diff options
| author | David Howells <dhowells@redhat.com> | 2026-10-08 19:16:34 +0100 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2026-10-16 11:02:26 +0200 |
| commit | b6134f76740497004f72954ae67bd4ba45d2f044 (patch) | |
| tree | 1fc99382d13d2a5efae38f0a47f8170861c92211 /Documentation/filesystems | |
| parent | 9310c6d7cdbbce55c254c935862fd66dc26a730a (diff) | |
fscache, cachefiles: Fix resize handling
Fix the resize handling in fscache and cachefiles by passing down a flag to
indicate if the file is being shrunk as the cache's idea of how big the
file should be may be stale and thus not useful in comparison to the
object's size.
The issue is that netfs_perform_write() updates the network filesystem's
file's i_size as it adds data to the pagecache, but the cache isn't updated
until writeback flushes that data. A truncation may then scrap that data
and so the cache never sees it and doesn't update before it is told to
resize. In the resize, cachefiles was comparing the new size against the
current cache size and then thinking the file was being expanded.
Note that this is a bit more complicated for ceph than other filesystems as
ceph splits the truncation of the local pagecache and fscache to after the
RPC reply handler has updated the inode record - the reply handler
communicates the need for the truncation finalisation through ceph inode
flags.
To this end, ceph is changed such that the outstanding truncation count in the
inode turns into a bool and just set instead of being incremented (the code
only cares if it's zero or non-zero) and then a second bool is added to record
if the file was being shrunk.
Reported-by: Marc Dionne <marc.dionne@auristor.com>
Fixes: 1a9fe4b6e787 ("cachefiles: Don't rely on backing fs storage map for most use cases")
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/1091807.1791483394@warthog.procyon.org.uk
Reviewed-by: Alex Markuze <amarkuze@redhat.com>
cc: Ilya Dryomov <idryomov@gmail.com>
cc: Alex Markuze <amarkuze@redhat.com>
cc: Viacheslav Dubeyko <slava@dubeyko.com>
cc: Paulo Alcantara <pc@manguebit.org>
cc: Matthew Wilcox <willy@infradead.org>
cc: v9fs@lists.linux.dev
cc: linux-afs@lists.infradead.org
cc: ceph-devel@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/caching/backend-api.rst | 2 | ||||
| -rw-r--r-- | Documentation/filesystems/caching/netfs-api.rst | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/Documentation/filesystems/caching/backend-api.rst b/Documentation/filesystems/caching/backend-api.rst index 3a199fc50828..df837531b3fd 100644 --- a/Documentation/filesystems/caching/backend-api.rst +++ b/Documentation/filesystems/caching/backend-api.rst @@ -339,7 +339,7 @@ pointers to methods to allow fscache to request management of the cache: * Change the size of a data storage object [mandatory]:: void (*resize_cookie)(struct netfs_cache_resources *cres, - loff_t new_size); + loff_t new_size, bool shrank); This method is called to inform the cache backend of a change in size of the netfs file due to local truncation. The cache backend should make all diff --git a/Documentation/filesystems/caching/netfs-api.rst b/Documentation/filesystems/caching/netfs-api.rst index 665b27f1556e..3154a1686480 100644 --- a/Documentation/filesystems/caching/netfs-api.rst +++ b/Documentation/filesystems/caching/netfs-api.rst @@ -226,7 +226,7 @@ If a network filesystem file is resized locally by truncation, the following should be called to notify the cache:: void fscache_resize_cookie(struct fscache_cookie *cookie, - loff_t new_size); + loff_t new_size, bool shrank); The caller must have first marked the cookie in-use. The cookie and the new size are passed in and the cache is synchronously resized. This is expected to |