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2016-12-01ext4: get rid of ext4_sb_has_crypto()Eric Biggers2-6/+1
ext4_sb_has_crypto() just called through to ext4_has_feature_encrypt(), and all callers except one were already using the latter. So remove it and switch its one caller to ext4_has_feature_encrypt(). Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-12-01ext4: fix inode checksum calculation problem if i_extra_size is smallDaeho Jeong1-3/+2
We've fixed the race condition problem in calculating ext4 checksum value in commit b47820edd163 ("ext4: avoid modifying checksum fields directly during checksum veficationon"). However, by this change, when calculating the checksum value of inode whose i_extra_size is less than 4, we couldn't calculate the checksum value in a proper way. This problem was found and reported by Nix, Thank you. Reported-by: Nix <nix@esperi.org.uk> Signed-off-by: Daeho Jeong <daeho.jeong@samsung.com> Signed-off-by: Youngjin Gil <youngjin.gil@samsung.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-12-01ext4: warn when page is dirtied without buffersJan Kara1-0/+9
Warn when a page is dirtied without buffers (as that will likely lead to a crash in ext4_writepages()) or when it gets newly dirtied without the page being locked (as there is nothing that prevents buffers to get stripped just before calling set_page_dirty() under memory pressure). Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-29ext4: be more strict when verifying flags set via SETFLAGS ioctlsJan Kara2-5/+24
Currently we just silently ignore flags that we don't understand (or that cannot be manipulated) through EXT4_IOC_SETFLAGS and EXT4_IOC_FSSETXATTR ioctls. This makes it problematic for the unused flags to be used in future (some app may be inadvertedly setting them and we won't notice until the flag gets used). Also this is inconsistent with other filesystems like XFS or BTRFS which return EOPNOTSUPP when they see a flag they cannot set. ext4 has the additional problem that there are flags which are returned by EXT4_IOC_GETFLAGS ioctl but which cannot be modified via EXT4_IOC_SETFLAGS. So we have to be careful to ignore value of these flags and not fail the ioctl when they are set (as e.g. chattr(1) passes flags returned from EXT4_IOC_GETFLAGS to EXT4_IOC_SETFLAGS without any masking and thus we'd break this utility). Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-29ext4: add EXT4_JOURNAL_DATA_FL and EXT4_EXTENTS_FL to modifiable maskJan Kara2-1/+4
Add EXT4_JOURNAL_DATA_FL and EXT4_EXTENTS_FL to EXT4_FL_USER_MODIFIABLE to recognize that they are modifiable by userspace. So far we got away without having them there because ext4_ioctl_setflags() treats them in a special way. But it was really confusing like that. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-26ext4: fix mmp use after free during unmountEric Sandeen1-1/+1
In ext4_put_super, we call brelse on the buffer head containing the ext4 superblock, but then try to use it when we stop the mmp thread, because when the thread shuts down it does: write_mmp_block ext4_mmp_csum_set ext4_has_metadata_csum WARN_ON_ONCE(ext4_has_feature_metadata_csum(sb)...) which reaches into sb->s_fs_info->s_es->s_feature_ro_compat, which lives in the superblock buffer s_sbh which we just released. Fix this by moving the brelse down to a point where we are no longer using it. Reported-by: Wang Shu <shuwang@redhat.com> Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Andreas Dilger <adilger@dilger.ca>
2016-11-23ext4: Add select for CONFIG_FS_IOMAPJan Kara1-0/+1
When ext4 is compiled with DAX support, it now needs the iomap code. Add appropriate select to Kconfig. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-21ext4: avoid lockdep warning when inheriting encryption contextEric Biggers2-12/+23
On a lockdep-enabled kernel, xfstests generic/027 fails due to a lockdep warning when run on ext4 mounted with -o test_dummy_encryption: xfs_io/4594 is trying to acquire lock: (jbd2_handle ){++++.+}, at: [<ffffffff813096ef>] jbd2_log_wait_commit+0x5/0x11b but task is already holding lock: (jbd2_handle ){++++.+}, at: [<ffffffff813000de>] start_this_handle+0x354/0x3d8 The abbreviated call stack is: [<ffffffff813096ef>] ? jbd2_log_wait_commit+0x5/0x11b [<ffffffff8130972a>] jbd2_log_wait_commit+0x40/0x11b [<ffffffff813096ef>] ? jbd2_log_wait_commit+0x5/0x11b [<ffffffff8130987b>] ? __jbd2_journal_force_commit+0x76/0xa6 [<ffffffff81309896>] __jbd2_journal_force_commit+0x91/0xa6 [<ffffffff813098b9>] jbd2_journal_force_commit_nested+0xe/0x18 [<ffffffff812a6049>] ext4_should_retry_alloc+0x72/0x79 [<ffffffff812f0c1f>] ext4_xattr_set+0xef/0x11f [<ffffffff812cc35b>] ext4_set_context+0x3a/0x16b [<ffffffff81258123>] fscrypt_inherit_context+0xe3/0x103 [<ffffffff812ab611>] __ext4_new_inode+0x12dc/0x153a [<ffffffff812bd371>] ext4_create+0xb7/0x161 When a file is created in an encrypted directory, ext4_set_context() is called to set an encryption context on the new file. This calls ext4_xattr_set(), which contains a retry loop where the journal is forced to commit if an ENOSPC error is encountered. If the task actually were to wait for the journal to commit in this case, then it would deadlock because a handle remains open from __ext4_new_inode(), so the running transaction can't be committed yet. Fortunately, __jbd2_journal_force_commit() avoids the deadlock by not allowing the running transaction to be committed while the current task has it open. However, the above lockdep warning is still triggered. This was a false positive which was introduced by: 1eaa566d368b: jbd2: track more dependencies on transaction commit Fix the problem by passing the handle through the 'fs_data' argument to ext4_set_context(), then using ext4_xattr_set_handle() instead of ext4_xattr_set(). And in the case where no journal handle is specified and ext4_set_context() has to open one, add an ENOSPC retry loop since in that case it is the outermost transaction. Signed-off-by: Eric Biggers <ebiggers@google.com>
2016-11-21ext4: remove unused function ext4_aligned_io()Ross Zwisler1-7/+0
The last user of ext4_aligned_io() was the DAX path in ext4_direct_IO_write(). This usage was removed by Jan Kara's patch entitled "ext4: Rip out DAX handling from direct IO path". Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-21dax: rip out get_block based IO supportJan Kara3-338/+11
No one uses functions using the get_block callback anymore. Rip them out and update documentation. Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-21ext2: use iomap_zero_range() for zeroing truncated page in DAX pathJan Kara1-3/+8
Currently the last user of ext2_get_blocks() for DAX inodes was dax_truncate_page(). Convert that to iomap_zero_range() so that all DAX IO uses the iomap path. Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-21ext4: rip out DAX handling from direct IO pathJan Kara2-84/+15
Reads and writes for DAX inodes should no longer end up in direct IO code. Rip out the support and add a warning. Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-21ext4: convert DAX faults to iomap infrastructureJan Kara2-9/+14
Convert DAX faults to use iomap infrastructure. We would not have to start transaction in ext4_dax_fault() anymore since ext4_iomap_begin takes care of that but so far we do that to avoid lock inversion of transaction start with DAX entry lock which gets acquired in dax_iomap_fault() before calling ->iomap_begin handler. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-21ext4: avoid split extents for DAX writesJan Kara1-17/+0
Currently mapping of blocks for DAX writes happen with EXT4_GET_BLOCKS_PRE_IO flag set. That has a result that each ext4_map_blocks() call creates a separate written extent, although it could be merged to the neighboring extents in the extent tree. The reason for using this flag is that in case the extent is unwritten, we need to convert it to written one and zero it out. However this "convert mapped range to written" operation is already implemented by ext4_map_blocks() for the case of data writes into unwritten extent. So just use flags for that mode of operation, simplify the code, and avoid unnecessary split extents. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-21ext4: DAX iomap write supportJan Kara2-6/+160
Implement DAX writes using the new iomap infrastructure instead of overloading the direct IO path. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-21ext4: use iomap for zeroing blocks in DAX modeJan Kara1-2/+4
Use iomap infrastructure for zeroing blocks when in DAX mode. ext4_iomap_begin() handles read requests just fine and that's all that is needed for iomap_zero_range(). Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-21ext4: convert DAX reads to iomap infrastructureJan Kara3-1/+93
Implement basic iomap_begin function that handles reading and use it for DAX reads. Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-21ext4: only set S_DAX if DAX is really supportedJan Kara3-1/+24
Currently we have S_DAX set inode->i_flags for a regular file whenever ext4 is mounted with dax mount option. However in some cases we cannot really do DAX - e.g. when inode is marked to use data journalling, when inode data is being encrypted, or when inode is stored inline. Make sure S_DAX flag is appropriately set/cleared in these cases. Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-21ext4: factor out checks from ext4_file_write_iter()Jan Kara1-47/+50
Factor out checks of 'from' and whether we are overwriting out of ext4_file_write_iter() so that the function is easier to follow. Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-18ext4: add sanity checking to count_overhead()Theodore Ts'o1-3/+8
The commit "ext4: sanity check the block and cluster size at mount time" should prevent any problems, but in case the superblock is modified while the file system is mounted, add an extra safety check to make sure we won't overrun the allocated buffer. Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@vger.kernel.org
2016-11-18ext4: use more strict checks for inodes_per_block on mountTheodore Ts'o1-9/+6
Centralize the checks for inodes_per_block and be more strict to make sure the inodes_per_block_group can't end up being zero. Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Andreas Dilger <adilger@dilger.ca> Cc: stable@vger.kernel.org
2016-11-18ext4: fix in-superblock mount options processingTheodore Ts'o1-15/+23
Fix a large number of problems with how we handle mount options in the superblock. For one, if the string in the superblock is long enough that it is not null terminated, we could run off the end of the string and try to interpret superblocks fields as characters. It's unlikely this will cause a security problem, but it could result in an invalid parse. Also, parse_options is destructive to the string, so in some cases if there is a comma-separated string, it would be modified in the superblock. (Fortunately it only happens on file systems with a 1k block size.) Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@vger.kernel.org
2016-11-18ext4: sanity check the block and cluster size at mount timeTheodore Ts'o2-1/+17
If the block size or cluster size is insane, reject the mount. This is important for security reasons (although we shouldn't be just depending on this check). Ref: http://www.securityfocus.com/archive/1/539661 Ref: https://bugzilla.redhat.com/show_bug.cgi?id=1332506 Reported-by: Borislav Petkov <bp@alien8.de> Reported-by: Nikolay Borisov <kernel@kyup.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@vger.kernel.org
2016-11-15ext4: remove parameter from ext4_xattr_ibody_set()Eric Whitney1-6/+5
The parameter "handle" isn't used. Signed-off-by: Eric Whitney <enwlinux@gmail.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-15ext4: allow inode expansion for nojournal file systemsEric Whitney1-5/+7
Runs of xfstest ext4/022 on nojournal file systems result in failures because the inodes of some of its test files do not expand as expected. The cause is a conditional in ext4_mark_inode_dirty() that prevents inode expansion unless the test file system has a journal. Remove this unnecessary restriction. Signed-off-by: Eric Whitney <enwlinux@gmail.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-15ext4: use current_time() for inode timestampsDeepa Dinamani10-35/+31
CURRENT_TIME_SEC and CURRENT_TIME are not y2038 safe. current_time() will be transitioned to be y2038 safe along with vfs. current_time() returns timestamps according to the granularities set in the super_block. The granularity check in ext4_current_time() to call current_time() or CURRENT_TIME_SEC is not required. Use current_time() directly to obtain timestamps unconditionally, and remove ext4_current_time(). Quota files are assumed to be on the same filesystem. Hence, use current_time() for these files as well. Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Arnd Bergmann <arnd@arndb.de>
2016-11-15ext4: fix stack memory corruption with 64k block sizeChandan Rajendra1-1/+1
The number of 'counters' elements needed in 'struct sg' is super_block->s_blocksize_bits + 2. Presently we have 16 'counters' elements in the array. This is insufficient for block sizes >= 32k. In such cases the memcpy operation performed in ext4_mb_seq_groups_show() would cause stack memory corruption. Fixes: c9de560ded61f Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Jan Kara <jack@suse.cz> Cc: stable@vger.kernel.org
2016-11-15ext4: fix mballoc breakage with 64k block sizeChandan Rajendra1-1/+1
'border' variable is set to a value of 2 times the block size of the underlying filesystem. With 64k block size, the resulting value won't fit into a 16-bit variable. Hence this commit changes the data type of 'border' to 'unsigned int'. Fixes: c9de560ded61f Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Andreas Dilger <adilger@dilger.ca> Cc: stable@vger.kernel.org
2016-11-14ext4: don't lock buffer in ext4_commit_super if holding spinlockTheodore Ts'o1-2/+3
If there is an error reported in mballoc via ext4_grp_locked_error(), the code is holding a spinlock, so ext4_commit_super() must not try to lock the buffer head, or else it will trigger a BUG: BUG: sleeping function called from invalid context at ./include/linux/buffer_head.h:358 in_atomic(): 1, irqs_disabled(): 0, pid: 993, name: mount CPU: 0 PID: 993 Comm: mount Not tainted 4.9.0-rc1-clouder1 #62 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.8.1-0-g4adadbd-20150316_085822-nilsson.home.kraxel.org 04/01/2014 ffff880006423548 ffffffff81318c89 ffffffff819ecdd0 0000000000000166 ffff880006423558 ffffffff810810b0 ffff880006423580 ffffffff81081153 ffff880006e5a1a0 ffff88000690e400 0000000000000000 ffff8800064235c0 Call Trace: [<ffffffff81318c89>] dump_stack+0x67/0x9e [<ffffffff810810b0>] ___might_sleep+0xf0/0x140 [<ffffffff81081153>] __might_sleep+0x53/0xb0 [<ffffffff8126c1dc>] ext4_commit_super+0x19c/0x290 [<ffffffff8126e61a>] __ext4_grp_locked_error+0x14a/0x230 [<ffffffff81081153>] ? __might_sleep+0x53/0xb0 [<ffffffff812822be>] ext4_mb_generate_buddy+0x1de/0x320 Since ext4_grp_locked_error() calls ext4_commit_super with sync == 0 (and it is the only caller which does so), avoid locking and unlocking the buffer in this case. This can result in races with ext4_commit_super() if there are other problems (which is what commit 4743f83990614 was trying to address), but a Warning is better than BUG. Fixes: 4743f83990614 Cc: stable@vger.kernel.org # 4.9 Reported-by: Nikolay Borisov <kernel@kyup.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Jan Kara <jack@suse.cz>
2016-11-14ext4: allow ext4_ext_truncate() to return an errorTheodore Ts'o3-10/+11
Return errors to the caller instead of declaring the file system corrupted. Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Jan Kara <jack@suse.cz>
2016-11-14ext4: allow ext4_truncate() to return an errorTheodore Ts'o4-20/+36
This allows us to properly propagate errors back up to ext4_truncate()'s callers. This also means we no longer have to silently ignore some errors (e.g., when trying to add the inode to the orphan inode list). Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Jan Kara <jack@suse.cz>
2016-11-14Merge branch 'fscrypt' into originTheodore Ts'o7-85/+124
2016-11-14Merge branch 'dax-4.10-iomap-pmd' into originTheodore Ts'o11-433/+542
2016-11-14fscrypto: don't use on-stack buffer for key derivationEric Biggers1-3/+13
With the new (in 4.9) option to use a virtually-mapped stack (CONFIG_VMAP_STACK), stack buffers cannot be used as input/output for the scatterlist crypto API because they may not be directly mappable to struct page. get_crypt_info() was using a stack buffer to hold the output from the encryption operation used to derive the per-file key. Fix it by using a heap buffer. This bug could most easily be observed in a CONFIG_DEBUG_SG kernel because this allowed the BUG in sg_set_buf() to be triggered. Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-14fscrypto: don't use on-stack buffer for filename encryptionEric Biggers1-32/+21
With the new (in 4.9) option to use a virtually-mapped stack (CONFIG_VMAP_STACK), stack buffers cannot be used as input/output for the scatterlist crypto API because they may not be directly mappable to struct page. For short filenames, fname_encrypt() was encrypting a stack buffer holding the padded filename. Fix it by encrypting the filename in-place in the output buffer, thereby making the temporary buffer unnecessary. This bug could most easily be observed in a CONFIG_DEBUG_SG kernel because this allowed the BUG in sg_set_buf() to be triggered. Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-14fscrypt: Let fs select encryption index/tweakDavid Gstir5-13/+19
Avoid re-use of page index as tweak for AES-XTS when multiple parts of same page are encrypted. This will happen on multiple (partial) calls of fscrypt_encrypt_page on same page. page->index is only valid for writeback pages. Signed-off-by: David Gstir <david@sigma-star.at> Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-14fscrypt: Constify struct inode pointerDavid Gstir3-18/+18
Some filesystems, such as UBIFS, maintain a const pointer for struct inode. Signed-off-by: David Gstir <david@sigma-star.at> Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-14fscrypt: Enable partial page encryptionDavid Gstir5-24/+44
Not all filesystems work on full pages, thus we should allow them to hand partial pages to fscrypt for en/decryption. Signed-off-by: David Gstir <david@sigma-star.at> Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-14fscrypt: Allow fscrypt_decrypt_page() to function with non-writeback pagesDavid Gstir3-9/+12
Some filesystem might pass pages which do not have page->mapping->host set to the encrypted inode. We want the caller to explicitly pass the corresponding inode. Signed-off-by: David Gstir <david@sigma-star.at> Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-14fscrypt: Add in-place encryption modeDavid Gstir2-10/+21
ext4 and f2fs require a bounce page when encrypting pages. However, not all filesystems will need that (eg. UBIFS). This is handled via a flag on fscrypt_operations where a fs implementation can select in-place encryption over using a bounce page (which is the default). Signed-off-by: David Gstir <david@sigma-star.at> Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-11-10dax: Introduce IOMAP_FAULT flagJan Kara3-4/+6
Introduce a flag telling iomap operations whether they are handling a fault or other IO. That may influence behavior wrt inode size and similar things. Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dave Chinner <david@fromorbit.com>
2016-11-08dax: remove "depends on BROKEN" from FS_DAX_PMDRoss Zwisler1-1/+0
Now that DAX PMD faults are once again working and are now participating in DAX's radix tree locking scheme, allow their config option to be enabled. Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Dave Chinner <david@fromorbit.com>
2016-11-08xfs: use struct iomap based DAX PMD fault pathRoss Zwisler3-25/+6
Switch xfs_filemap_pmd_fault() from using dax_pmd_fault() to the new and improved dax_iomap_pmd_fault(). Also, now that it has no more users, remove xfs_get_blocks_dax_fault(). Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Dave Chinner <david@fromorbit.com>
2016-11-08dax: add struct iomap based DAX PMD supportRoss Zwisler3-50/+386
DAX PMDs have been disabled since Jan Kara introduced DAX radix tree based locking. This patch allows DAX PMDs to participate in the DAX radix tree based locking scheme so that they can be re-enabled using the new struct iomap based fault handlers. There are currently three types of DAX 4k entries: 4k zero pages, 4k DAX mappings that have an associated block allocation, and 4k DAX empty entries. The empty entries exist to provide locking for the duration of a given page fault. This patch adds three equivalent 2MiB DAX entries: Huge Zero Page (HZP) entries, PMD DAX entries that have associated block allocations, and 2 MiB DAX empty entries. Unlike the 4k case where we insert a struct page* into the radix tree for 4k zero pages, for HZP we insert a DAX exceptional entry with the new RADIX_DAX_HZP flag set. This is because we use a single 2 MiB zero page in every 2MiB hole mapping, and it doesn't make sense to have that same struct page* with multiple entries in multiple trees. This would cause contention on the single page lock for the one Huge Zero Page, and it would break the page->index and page->mapping associations that are assumed to be valid in many other places in the kernel. One difficult use case is when one thread is trying to use 4k entries in radix tree for a given offset, and another thread is using 2 MiB entries for that same offset. The current code handles this by making the 2 MiB user fall back to 4k entries for most cases. This was done because it is the simplest solution, and because the use of 2MiB pages is already opportunistic. If we were to try to upgrade from 4k pages to 2MiB pages for a given range, we run into the problem of how we lock out 4k page faults for the entire 2MiB range while we clean out the radix tree so we can insert the 2MiB entry. We can solve this problem if we need to, but I think that the cases where both 2MiB entries and 4K entries are being used for the same range will be rare enough and the gain small enough that it probably won't be worth the complexity. Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Dave Chinner <david@fromorbit.com>
2016-11-08dax: move put_(un)locked_mapping_entry() in dax.cRoss Zwisler1-25/+25
No functional change. The static functions put_locked_mapping_entry() and put_unlocked_mapping_entry() will soon be used in error cases in grab_mapping_entry(), so move their definitions above this function. Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Dave Chinner <david@fromorbit.com>
2016-11-08dax: move RADIX_DAX_* defines to dax.hRoss Zwisler2-15/+14
The RADIX_DAX_* defines currently mostly live in fs/dax.c, with just RADIX_DAX_ENTRY_LOCK being in include/linux/dax.h so it can be used in mm/filemap.c. When we add PMD support, though, mm/filemap.c will also need access to the RADIX_DAX_PTE type so it can properly construct a 4k sized empty entry. Instead of shifting the defines between dax.c and dax.h as they are individually used in other code, just move them wholesale to dax.h so they'll be available when we need them. Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Dave Chinner <david@fromorbit.com>
2016-11-08dax: dax_iomap_fault() needs to call iomap_end()Ross Zwisler1-8/+29
Currently iomap_end() doesn't do anything for DAX page faults for both ext2 and XFS. ext2_iomap_end() just checks for a write underrun, and xfs_file_iomap_end() checks to see if it needs to finish a delayed allocation. However, in the future iomap_end() calls might be needed to make sure we have balanced allocations, locks, etc. So, add calls to iomap_end() with appropriate error handling to dax_iomap_fault(). Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com> Suggested-by: Jan Kara <jack@suse.cz> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Dave Chinner <david@fromorbit.com>
2016-11-08dax: add dax_iomap_sector() helper functionRoss Zwisler1-3/+7
To be able to correctly calculate the sector from a file position and a struct iomap there is a complex little bit of logic that currently happens in both dax_iomap_actor() and dax_iomap_fault(). This will need to be repeated yet again in the DAX PMD fault handler when it is added, so break it out into a helper function. Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Dave Chinner <david@fromorbit.com>
2016-11-08dax: correct dax iomap code namespaceRoss Zwisler4-17/+17
The recently added DAX functions that use the new struct iomap data structure were named iomap_dax_rw(), iomap_dax_fault() and iomap_dax_actor(). These are actually defined in fs/dax.c, though, so should be part of the "dax" namespace and not the "iomap" namespace. Rename them to dax_iomap_rw(), dax_iomap_fault() and dax_iomap_actor() respectively. Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com> Suggested-by: Dave Chinner <david@fromorbit.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Dave Chinner <david@fromorbit.com>
2016-11-08dax: remove dax_pmd_fault()Ross Zwisler2-218/+1
dax_pmd_fault() is the old struct buffer_head + get_block_t based 2 MiB DAX fault handler. This fault handler has been disabled for several kernel releases, and support for PMDs will be reintroduced using the struct iomap interface instead. Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Dave Chinner <david@fromorbit.com>