docs/fuse-io: Document the usage of DIRECT_IO_ALLOW_MMAP

By default, shared mmap is disabled in FUSE DIRECT_IO mode. However,
when the DIRECT_IO_ALLOW_MMAP flag is enabled in the FUSE_INIT reply,
shared mmap is allowed.

Signed-off-by: Tyler Fanelli <tfanelli@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Tyler Fanelli 2023-09-19 22:40:01 -04:00 committed by Miklos Szeredi
parent c55e0a55b1
commit 11ca77cdcc
1 changed files with 2 additions and 1 deletions

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@ -15,7 +15,8 @@ The direct-io mode can be selected with the FOPEN_DIRECT_IO flag in the
FUSE_OPEN reply.
In direct-io mode the page cache is completely bypassed for reads and writes.
No read-ahead takes place. Shared mmap is disabled.
No read-ahead takes place. Shared mmap is disabled by default. To allow shared
mmap, the FUSE_DIRECT_IO_ALLOW_MMAP flag may be enabled in the FUSE_INIT reply.
In cached mode reads may be satisfied from the page cache, and data may be
read-ahead by the kernel to fill the cache. The cache is always kept consistent