdin/stdout/stderr to a suid application and making
the actual IO happen in privileged context is a classic exploit
technique.
So if we want to be able to look at permissions at read time, we need to
use the file open credentials, not the current ones. Normal file
accesses can just use "f_cred" (or any of the helper functions that do
that, like file_ns_capable()), but the seqfile interfaces do not have
any such options.
It turns out that seq_file _does_ save away the user_ns information of
the file, though. Since user_ns is just part of the full credential
information, replace that special case with saving off the cred pointer
instead, and suddenly seq_file has all the permission information it
needs.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As Al pointed, d_revalidate should return RCU lookup before using d_inode.
This was originally introduced by:
commit 34286d6662 ("fs: rcu-walk aware d_revalidate method").
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: stable <stable@vger.kernel.org>
