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Authored by haltode on Oct 27 2020, 10:07 AM.

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	[Question] getdents() calls use very small buffer when FUSE mount

	Hello all!

	I am currently working on a FUSE filesystem where a directory can
	contain a large amount of entries. When running `strace ls` I can see a
	lot of calls to getdents64() but with very small buffer:

	getdents64(3, /* 19 entries */, 32768) = 1368
	getdents64(3, /* 19 entries */, 32768) = 1368
	getdents64(3, /* 19 entries */, 32768) = 1368
	getdents64(3, /* 19 entries */, 32768) = 1368
	getdents64(3, /* 19 entries */, 32768) = 1368
	getdents64(3, /* 19 entries */, 32768) = 1368
	getdents64(3, /* 19 entries */, 32768) = 1368
	...

	This is completely killing the performances of the filesystem and I was
	wondering what causes such buffer size limitation? I stumbled upon a few
	posts, like this one:
	https://bugzilla.redhat.com/show_bug.cgi?id=1478411 about the same kind
	of problem, however I am not sure whether there is still a pending patch
	somewhere or a particular option to set in order to fix this issue?

	My system is:

	- Debian GNU/Linux bullseye/sid (testing)
	- Linux kernel 5.8.0-2-amd64 (x86-64)
	- libfuse 3.10.0

	Thanks in advance for your insights.
	Sincerely,

haltode created this object in space S1 Public.

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