Hi David,
On 2023/12/21 21:23, David Howells wrote:
Make netfslib pass the maximum length to the ->prepare_write() op to tell
the cache how much it can expand the length of a write to. This allows a
write to the server at the end of a file to be limited to a few bytes
whilst writing an entire block to the cache (something required by direct
I/O).
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
cc: linux-cachefs@xxxxxxxxxx
cc: linux-fsdevel@xxxxxxxxxxxxxxx
cc: linux-mm@xxxxxxxxx
---
fs/cachefiles/internal.h | 2 +-
fs/cachefiles/io.c | 10 ++++++----
fs/cachefiles/ondemand.c | 2 +-
fs/netfs/fscache_io.c | 2 +-
fs/netfs/io.c | 2 +-
fs/netfs/objects.c | 1 +
fs/netfs/output.c | 25 ++++++++++---------------
fs/smb/client/fscache.c | 2 +-
include/linux/netfs.h | 5 +++--
9 files changed, 25 insertions(+), 26 deletions(-)
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
index 2ad58c465208..1af48d576a34 100644
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -233,7 +233,7 @@ extern bool cachefiles_begin_operation(struct netfs_cache_resources *cres,
enum fscache_want_state want_state);
extern int __cachefiles_prepare_write(struct cachefiles_object *object,
struct file *file,
- loff_t *_start, size_t *_len,
+ loff_t *_start, size_t *_len, size_t upper_len,
bool no_space_allocated_yet);
extern int __cachefiles_write(struct cachefiles_object *object,
struct file *file,
diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c
index 009d23cd435b..bffffedce4a9 100644
--- a/fs/cachefiles/io.c
+++ b/fs/cachefiles/io.c
@@ -518,7 +518,7 @@ cachefiles_prepare_ondemand_read(struct netfs_cache_resources *cres,
*/
int __cachefiles_prepare_write(struct cachefiles_object *object,
struct file *file,
- loff_t *_start, size_t *_len,
+ loff_t *_start, size_t *_len, size_t upper_len,
bool no_space_allocated_yet)
{
struct cachefiles_cache *cache = object->volume->cache;
@@ -530,6 +530,8 @@ int __cachefiles_prepare_write(struct cachefiles_object *object,
down = start - round_down(start, PAGE_SIZE);
*_start = start - down;
*_len = round_up(down + len, PAGE_SIZE);
+ if (down < start || *_len > upper_len)
+ return -ENOBUFS;
Sorry for bothering. We just found some strange when testing
today-next EROFS over fscache.
I'm not sure the meaning of
if (down < start
For example, if start is page-aligned, down == 0.
so as long as start > 0 and page-aligned, it will return
-ENOBUFS. Does it an intended behavior?
Thanks,
Gao Xiang
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