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author | Tejun Heo <tj@kernel.org> | 2014-02-03 14:09:13 -0500 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-02-07 15:52:48 -0800 |
commit | 4d3773c4bb41ed5228f1ab7a4a52b79e17b10515 (patch) | |
tree | 71c30d7009b36d22e9aab816f3dc7e373bb5f1e9 /include | |
parent | d35258ef702cca0c4e66d799f8e38b78c02ce8a5 (diff) | |
download | linux-stable-4d3773c4bb41ed5228f1ab7a4a52b79e17b10515.tar.gz linux-stable-4d3773c4bb41ed5228f1ab7a4a52b79e17b10515.tar.bz2 linux-stable-4d3773c4bb41ed5228f1ab7a4a52b79e17b10515.zip |
kernfs: implement kernfs_ops->atomic_write_len
A write to a kernfs_node is buffered through a kernel buffer. Writes
<= PAGE_SIZE are performed atomically, while larger ones are executed
in PAGE_SIZE chunks. While this is enough for sysfs, cgroup which is
scheduled to be converted to use kernfs needs a bit more control over
it.
This patch adds kernfs_ops->atomic_write_len. If not set (zero), the
behavior stays the same. If set, writes upto the size are executed
atomically and larger writes are rejected with -E2BIG.
A different implementation strategy would be allowing configuring
chunking size while making the original write size available to the
write method; however, such strategy, while being more complicated,
doesn't really buy anything. If the write implementation has to
handle chunking, the specific chunk size shouldn't matter all that
much.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/kernfs.h | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index 4520c86f5cb4..47f5235a097a 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -178,9 +178,13 @@ struct kernfs_ops { loff_t off); /* - * write() is bounced through kernel buffer and a write larger than - * PAGE_SIZE results in partial operation of PAGE_SIZE. + * write() is bounced through kernel buffer. If atomic_write_len + * is not set, a write larger than PAGE_SIZE results in partial + * operations of PAGE_SIZE chunks. If atomic_write_len is set, + * writes upto the specified size are executed atomically but + * larger ones are rejected with -E2BIG. */ + size_t atomic_write_len; ssize_t (*write)(struct kernfs_open_file *of, char *buf, size_t bytes, loff_t off); |