FUSE, as of now, makes aggressive lookup calls into libfuse in certain code paths. These lookup calls possibly can be avoided in some cases. Incoming two patches addresses the issue of aggressive lookup calls. First patch handles the case where we open first time a file/dir or create a file (O_CREAT) but do a lookup first on it. After lookup is performed we make another call into libfuse to open the file. Now these two separate calls into libfuse can be combined and performed as a single call into libfuse. Second patch handles the case when we are opening an already existing file (positive dentry). Before this open call, we re-validate the inode and this re-validation does a lookup on the file and verify the inode. This separate lookup also can be avoided (for non-dir) and combined with open call into libfuse. Here is the link to libfuse patches which implement atomic open https://github.com/d-hans/libfuse/commit/5255ce89decac71912e25b3cb4d79ebac538a456 https://github.com/d-hans/libfuse/commit/346b9feb2de5b6ff2b15882a38d7de0a0768c17c https://github.com/d-hans/libfuse/commit/ac010dac446a9267b619afb138ab315d6c6eeb3e Dharmendra Singh (2): FUSE: Implement atomic lookup + open FUSE: Avoid lookup in d_revalidate() fs/fuse/dir.c | 170 +++++++++++++++++++++++++++++++++----- fs/fuse/file.c | 30 ++++++- fs/fuse/fuse_i.h | 13 ++- fs/fuse/inode.c | 4 +- fs/fuse/ioctl.c | 2 +- include/uapi/linux/fuse.h | 2 + 6 files changed, 195 insertions(+), 26 deletions(-) -- 2.17.1
