kernel/fs/ext4/ext4.h, branch linux-rolling-stable

ext4: fast commit: make s_fc_lock reclaim-safe

2026-02-26T23:01:06Z

[ Upstream commit 491f2927ae097e2d405afe0b3fe841931ab8aad2 ] s_fc_lock can be acquired from inode eviction and thus is reclaim unsafe. Since the fast commit path holds s_fc_lock while writing the commit log, allocations under the lock can enter reclaim and invert the lock order with fs_reclaim. Add ext4_fc_lock()/ext4_fc_unlock() helpers which acquire s_fc_lock under memalloc_nofs_save()/restore() context and use them everywhere so allocations under the lock cannot recurse into filesystem reclaim. Fixes: 6593714d67ba ("ext4: hold s_fc_lock while during fast commit") Signed-off-by: Li Chen Reviewed-by: Baokun Li Reviewed-by: Zhang Yi Reviewed-by: Jan Kara Link: https://patch.msgid.link/20260106120621.440126-1-me@linux.beauty Signed-off-by: Theodore Ts'o Signed-off-by: Sasha Levin

ext4: add checks for large folio incompatibilities when BS > PS

2025-11-29T03:35:28Z

Supporting a block size greater than the page size (BS > PS) requires support for large folios. However, several features (e.g., encrypt) do not yet support large folios. To prevent conflicts, this patch adds checks at mount time to prohibit these features from being used when BS > PS. Since these features cannot be changed on remount, there is no need to check on remount. This patch adds s_max_folio_order, initialized during mount according to filesystem features and mount options. If s_max_folio_order is 0, large folios are disabled. With this in place, ext4_set_inode_mapping_order() can be simplified by checking s_max_folio_order, avoiding redundant checks. Signed-off-by: Baokun Li Reviewed-by: Jan Kara Reviewed-by: Zhang Yi Reviewed-by: Ojaswin Mujoo Message-ID: <20251121090654.631996-24-libaokun@huaweicloud.com> Signed-off-by: Theodore Ts'o

ext4: add EXT4_LBLK_TO_PG and EXT4_PG_TO_LBLK for block/page conversion

2025-11-29T03:35:27Z

As BS > PS support is coming, all block number to page index (and vice-versa) conversions must now go via bytes. Added EXT4_LBLK_TO_PG() and EXT4_PG_TO_LBLK() macros to simplify these conversions and handle both BS <= PS and BS > PS scenarios cleanly. Suggested-by: Jan Kara Signed-off-by: Baokun Li Reviewed-by: Zhang Yi Reviewed-by: Jan Kara Reviewed-by: Ojaswin Mujoo Message-ID: <20251121090654.631996-11-libaokun@huaweicloud.com> Signed-off-by: Theodore Ts'o

ext4: add EXT4_LBLK_TO_B macro for logical block to bytes conversion

2025-11-29T03:35:27Z

No functional changes. Signed-off-by: Baokun Li Reviewed-by: Zhang Yi Reviewed-by: Jan Kara Reviewed-by: Ojaswin Mujoo Message-ID: <20251121090654.631996-10-libaokun@huaweicloud.com> Signed-off-by: Theodore Ts'o

ext4: introduce s_min_folio_order for future BS > PS support

2025-11-29T03:35:26Z

This commit introduces the s_min_folio_order field to the ext4_sb_info structure. This field will store the minimum folio order required by the current filesystem, laying groundwork for future support of block sizes greater than PAGE_SIZE. Signed-off-by: Baokun Li Reviewed-by: Zhang Yi Reviewed-by: Jan Kara Reviewed-by: Pankaj Raghav Reviewed-by: Ojaswin Mujoo Message-ID: <20251121090654.631996-7-libaokun@huaweicloud.com> Signed-off-by: Theodore Ts'o

ext4: remove PAGE_SIZE checks for rec_len conversion

2025-11-29T03:35:26Z

Previously, ext4_rec_len_(to|from)_disk only performed complex rec_len conversions when PAGE_SIZE >= 65536 to reduce complexity. However, we are soon to support file system block sizes greater than page size, which makes these conditional checks unnecessary. Thus, these checks are now removed. Signed-off-by: Baokun Li Reviewed-by: Zhang Yi Reviewed-by: Jan Kara Reviewed-by: Ojaswin Mujoo Message-ID: <20251121090654.631996-4-libaokun@huaweicloud.com> Signed-off-by: Theodore Ts'o

ext4: rename EXT4_GET_BLOCKS_PRE_IO

2025-11-26T22:13:33Z

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 Reviewed-by: Jan Kara Reviewed-by: Baokun Li Signed-off-by: Yang Erkun Message-ID: <20251112084538.1658232-2-yangerkun@huawei.com> Signed-off-by: Theodore Ts'o

ext4: pass out extent seq counter when mapping blocks

2025-11-06T15:44:39Z

When creating or querying mapping blocks using the ext4_map_blocks() and ext4_map_{query|create}_blocks() helpers, also pass out the extent sequence number of the block mapping info through the ext4_map_blocks structure. This sequence number can later serve as a valid cookie within iomap infrastructure and the move extents procedure. Signed-off-by: Zhang Yi Reviewed-by: Jan Kara Message-ID: <20251013015128.499308-5-yi.zhang@huaweicloud.com> Signed-off-by: Theodore Ts'o

ext4: introduce seq counter for the extent status entry

2025-11-06T15:44:39Z

In the iomap_write_iter(), the iomap buffered write frame does not hold any locks between querying the inode extent mapping info and performing page cache writes. As a result, the extent mapping can be changed due to concurrent I/O in flight. Similarly, in the iomap_writepage_map(), the write-back process faces a similar problem: concurrent changes can invalidate the extent mapping before the I/O is submitted. Therefore, both of these processes must recheck the mapping info after acquiring the folio lock. To address this, similar to XFS, we propose introducing an extent sequence number to serve as a validity cookie for the extent. After commit 24b7a2331fcd ("ext4: clairfy the rules for modifying extents"), we can ensure the extent information should always be processed through the extent status tree, and the extent status tree is always uptodate under i_rwsem or invalidate_lock or folio lock, so it's safe to introduce this sequence number. The sequence number will be increased whenever the extent status tree changes, preparing for the buffered write iomap conversion. Besides, this mechanism is also applicable for the moving extents case. In move_extent_per_page(), it also needs to reacquire data_sem and check the mapping info again under the folio lock. Signed-off-by: Zhang Yi Reviewed-by: Jan Kara Message-ID: <20251013015128.499308-3-yi.zhang@huaweicloud.com> Signed-off-by: Theodore Ts'o

Merge tag 'ext4_for_linus-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

2025-10-03T20:47:10Z

Pull ext4 updates from Ted Ts'o: "New ext4 features: - Add support so tune2fs can modify/update the superblock using an ioctl, without needing write access to the block device - Add support for 32-bit reserved uid's and gid's Bug fixes: - Fix potential warnings and other failures caused by corrupted / fuzzed file systems - Fail unaligned direct I/O write with EINVAL instead of silently falling back to buffered I/O - Correectly handle fsmap queries for metadata mappings - Avoid journal stalls caused by writeback throttling - Add some missing GFP_NOFAIL flags to avoid potential deadlocks under extremem memory pressure Cleanups: - Remove obsolete EXT3 Kconfigs" * tag 'ext4_for_linus-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: ext4: fix checks for orphan inodes ext4: validate ea_ino and size in check_xattrs ext4: guard against EA inode refcount underflow in xattr update ext4: implemet new ioctls to set and get superblock parameters ext4: add support for 32-bit default reserved uid and gid values ext4: avoid potential buffer over-read in parse_apply_sb_mount_options() ext4: fix an off-by-one issue during moving extents ext4: increase i_disksize to offset + len in ext4_update_disksize_before_punch() ext4: verify orphan file size is not too big ext4: fail unaligned direct IO write with EINVAL ext4: correctly handle queries for metadata mappings ext4: increase IO priority of fastcommit ext4: remove obsolete EXT3 config options jbd2: increase IO priority of checkpoint ext4: fix potential null deref in ext4_mb_init() ext4: add ext4_sb_bread_nofail() helper function for ext4_free_branches() ext4: replace min/max nesting with clamp() fs: ext4: change GFP_KERNEL to GFP_NOFS to avoid deadlock