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| author |   Al Viro <viro@zeniv.linux.org.uk> | 2016-04-20 23:08:32 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2016-05-02 19:49:29 -0400 |
| commit | 6192269444ebfbfb42e23c7a6a93c76ffe4b5e51 (patch) | |
| tree | ec40fbbad46725d88f2c16b11ff5976d87f497bb /Documentation/filesystems | |
| parent | give readdir(2)/getdents(2)/etc. uniform exclusion with lseek() (diff) | |
| download | linux-dev-6192269444ebfbfb42e23c7a6a93c76ffe4b5e51.tar.xz linux-dev-6192269444ebfbfb42e23c7a6a93c76ffe4b5e51.zip | |
introduce a parallel variant of ->iterate()
New method: ->iterate_shared(). Same arguments as in ->iterate(),
called with the directory locked only shared. Once all filesystems
switch, the old one will be gone.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/porting | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting index 1567a53857bd..12c57abdaac9 100644 --- a/Documentation/filesystems/porting +++ b/Documentation/filesystems/porting @@ -557,3 +557,21 @@ in your dentry operations instead. will not happen in parallel ("same" in the sense of your ->d_compare()). Lookups on different names in the same directory can and do happen in parallel now. +-- +[recommended] + ->iterate_shared() is added; it's a parallel variant of ->iterate(). + Exclusion on struct file level is still provided (as well as that + between it and lseek on the same struct file), but if your directory + has been opened several times, you can get these called in parallel. + Exclusion between that method and all directory-modifying ones is + still provided, of course. + + Often enough ->iterate() can serve as ->iterate_shared() without any + changes - it is a read-only operation, after all. If you have any + per-inode or per-dentry in-core data structures modified by ->iterate(), + you might need something to serialize the access to them. If you + do dcache pre-seeding, you'll need to switch to d_alloc_parallel() for + that; look for in-tree examples. + + Old method is only used if the new one is absent; eventually it will + be removed. Switch while you still can; the old one won't stay. |