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authorDonggeun Yoo <donggeunyoo.kernel@gmail.com>2026-09-02 00:21:26 +0900
committerJonathan Cameron <jonathan.cameron@oss.qualcomm.com>2026-09-07 02:24:53 +0100
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tree43a2533acc955d11f5cb8be1ecba0ab8ba4cbb1e /Documentation/filesystems/ext4/overview.rst
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iio: proximity: vl53l0x-i2c: claim direct mode for raw readsgrafted
vl53l0x_read_raw() starts a single-shot ranging measurement and reads back the result. Once the triggered buffer is enabled the sensor runs in continuous mode and its data-ready interrupt is routed to the trigger, so a concurrent in_distance_raw read disturbs the streaming setup and never gets its completion, returning -ETIMEDOUT. The original submission claimed direct mode here, but it was dropped during review because the driver had no buffer support at the time [1]. Continuous (buffered) mode was later added without restoring the claim [2], reintroducing the conflict. Reject direct reads while buffered capture is active by claiming direct mode around the measurement, as the vl53l1x sibling already does. Fixes: 762186c6e7b1 ("iio: proximity: vl53l0x-i2c: Added continuous mode support") Link: https://lore.kernel.org/linux-iio/20180911160300.GA9212@himanshu-Vostro-3559/ [1] Link: https://lore.kernel.org/linux-iio/20240909101508.263085-3-abhashkumarjha123@gmail.com/ [2] Signed-off-by: Donggeun Yoo <donggeunyoo.kernel@gmail.com> Cc: stable@vger.kernel.org Signed-off-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>
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+.. SPDX-License-Identifier: GPL-2.0
+
+High Level Design
+=================
+
+An ext4 file system is split into a series of block groups. To reduce
+performance difficulties due to fragmentation, the block allocator tries
+very hard to keep each file's blocks within the same group, thereby
+reducing seek times. The size of a block group is specified in
+``sb.s_blocks_per_group`` blocks, though it can also calculated as 8 *
+``block_size_in_bytes``. With the default block size of 4KiB, each group
+will contain 32,768 blocks, for a length of 128MiB. The number of block
+groups is the size of the device divided by the size of a block group.
+
+All fields in ext4 are written to disk in little-endian order. HOWEVER,
+all fields in jbd2 (the journal) are written to disk in big-endian
+order.
+
+.. toctree::
+
+ blocks
+ blockgroup
+ special_inodes
+ allocators
+ checksums
+ bigalloc
+ inlinedata
+ eainode
+ verity
+ atomic_writes