Messages in this thread | | | Date | Tue, 2 Jan 2024 22:04:12 +0800 | Subject | Re: [PATCH v5 33/40] netfs, cachefiles: Pass upper bound length to allow expansion | From | Gao Xiang <> |
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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@redhat.com> > Reviewed-by: Jeff Layton <jlayton@kernel.org> > cc: linux-cachefs@redhat.com > cc: linux-fsdevel@vger.kernel.org > cc: linux-mm@kvack.org > --- > 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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