On Tue, Sep 11, 2018 at 01:09:43PM +0200, Alexander Graf wrote:
On 11.09.18 08:59, Akashi, Takahiro wrote:
From: AKASHI Takahiro takahiro.akashi@linaro.org
In this patch, all the necessary code for allowing for a file offset at write is implemented. What plays a major roll here is get_set_cluster(), which, in contrast to its counterpart, set_cluster(), only operates on already-allocated clusters, overwriting with data.
So, with a file offset specified, set_contents() seeks and writes data with set_get_cluster() until the end of a file, and, once it reaches there, continues writing with set_cluster() for the rest.
Please note that a file will be trimmed as a result of write operation if write ends before reaching file's end. This is an intended behavior in order to maintain compatibility with the current interface.
Signed-off-by: AKASHI Takahiro takahiro.akashi@linaro.org
fs/fat/fat_write.c | 288 ++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 273 insertions(+), 15 deletions(-)
diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c index c22d8c7a46a1..651c7866debc 100644 --- a/fs/fat/fat_write.c +++ b/fs/fat/fat_write.c @@ -450,6 +450,121 @@ set_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer, return 0; }
+static __u8 tmpbuf_cluster[MAX_CLUSTSIZE] __aligned(ARCH_DMA_MINALIGN);
I'm not sure all systems that allow FAT writing will like the additional overhead this will incur.
Which part are you seeing as "overhead"? I know it's ugly but the same technique is also used in fat.c :)
Have you thrown your patch set into buildman to check all boards successfully build?
No, not at all.
Thanks, -Takahiro Akashi
Alex