* Refactor code paths involved with partial block zero-out in
prearation for converting ext4 to use iomap for buffered writes.
* Remove use of d_alloc() from ext4 in preparation for the deprecation
of this interface.
* Replace some J_ASSERTS with a journal abort so we can avoid a kernel
panic for a localized file system error
* Simplify various code paths in mballoc, move_extent, and fast commit
* Fix rare deadlock in jbd2_journal_cancel_revoke() that can be
triggered by generic/013 when blocksize < pagesize.
* Fix memory leak when releasing an extended attribute when its
value is stored in an ea_inode
* Fix various potential kunit test bugs in fs/ext4/extents.c
* Fix potential out-of-bounds access in check_xattr() with a corrupted
file system
* Make the jbd2_inode dirty range tracking safe for lockless reads
* Avoid a WARN_ON when writeback files due to a corrupted file system;
we already print an ext4 warning indicatign that data will be lost,
so the WARN_ON is not necessary and doesn't add any new information
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Merge tag 'ext4_for_linux-7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
Pull ext4 updates from Ted Ts'o:
- Refactor code paths involved with partial block zero-out in
prearation for converting ext4 to use iomap for buffered writes
- Remove use of d_alloc() from ext4 in preparation for the deprecation
of this interface
- Replace some J_ASSERTS with a journal abort so we can avoid a kernel
panic for a localized file system error
- Simplify various code paths in mballoc, move_extent, and fast commit
- Fix rare deadlock in jbd2_journal_cancel_revoke() that can be
triggered by generic/013 when blocksize < pagesize
- Fix memory leak when releasing an extended attribute when its value
is stored in an ea_inode
- Fix various potential kunit test bugs in fs/ext4/extents.c
- Fix potential out-of-bounds access in check_xattr() with a corrupted
file system
- Make the jbd2_inode dirty range tracking safe for lockless reads
- Avoid a WARN_ON when writeback files due to a corrupted file system;
we already print an ext4 warning indicatign that data will be lost,
so the WARN_ON is not necessary and doesn't add any new information
* tag 'ext4_for_linux-7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (37 commits)
jbd2: fix deadlock in jbd2_journal_cancel_revoke()
ext4: fix missing brelse() in ext4_xattr_inode_dec_ref_all()
ext4: fix possible null-ptr-deref in mbt_kunit_exit()
ext4: fix possible null-ptr-deref in extents_kunit_exit()
ext4: fix the error handling process in extents_kunit_init).
ext4: call deactivate_super() in extents_kunit_exit()
ext4: fix miss unlock 'sb->s_umount' in extents_kunit_init()
ext4: fix bounds check in check_xattrs() to prevent out-of-bounds access
ext4: zero post-EOF partial block before appending write
ext4: move pagecache_isize_extended() out of active handle
ext4: remove ctime/mtime update from ext4_alloc_file_blocks()
ext4: unify SYNC mode checks in fallocate paths
ext4: ensure zeroed partial blocks are persisted in SYNC mode
ext4: move zero partial block range functions out of active handle
ext4: pass allocate range as loff_t to ext4_alloc_file_blocks()
ext4: remove handle parameters from zero partial block functions
ext4: move ordered data handling out of ext4_block_do_zero_range()
ext4: rename ext4_block_zero_page_range() to ext4_block_zero_range()
ext4: factor out journalled block zeroing range
ext4: rename and extend ext4_block_truncate_page()
...
Please consider pulling these changes from the signed vfs-7.1-rc1.kino tag.
Thanks!
Christian
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Merge tag 'vfs-7.1-rc1.kino' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs i_ino updates from Christian Brauner:
"For historical reasons, the inode->i_ino field is an unsigned long,
which means that it's 32 bits on 32 bit architectures. This has caused
a number of filesystems to implement hacks to hash a 64-bit identifier
into a 32-bit field, and deprives us of a universal identifier field
for an inode.
This changes the inode->i_ino field from an unsigned long to a u64.
This shouldn't make any material difference on 64-bit hosts, but
32-bit hosts will see struct inode grow by at least 4 bytes. This
could have effects on slabcache sizes and field alignment.
The bulk of the changes are to format strings and tracepoints, since
the kernel itself doesn't care that much about the i_ino field. The
first patch changes some vfs function arguments, so check that one out
carefully.
With this change, we may be able to shrink some inode structures. For
instance, struct nfs_inode has a fileid field that holds the 64-bit
inode number. With this set of changes, that field could be
eliminated. I'd rather leave that sort of cleanups for later just to
keep this simple"
* tag 'vfs-7.1-rc1.kino' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
nilfs2: fix 64-bit division operations in nilfs_bmap_find_target_in_group()
EVM: add comment describing why ino field is still unsigned long
vfs: remove externs from fs.h on functions modified by i_ino widening
treewide: fix missed i_ino format specifier conversions
ext4: fix signed format specifier in ext4_load_inode trace event
treewide: change inode->i_ino from unsigned long to u64
nilfs2: widen trace event i_ino fields to u64
f2fs: widen trace event i_ino fields to u64
ext4: widen trace event i_ino fields to u64
zonefs: widen trace event i_ino fields to u64
hugetlbfs: widen trace event i_ino fields to u64
ext2: widen trace event i_ino fields to u64
cachefiles: widen trace event i_ino fields to u64
vfs: widen trace event i_ino fields to u64
net: change sock.sk_ino and sock_i_ino() to u64
audit: widen ino fields to u64
vfs: widen inode hash/lookup functions to u64
In ext4_alloc_file_blocks(), pagecache_isize_extended() is called under
an active handle and may also hold folio lock if the block size is
smaller than the folio size. This also breaks the "folio lock ->
transaction start" lock ordering for the upcoming iomap buffered I/O
path.
Therefore, move pagecache_isize_extended() outside of an active handle.
Additionally, it is unnecessary to update the file length during each
iteration of the allocation loop. Instead, update the file length only
to the position where the allocation is successful. Postpone updating
the inode size until after the allocation loop completes or is
interrupted due to an error.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20260327102939.1095257-13-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
The ctime and mtime update is already handled by file_modified() in
ext4_fallocate(), the caller of ext4_alloc_file_blocks(). So remove the
redundant calls to inode_set_ctime_current() and inode_set_mtime_to_ts()
in ext4_alloc_file_blocks().
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20260327102939.1095257-12-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
In the ext4 fallocate call chain, SYNC mode handling is inconsistent:
some places check the inode state, while others check the open file
descriptor state. Unify these checks by evaluating both conditions
to ensure consistent behavior across all fallocate operations.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20260327102939.1095257-11-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
In ext4_zero_range() and ext4_punch_hole(), when operating in SYNC mode
and zeroing a partial block, only data=journal modes guarantee that the
zeroed data is synchronously persisted after the operation completes.
For data=ordered/writeback mode and non-journal modes, this guarantee is
missing.
Introduce a partial_zero parameter to explicitly trigger writeback for
all scenarios where a partial block is zeroed, ensuring the zeroed data
is durably persisted.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20260327102939.1095257-10-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Move ext4_block_zero_eof() and ext4_zero_partial_blocks() calls out of
the active handle context, making them independent operations, and also
add return value checks. This is safe because it still ensures data is
updated before metadata for data=ordered mode and data=journal mode
because we still zero data and ordering data before modifying the
metadata.
This change is required for iomap infrastructure conversion because the
iomap buffered I/O path does not use the same journal infrastructure for
partial block zeroing. The lock ordering of folio lock and starting
transactions is "folio lock -> transaction start", which is opposite of
the current path. Therefore, zeroing partial blocks cannot be performed
under the active handle.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20260327102939.1095257-9-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Change ext4_alloc_file_blocks() to accept offset and len in byte
granularity instead of block granularity. This allows callers to pass
byte offsets and lengths directly, and this prepares for moving the
ext4_zero_partial_blocks() call from the while(len) loop for unaligned
append writes, where it only needs to be invoked once before doing block
allocation.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20260327102939.1095257-8-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Only journal data mode requires an active journal handle when zeroing
partial blocks. Stop passing handle_t *handle to
ext4_zero_partial_blocks() and related functions, and make
ext4_block_journalled_zero_range() start a handle independently.
This change has no practical impact now because all callers invoke these
functions within the context of an active handle. It prepares for moving
ext4_block_zero_eof() out of an active handle in the next patch, which
is a prerequisite for converting block zero range operations to iomap
infrastructure.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20260327102939.1095257-7-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Rename ext4_block_truncate_page() to ext4_block_zero_eof() and extend
its signature to accept an explicit 'end' offset instead of calculating
the block boundary. This helper function now can replace all cases
requiring zeroing of the partial EOF block, including the append
buffered write paths in ext4_*_write_end().
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20260327102939.1095257-3-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
ext4_split_extent_at() retries after ext4_ext_insert_extent() fails by
refinding the original extent and restoring its length. That recovery is
only safe for transient resource failures such as -ENOSPC, -EDQUOT, and
-ENOMEM.
When ext4_ext_insert_extent() fails because the extent tree is already
corrupted, ext4_find_extent() can return a leaf path without p_ext.
ext4_split_extent_at() then dereferences path[depth].p_ext while trying to
fix up the original extent length, causing a NULL pointer dereference while
handling a pre-existing filesystem corruption.
Do not enter the recovery path for corruption errors, and validate p_ext
after refinding the extent before touching it. This keeps the recovery path
limited to cases it can actually repair and turns the syzbot-triggered crash
into a proper corruption report.
Fixes: 716b9c23b8 ("ext4: refactor split and convert extents")
Reported-by: syzbot+1ffa5d865557e51cb604@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=1ffa5d865557e51cb604
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: hongao <hongao@uniontech.com>
Link: https://patch.msgid.link/EF77870F23FF9C90+20260324015815.35248-1-hongao@uniontech.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Now, only EXT4_KUNIT_TESTS=Y testcase will be compiled in 'extents.c'.
To solve this issue, the ext4 test code needs to be decoupled. The
'extents-test' module is compiled into 'ext4-test' module.
Fixes: cb1e0c1d1f ("ext4: kunit tests for extent splitting and conversion")
Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20260314075258.1317579-4-yebin@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
On the mkdir/mknod path, when mapping logical blocks to physical blocks,
if inserting a new extent into the extent tree fails (in this example,
because the file system disabled the huge file feature when marking the
inode as dirty), ext4_ext_map_blocks() only calls ext4_free_blocks() to
reclaim the physical block without deleting the corresponding data in
the extent tree. This causes subsequent mkdir operations to reference
the previously reclaimed physical block number again, even though this
physical block is already being used by the xattr block. Therefore, a
situation arises where both the directory and xattr are using the same
buffer head block in memory simultaneously.
The above causes ext4_xattr_block_set() to enter an infinite loop about
"inserted" and cannot release the inode lock, ultimately leading to the
143s blocking problem mentioned in [1].
If the metadata is corrupted, then trying to remove some extent space
can do even more harm. Also in case EXT4_GET_BLOCKS_DELALLOC_RESERVE
was passed, remove space wrongly update quota information.
Jan Kara suggests distinguishing between two cases:
1) The error is ENOSPC or EDQUOT - in this case the filesystem is fully
consistent and we must maintain its consistency including all the
accounting. However these errors can happen only early before we've
inserted the extent into the extent tree. So current code works correctly
for this case.
2) Some other error - this means metadata is corrupted. We should strive to
do as few modifications as possible to limit damage. So I'd just skip
freeing of allocated blocks.
[1]
INFO: task syz.0.17:5995 blocked for more than 143 seconds.
Call Trace:
inode_lock_nested include/linux/fs.h:1073 [inline]
__start_dirop fs/namei.c:2923 [inline]
start_dirop fs/namei.c:2934 [inline]
Reported-by: syzbot+512459401510e2a9a39f@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=1659aaaaa8d9d11265d7
Tested-by: syzbot+1659aaaaa8d9d11265d7@syzkaller.appspotmail.com
Reported-by: syzbot+1659aaaaa8d9d11265d7@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=512459401510e2a9a39f
Tested-by: syzbot+1659aaaaa8d9d11265d7@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Tested-by: syzbot+512459401510e2a9a39f@syzkaller.appspotmail.com
Link: https://patch.msgid.link/tencent_43696283A68450B761D76866C6F360E36705@qq.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
ext4_ext_correct_indexes() walks up the extent tree correcting
index entries when the first extent in a leaf is modified. Before
accessing path[k].p_idx->ei_block, there is no validation that
p_idx falls within the valid range of index entries for that
level.
If the on-disk extent header contains a corrupted or crafted
eh_entries value, p_idx can point past the end of the allocated
buffer, causing a slab-out-of-bounds read.
Fix this by validating path[k].p_idx against EXT_LAST_INDEX() at
both access sites: before the while loop and inside it. Return
-EFSCORRUPTED if the index pointer is out of range, consistent
with how other bounds violations are handled in the ext4 extent
tree code.
Reported-by: syzbot+04c4e65cab786a2e5b7e@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=04c4e65cab786a2e5b7e
Signed-off-by: Tejas Bharambe <tejas.bharambe@outlook.com>
Link: https://patch.msgid.link/JH0PR06MB66326016F9B6AD24097D232B897CA@JH0PR06MB6632.apcprd06.prod.outlook.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
On 32-bit architectures, unsigned long is only 32 bits wide, which
causes 64-bit inode numbers to be silently truncated. Several
filesystems (NFS, XFS, BTRFS, etc.) can generate inode numbers that
exceed 32 bits, and this truncation can lead to inode number collisions
and other subtle bugs on 32-bit systems.
Change the type of inode->i_ino from unsigned long to u64 to ensure that
inode numbers are always represented as 64-bit values regardless of
architecture. Update all format specifiers treewide from %lu/%lx to
%llu/%llx to match the new type, along with corresponding local variable
types.
This is the bulk treewide conversion. Earlier patches in this series
handled trace events separately to allow trace field reordering for
better struct packing on 32-bit.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260304-iino-u64-v3-12-2257ad83d372@kernel.org
Acked-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:
Single allocations: kmalloc(sizeof(TYPE), ...)
are replaced with: kmalloc_obj(TYPE, ...)
Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with: kmalloc_objs(TYPE, COUNT, ...)
Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...)
(where TYPE may also be *VAR)
The resulting allocations no longer return "void *", instead returning
"TYPE *".
Signed-off-by: Kees Cook <kees@kernel.org>
Currently, when we are doing an extent split and convert operation of
written to unwritten extent (example, as done by ZERO_RANGE), we don't
allow the zeroout fallback in case the extent tree manipulation fails.
This is mostly because zeroout might take unsually long and the fact that
this code path is more tolerant to failures than endio.
Since we have zeroout machinery in place, we might as well use it hence
lift this restriction. To mitigate zeroout taking too long respect the
max zeroout limit here so that the operation finishes relatively fast.
Also, add kunit tests for this case.
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/1c3349020b8e098a63f293b84bc8a9b56011cef4.1769149131.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
ext4_split_convert_extents() has been historically prone to subtle
bugs and inconsistent behavior due to the way all the various flags
interact with the extent split and conversion process. For example,
callers like ext4_convert_unwritten_extents_endio() and
convert_initialized_extents() needed to open code extent conversion
despite passing CONVERT or CONVERT_UNWRITTEN flags because
ext4_split_convert_extents() wasn't performing the conversion.
Hence, refactor ext4_split_convert_extents() to clearly enforce the
semantics of each flag. The major changes here are:
* Clearly separate the split and convert process:
* ext4_split_extent() and ext4_split_extent_at() are now only
responsible to perform the split.
* ext4_split_convert_extents() is now responsible to perform extent
conversion after calling ext4_split_extent() for splitting.
* This helps get rid of all the MARK_UNWRIT* flags.
* Clearly enforce the semantics of flags passed to
ext4_split_convert_extents():
* EXT4_GET_BLOCKS_CONVERT: Will convert the split extent to written
* EXT4_GET_BLOCKS_CONVERT_UNWRITTEN: Will convert the split extent to
unwritten
* Modify all callers to enforce the above semantics.
* Use ext4_split_convert_extents() instead of ext4_split_extents()
in ext4_ext_convert_to_initialized() for uniformity.
* Now that ext4_split_convert_extents() is handling caching to es, we
dont need to do it in ext4_split_extent_zeroout().
* Cleanup all callers open coding the conversion logic. Further, modify
kuniy tests to pass flags based on the new semantics.
>From an end user point of view, we should not see any changes in
behavior of ext4.
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/2084a383d69ceefbaa293b8fcf725365eca0a349.1769149131.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Currently, zeroout is used as a fallback in case we fail to
split/convert extents in the "traditional" modify-the-extent-tree way.
This is essential to mitigate failures in critical paths like extent
splitting during endio. However, the logic is very messy and not easy to
follow. Further, the fragile use of various flags has made it prone to
errors.
Refactor zeroout out logic by moving it up to ext4_split_extents().
Further, zeroout correctly based on the type of conversion we want, ie:
- unwritten to written: Zeroout everything around the mapped range.
- written to unwritten: Zeroout only the mapped range.
Also, ext4_ext_convert_to_initialized() now passes
EXT4_GET_BLOCKS_CONVERT to make the intention clear.
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/e1b51dedeca7c0b1f702141d91edfe4230560e7b.1769149131.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Currently, callers like ext4_convert_unwritten_extents() pass
EXT4_EX_NOCACHE flag to avoid caching extents however this is not
respected by ext4_convert_unwritten_extents_endio(). Hence, modify it to
accept flags from the caller and to pass the flags on to other extent
manipulation functions it calls. This makes sure the NOCACHE flag is
respected throughout the code path.
Also, since the caller already passes METADATA_NOFAIL and CONVERT flags
we don't need to explicitly pass it anymore.
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/7c2139e0ad32c49c19b194f72219e15d613de284.1769149131.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Currently, ext4_zero_range passes EXT4_EX_NOCACHE flag to avoid caching
extents however this is not respected by convert_initialized_extent().
Hence, modify it to accept flags from the caller and to pass the flags
on to other extent manipulation functions it calls. This makes
sure the NOCACHE flag is respected throughout the code path.
Also, we no longer explicitly pass CONVERT_UNWRITTEN as the caller takes
care of this.
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/07008fbb14db727fddcaf4c30e2346c49f6c8fe0.1769149131.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Add support in Kunit tests to ensure that the extent status cache is
also in sync after the extent split and conversion operations.
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/5f9d2668feeb89a3f3e9d03dadab8c10cbea3741.1769149131.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Add multiple KUnit tests to test various permutations of extent
splitting and conversion.
We test the following cases:
1. Split of unwritten extent into 2 parts and convert 1 part to written
2. Split of unwritten extent into 3 parts and convert 1 part to written
3. Split of written extent into 2 parts and convert 1 part to unwritten
4. Split of written extent into 3 parts and convert 1 part to unwritten
5. Zeroout fallback for all the above cases except 3-4 because zeroout
is not supported for written to unwritten splits
The main function we test here is ext4_split_convert_extents().
Currently some of the tests are failing due to issues in implementation.
All failures are mitigated at other layers in ext4 [1] but still point
out the mismatch in expectation of what the caller wants vs what the
function does.
The aim is to eventually fix all the failures we see here. More detailed
implementation notes can be found in the topmost commit in the test
file.
[1] for example, EXT4_GET_BLOCKS_CONVERT doesn't really convert the
split extent to written, but rather the callers end up doing the
conversion.
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/22bb9d17cd88c1318a2edde48887ca7488cb8a13.1769149131.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
We do not use EXT4_GET_BLOCKS_IO_CREATE_EXT or split extents before
submitting I/O; therefore, remove the related code.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/20260105014522.1937690-8-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Currently, when writing back dirty pages to the filesystem with the
dioread_nolock feature enabled and when doing DIO, if the area to be
written back is part of an unwritten extent, the
EXT4_GET_BLOCKS_IO_CREATE_EXT flag is set during block allocation before
submitting I/O. The function ext4_split_convert_extents() then attempts
to split this extent in advance. This approach is designed to prevents
extent splitting and conversion to the written type from failing due to
insufficient disk space at the time of I/O completion, which could
otherwise result in data loss.
However, we already have two mechanisms to ensure successful extent
conversion. The first is the EXT4_GET_BLOCKS_METADATA_NOFAIL flag, which
is a best effort, it permits the use of 2% of the reserved space or
4,096 blocks in the file system when splitting extents. This flag covers
most scenarios where extent splitting might fail. The second is the
EXT4_EXT_MAY_ZEROOUT flag, which is also set during extent splitting. If
the reserved space is insufficient and splitting fails, it does not
retry the allocation. Instead, it directly zeros out the extra part of
the extent, thereby avoiding splitting and directly converting the
entire extent to the written type.
These two mechanisms also exist when I/Os are completed because there is
a concurrency window between write-back and fallocate, which may still
require us to split extents upon I/O completion. There is no much
difference between splitting extents before submitting I/O. Therefore,
It seems possible to defer the splitting until I/O completion, it won't
increase the risk of I/O failure and data loss. On the contrary, if some
I/Os can be merged when I/O completion, it can also reduce unnecessary
splitting operations, thereby alleviating the pressure on reserved
space.
In addition, deferring extent splitting until I/O completion can
also simplify the IO submission process and avoid initiating unnecessary
journal handles when writing unwritten extents.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/20260105014522.1937690-3-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
When performing buffered writes, we may need to split and convert an
unwritten extent into a written one during the end I/O process. However,
we do not reserve space specifically for these metadata changes, we only
reserve 2% of space or 4096 blocks. To address this, we use
EXT4_GET_BLOCKS_PRE_IO to potentially split extents in advance and
EXT4_GET_BLOCKS_METADATA_NOFAIL to utilize reserved space if necessary.
These two approaches can reduce the likelihood of running out of space
and losing data. However, these methods are merely best efforts, we
could still run out of space, and there is not much difference between
converting an extent during the writeback process and the end I/O
process, it won't increase the risk of losing data if we postpone the
conversion.
Therefore, also use EXT4_GET_BLOCKS_METADATA_NOFAIL in
ext4_convert_unwritten_extents_endio() to prepare for the buffered I/O
iomap conversion, which may perform extent conversion during the end I/O
process.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/20260105014522.1937690-2-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
In ext4_ext_shift_extents(), if the extent is NULL in the while loop, the
function returns immediately without releasing the path obtained via
ext4_find_extent(), leading to a memory leak.
Fix this by jumping to the out label to ensure the path is properly
released.
Fixes: a18ed359bd ("ext4: always check ext4_ext_find_extent result")
Signed-off-by: Zilin Guan <zilin@seu.edu.cn>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Link: https://patch.msgid.link/20251225084800.905701-1-zilin@seu.edu.cn
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
In ext4, the remaining places for inserting extents into the extent
status tree within ext4_ext_determine_insert_hole() and
ext4_map_query_blocks() directly cache on-disk extents. We can use
ext4_es_cache_extent() instead of ext4_es_insert_extent() in these
cases. This will help reduce unnecessary increases in extent sequence
numbers and cache invalidations after supporting IOMAP in the future.
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Message-ID: <20251129103247.686136-14-yi.zhang@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
zero_ex is a temporary variable used only for writing zeros and
inserting extent status entry, it will not be directly inserted into the
tree. Therefore, it can be assigned values from the target extent in
various scenarios, eliminating the need to explicitly assign values to
each variable individually.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Message-ID: <20251129103247.686136-9-yi.zhang@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
When the split extent fails, we might leave some extents still being
processed and return an error directly, which will result in stale
extent entries remaining in the extent status tree. So drop all of the
remaining potentially stale extents if the splitting fails.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Cc: stable@kernel.org
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Message-ID: <20251129103247.686136-8-yi.zhang@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
When splitting an unwritten extent in the middle and converting it to
initialized in ext4_split_extent() with the EXT4_EXT_MAY_ZEROOUT and
EXT4_EXT_DATA_VALID2 flags set, it could leave a stale unwritten extent.
Assume we have an unwritten file and buffered write in the middle of it
without dioread_nolock enabled, it will allocate blocks as written
extent.
0 A B N
[UUUUUUUUUUUU] on-disk extent U: unwritten extent
[UUUUUUUUUUUU] extent status tree
[--DDDDDDDD--] D: valid data
|<- ->| ----> this range needs to be initialized
ext4_split_extent() first try to split this extent at B with
EXT4_EXT_DATA_PARTIAL_VALID1 and EXT4_EXT_MAY_ZEROOUT flag set, but
ext4_split_extent_at() failed to split this extent due to temporary lack
of space. It zeroout B to N and leave the entire extent as unwritten.
0 A B N
[UUUUUUUUUUUU] on-disk extent
[UUUUUUUUUUUU] extent status tree
[--DDDDDDDDZZ] Z: zeroed data
ext4_split_extent() then try to split this extent at A with
EXT4_EXT_DATA_VALID2 flag set. This time, it split successfully and
leave an written extent from A to N.
0 A B N
[UUWWWWWWWWWW] on-disk extent W: written extent
[UUUUUUUUUUUU] extent status tree
[--DDDDDDDDZZ]
Finally ext4_map_create_blocks() only insert extent A to B to the extent
status tree, and leave an stale unwritten extent in the status tree.
0 A B N
[UUWWWWWWWWWW] on-disk extent W: written extent
[UUWWWWWWWWUU] extent status tree
[--DDDDDDDDZZ]
Fix this issue by always cached extent status entry after zeroing out
the second part.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Cc: stable@kernel.org
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Message-ID: <20251129103247.686136-7-yi.zhang@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Caching extents during the splitting process is risky, as it may result
in stale extents remaining in the status tree. Moreover, in most cases,
the corresponding extent block entries are likely already cached before
the split happens, making caching here not particularly useful.
Assume we have an unwritten extent, and then DIO writes the first half.
[UUUUUUUUUUUUUUUU] on-disk extent U: unwritten extent
[UUUUUUUUUUUUUUUU] extent status tree
|<- ->| ----> dio write this range
First, when ext4_split_extent_at() splits this extent, it truncates the
existing extent and then inserts a new one. During this process, this
extent status entry may be shrunk, and calls to ext4_find_extent() and
ext4_cache_extents() may occur, which could potentially insert the
truncated range as a hole into the extent status tree. After the split
is completed, this hole is not replaced with the correct status.
[UUUUUUU|UUUUUUUU] on-disk extent U: unwritten extent
[UUUUUUU|HHHHHHHH] extent status tree H: hole
Then, the outer calling functions will not correct this remaining hole
extent either. Finally, if we perform a delayed buffer write on this
latter part, it will re-insert the delayed extent and cause an error in
space accounting.
In adition, if the unwritten extent cache is not shrunk during the
splitting, ext4_cache_extents() also conflicts with existing extents
when caching extents. In the future, we will add checks when caching
extents, which will trigger a warning. Therefore, Do not cache extents
that are being split.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Cc: stable@kernel.org
Message-ID: <20251129103247.686136-6-yi.zhang@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Before submitting I/O and allocating blocks with the
EXT4_GET_BLOCKS_PRE_IO flag set, ext4_split_convert_extents() may
convert the target extent range to initialized due to ENOSPC, ENOMEM, or
EQUOTA errors. However, it still marks the mapping as incorrectly
unwritten. Although this may not seem to cause any practical problems,
it will result in an unnecessary extent conversion operation after I/O
completion. Therefore, it's better to correct the returned mapping
status.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Message-ID: <20251129103247.686136-5-yi.zhang@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
When allocating blocks during within-EOF DIO and writeback with
dioread_nolock enabled, EXT4_GET_BLOCKS_PRE_IO was set to split an
existing large unwritten extent. However, EXT4_GET_BLOCKS_CONVERT was
set when calling ext4_split_convert_extents(), which may potentially
result in stale data issues.
Assume we have an unwritten extent, and then DIO writes the second half.
[UUUUUUUUUUUUUUUU] on-disk extent U: unwritten extent
[UUUUUUUUUUUUUUUU] extent status tree
|<- ->| ----> dio write this range
First, ext4_iomap_alloc() call ext4_map_blocks() with
EXT4_GET_BLOCKS_PRE_IO, EXT4_GET_BLOCKS_UNWRIT_EXT and
EXT4_GET_BLOCKS_CREATE flags set. ext4_map_blocks() find this extent and
call ext4_split_convert_extents() with EXT4_GET_BLOCKS_CONVERT and the
above flags set.
Then, ext4_split_convert_extents() calls ext4_split_extent() with
EXT4_EXT_MAY_ZEROOUT, EXT4_EXT_MARK_UNWRIT2 and EXT4_EXT_DATA_VALID2
flags set, and it calls ext4_split_extent_at() to split the second half
with EXT4_EXT_DATA_VALID2, EXT4_EXT_MARK_UNWRIT1, EXT4_EXT_MAY_ZEROOUT
and EXT4_EXT_MARK_UNWRIT2 flags set. However, ext4_split_extent_at()
failed to insert extent since a temporary lack -ENOSPC. It zeroes out
the first half but convert the entire on-disk extent to written since
the EXT4_EXT_DATA_VALID2 flag set, but left the second half as unwritten
in the extent status tree.
[0000000000SSSSSS] data S: stale data, 0: zeroed
[WWWWWWWWWWWWWWWW] on-disk extent W: written extent
[WWWWWWWWWWUUUUUU] extent status tree
Finally, if the DIO failed to write data to the disk, the stale data in
the second half will be exposed once the cached extent entry is gone.
Fix this issue by not passing EXT4_GET_BLOCKS_CONVERT when splitting
an unwritten extent before submitting I/O, and make
ext4_split_convert_extents() to zero out the entire extent range
to zero for this case, and also mark the extent in the extent status
tree for consistency.
Fixes: b8a8684502 ("ext4: Introduce FALLOC_FL_ZERO_RANGE flag for fallocate")
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Cc: stable@kernel.org
Message-ID: <20251129103247.686136-4-yi.zhang@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
When allocating initialized blocks from a large unwritten extent, or
when splitting an unwritten extent during end I/O and converting it to
initialized, there is currently a potential issue of stale data if the
extent needs to be split in the middle.
0 A B N
[UUUUUUUUUUUU] U: unwritten extent
[--DDDDDDDD--] D: valid data
|<- ->| ----> this range needs to be initialized
ext4_split_extent() first try to split this extent at B with
EXT4_EXT_DATA_ENTIRE_VALID1 and EXT4_EXT_MAY_ZEROOUT flag set, but
ext4_split_extent_at() failed to split this extent due to temporary lack
of space. It zeroout B to N and mark the entire extent from 0 to N
as written.
0 A B N
[WWWWWWWWWWWW] W: written extent
[SSDDDDDDDDZZ] Z: zeroed, S: stale data
ext4_split_extent() then try to split this extent at A with
EXT4_EXT_DATA_VALID2 flag set. This time, it split successfully and left
a stale written extent from 0 to A.
0 A B N
[WW|WWWWWWWWWW]
[SS|DDDDDDDDZZ]
Fix this by pass EXT4_EXT_DATA_PARTIAL_VALID1 to ext4_split_extent_at()
when splitting at B, don't convert the entire extent to written and left
it as unwritten after zeroing out B to N. The remaining work is just
like the standard two-part split. ext4_split_extent() will pass the
EXT4_EXT_DATA_VALID2 flag when it calls ext4_split_extent_at() for the
second time, allowing it to properly handle the split. If the split is
successful, it will keep extent from 0 to A as unwritten.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Cc: stable@kernel.org
Message-ID: <20251129103247.686136-3-yi.zhang@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
When splitting an extent, if the EXT4_GET_BLOCKS_CONVERT flag is set and
it is necessary to split the target extent in the middle,
ext4_split_extent() first handles splitting the latter half of the
extent and passes the EXT4_EXT_DATA_VALID1 flag. This flag implies that
all blocks before the split point contain valid data; however, this
assumption is incorrect.
Therefore, subdivid EXT4_EXT_DATA_VALID1 into
EXT4_EXT_DATA_ENTIRE_VALID1 and EXT4_EXT_DATA_PARTIAL_VALID1, which
indicate that the first half of the extent is either entirely valid or
only partially valid, respectively. These two flags cannot be set
simultaneously.
This patch does not use EXT4_EXT_DATA_PARTIAL_VALID1, it only replaces
EXT4_EXT_DATA_VALID1 with EXT4_EXT_DATA_ENTIRE_VALID1 at the location
where it is set, no logical changes.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Cc: stable@kernel.org
Message-ID: <20251129103247.686136-2-yi.zhang@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
No functional changes.
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Message-ID: <20251121090654.631996-10-libaokun@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Move the comments just before we set EXT4_EXT_MAY_ZEROOUT in
ext4_split_convert_extents.
Signed-off-by: Yang Erkun <yangerkun@huawei.com>
Message-ID: <20251112084538.1658232-4-yangerkun@huawei.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This flag has been generalized to split an unwritten extent when we do
dio or dioread_nolock writeback, or to avoid merge new extents which was
created by extents split. Update some related comments too.
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Signed-off-by: Yang Erkun <yangerkun@huawei.com>
Message-ID: <20251112084538.1658232-2-yangerkun@huawei.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
When querying extents in the extent status tree, we should hold the
data_sem if we want to obtain the sequence number as a valid cookie
simultaneously. However, currently, ext4_map_blocks() calls
ext4_es_lookup_extent() without holding data_sem. Therefore, we should
acquire i_es_lock instead, which also ensures that the sequence cookie
and the extent remain consistent. Consequently, make
ext4_es_lookup_extent() to pass out the sequence number when necessary.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Message-ID: <20251013015128.499308-4-yi.zhang@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
- Better scalability for ext4 block allocation
- Fix insufficient credits when writing back large folios
Miscellaneous bug fixes, especially when handling exteded attriutes,
inline data, and fast commit.
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Merge tag 'ext4_for_linus_6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
Pull ext4 updates from Ted Ts'o:
"Major ext4 changes for 6.17:
- Better scalability for ext4 block allocation
- Fix insufficient credits when writing back large folios
Miscellaneous bug fixes, especially when handling exteded attriutes,
inline data, and fast commit"
* tag 'ext4_for_linus_6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (39 commits)
ext4: do not BUG when INLINE_DATA_FL lacks system.data xattr
ext4: implement linear-like traversal across order xarrays
ext4: refactor choose group to scan group
ext4: convert free groups order lists to xarrays
ext4: factor out ext4_mb_scan_group()
ext4: factor out ext4_mb_might_prefetch()
ext4: factor out __ext4_mb_scan_group()
ext4: fix largest free orders lists corruption on mb_optimize_scan switch
ext4: fix zombie groups in average fragment size lists
ext4: merge freed extent with existing extents before insertion
ext4: convert sbi->s_mb_free_pending to atomic_t
ext4: fix typo in CR_GOAL_LEN_SLOW comment
ext4: get rid of some obsolete EXT4_MB_HINT flags
ext4: utilize multiple global goals to reduce contention
ext4: remove unnecessary s_md_lock on update s_mb_last_group
ext4: remove unnecessary s_mb_last_start
ext4: separate stream goal hits from s_bal_goals for better tracking
ext4: add ext4_try_lock_group() to skip busy groups
ext4: initialize superblock fields in the kballoc-test.c kunit tests
ext4: refactor the inline directory conversion and new directory codepaths
...
After ext4 supports large folios, the semantics of reserving credits in
pages is no longer applicable. In most scenarios, reserving credits in
extents is sufficient. Therefore, introduce ext4_chunk_trans_extent()
to replace ext4_writepage_trans_blocks(). move_extent_per_page() is the
only remaining location where we are still processing extents in pages.
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20250707140814.542883-10-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Add support for FALLOC_FL_WRITE_ZEROES if the underlying device enable
the unmap write zeroes operation. This first allocates blocks as
unwritten, then issues a zero command outside of the running journal
handle, and finally converts them to a written state.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://lore.kernel.org/20250619111806.3546162-10-yi.zhang@huaweicloud.com
Reviewed-by: "Martin K. Petersen" <martin.petersen@oracle.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
We added the documentation in ext4_map_blocks() for usage of
EXT4_GET_BLOCKS_QUERY_LAST_IN_LEAF flag. But It's better to add
a WARN_ON_ONCE in case if anyone tries using this flag with CREATE to
avoid a random issue later. Since depth can change with CREATE and it
needs to be re-calculated before using it in there.
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/ee6e82a224c50b432df9ce1ce3333c50182d8473.1747677758.git.ritesh.list@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This fixes the atomic write patch series after it was rebased on top of
extent status cache cleanup series i.e.
'commit 402e38e6b7 ("ext4: prevent stale extent cache entries caused by
concurrent I/O writeback")'
After the above series, EXT4_GET_BLOCKS_IO_CONVERT_EXT flag which has
EXT4_GET_BLOCKS_IO_SUBMIT flag set, requires that the io submit context
of any kind should pass EXT4_EX_NOCACHE to avoid caching unncecessary
extents in the extent status cache.
This patch fixes that by adding the EXT4_EX_NOCACHE flag in
ext4_convert_unwritten_extents_atomic() for unwritten to written
conversion calls to ext4_map_blocks().
Fixes: b86629c2b2 ("ext4: Add multi-fsblock atomic write support with bigalloc")
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/ea0ad9378ff6d31d73f4e53f87548e3a20817689.1747677758.git.ritesh.list@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
EXT4 supports bigalloc feature which allows the FS to work in size of
clusters (group of blocks) rather than individual blocks. This patch
adds atomic write support for bigalloc so that systems with bs = ps can
also create FS using -
mkfs.ext4 -F -O bigalloc -b 4096 -C 16384 <dev>
With bigalloc ext4 can support multi-fsblock atomic writes. We will have to
adjust ext4's atomic write unit max value to cluster size. This can then support
atomic write of size anywhere between [blocksize, clustersize]. This
patch adds the required changes to enable multi-fsblock atomic write
support using bigalloc in the next patch.
In this patch for block allocation:
we first query the underlying region of the requested range by calling
ext4_map_blocks() call. Here are the various cases which we then handle
depending upon the underlying mapping type:
1. If the underlying region for the entire requested range is a mapped extent,
then we don't call ext4_map_blocks() to allocate anything. We don't need to
even start the jbd2 txn in this case.
2. For an append write case, we create a mapped extent.
3. If the underlying region is entirely a hole, then we create an unwritten
extent for the requested range.
4. If the underlying region is a large unwritten extent, then we split the
extent into 2 unwritten extent of required size.
5. If the underlying region has any type of mixed mapping, then we call
ext4_map_blocks() in a loop to zero out the unwritten and the hole regions
within the requested range. This then provide a single mapped extent type
mapping for the requested range.
Note: We invoke ext4_map_blocks() in a loop with the EXT4_GET_BLOCKS_ZERO
flag only when the underlying extent mapping of the requested range is
not entirely a hole, an unwritten extent, or a fully mapped extent. That
is, if the underlying region contains a mix of hole(s), unwritten
extent(s), and mapped extent(s), we use this loop to ensure that all the
short mappings are zeroed out. This guarantees that the entire requested
range becomes a single, uniformly mapped extent. It is ok to do so
because we know this is being done on a bigalloc enabled filesystem
where the block bitmap represents the entire cluster unit.
Note having a single contiguous underlying region of type mapped,
unwrittn or hole is not a problem. But the reason to avoid writing on
top of mixed mapping region is because, atomic writes requires all or
nothing should get written for the userspace pwritev2 request. So if at
any point in time during the write if a crash or a sudden poweroff
occurs, the region undergoing atomic write should read either complete
old data or complete new data. But it should never have a mix of both
old and new data.
So, we first convert any mixed mapping region to a single contiguous
mapped extent before any data gets written to it. This is because
normally FS will only convert unwritten extents to written at the end of
the write in ->end_io() call. And if we allow the writes over a mixed
mapping and if a sudden power off happens in between, we will end up
reading mix of new data (over mapped extents) and old data (over
unwritten extents), because unwritten to written conversion never went
through.
So to avoid this and to avoid writes getting torned due to mixed
mapping, we first allocate a single contiguous block mapping and then
do the write.
Acked-by: Darrick J. Wong <djwong@kernel.org>
Co-developed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://patch.msgid.link/c4965ac3407cbc773f0bc954d0966d9696f5038a.1747337952.git.ritesh.list@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
There can be a case where there are contiguous extents on the adjacent
leaf nodes of on-disk extent trees. So when someone tries to write to
this contiguous range, ext4_map_blocks() call will split by returning
1 extent at a time if this is not already cached in extent_status tree
cache (where if these extents when cached can get merged since they are
contiguous).
This is fine for a normal write however in case of atomic writes, it
can't afford to break the write into two. Now this is also something
that will only happen in the slow write case where we call
ext4_map_blocks() for each of these extents spread across different leaf
nodes. However, there is no guarantee that these extent status cache
cannot be reclaimed before the last call to ext4_map_blocks() in
ext4_map_blocks_atomic_write_slow().
Hence this patch adds support of EXT4_GET_BLOCKS_QUERY_LEAF_BLOCKS.
This flag checks if the requested range can be fully found in extent
status cache and return. If not, it looks up in on-disk extent
tree via ext4_map_query_blocks(). If the found extent is the last entry
in the leaf node, then it goes and queries the next lblk to see if there
is an adjacent contiguous extent in the adjacent leaf node of the
on-disk extent tree.
Even though there can be a case where there are multiple adjacent extent
entries spread across multiple leaf nodes. But we only read an adjacent
leaf block i.e. in total of 2 extent entries spread across 2 leaf nodes.
The reason for this is that we are mostly only going to support atomic
writes with upto 64KB or maybe max upto 1MB of atomic write support.
Acked-by: Darrick J. Wong <djwong@kernel.org>
Co-developed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://patch.msgid.link/6bb563e661f5fbd80e266a9e6ce6e29178f555f6.1747337952.git.ritesh.list@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Since ext4_chksum() no longer uses its sbi argument, remove it.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Link: https://patch.msgid.link/20250513053809.699974-2-ebiggers@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
