[PATCH v2 0/1] exfat: reduce directory scans during file creation

[Yang Wen]

Creating files in a large exfat directory may require repeated linear
directory scans.

After an empty-entry hint is used successfully, the remaining
contiguous empty entries are not retained for the next create operation.
This can cause subsequent operations to rediscover available directory
space.

In a test creating 20,000 files with random names and sizes between 1 KiB
and 4 KiB in one directory, the elapsed time changed as follows:

  Before: 3879 seconds
  After:  3050 seconds

---

Changes since v1:
- Drop the LOOKUP_CREATE negative dentry change.
- Make exfat_cache_next_empty_entry() return void and skip caching if
  exfat_chain_advance() fails.

Yang Wen (1):
  exfat: preserve the next empty-entry hint after allocation

 fs/exfat/namei.c | 39 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 37 insertions(+), 2 deletions(-)

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2.34.1