| Message ID | 164678185692.1200972.597611902374126174.stgit@warthog.procyon.org.uk |
|---|---|
| Headers | show |
| Series | netfs: Prep for write helpers | expand |
On 3/9/22 11:26 PM, Jeff Layton wrote: > On Tue, 2022-03-08 at 23:25 +0000, David Howells wrote: >> From: Jeffle Xu <jefflexu@linux.alibaba.com> >> >> Export fscache_end_operation() to avoid code duplication. >> >> Besides, considering the paired fscache_begin_read_operation() is >> already exported, it shall make sense to also export >> fscache_end_operation(). >> > > Not what I think of when you say "exporting" but the patch itself looks > fine. > Yes, maybe "fscache: make fscache_end_operation() generally available" as David said shall be better...
Having had a go at implementing write helpers and content encryption support in netfslib, it seems that the netfs_read_{,sub}request structs and the equivalent write request structs were almost the same and so should be merged, thereby requiring only one set of alloc/get/put functions and a common set of tracepoints. Merging the structs also has the advantage that if a bounce buffer is added to the request struct, a read operation can be performed to fill the bounce buffer, the contents of the buffer can be modified and then a write operation can be performed on it to send the data wherever it needs to go using the same request structure all the way through. The I/O handlers would then transparently perform any required crypto. This should make it easy to perform RMW cycles if needed. The potentially common functions and structs, however, by their names all proclaim themselves to be associated with the read side of things. The bulk of these changes alter this in the following ways: (1) Rename struct netfs_read_{,sub}request to netfs_io_{,sub}request. (2) Rename some enums, members and flags to make them more appropriate. (3) Adjust some comments to match. (4) Drop "read"/"rreq" from the names of common functions. For instance, netfs_get_read_request() becomes netfs_get_request(). (5) The ->init_rreq() and ->issue_op() methods become ->init_request() and ->issue_read(). I've kept the latter as a read-specific function and in another branch added an ->issue_write() method. The driver source is then reorganised into a number of files: fs/netfs/buffered_read.c Create read reqs to the pagecache fs/netfs/io.c Dispatchers for read and write reqs fs/netfs/main.c Some general miscellaneous bits fs/netfs/objects.c Alloc, get and put functions fs/netfs/stats.c Optional procfs statistics. and future development can be fitted into this scheme, e.g.: fs/netfs/buffered_write.c Modify the pagecache fs/netfs/buffered_flush.c Writeback from the pagecache fs/netfs/direct_read.c DIO read support fs/netfs/direct_write.c DIO write support fs/netfs/unbuffered_write.c Write modifications directly back Beyond the above changes, there are also some changes that affect how things work: (1) Make fscache_end_operation() generally available. (2) In the netfs tracing header, generate enums from the symbol -> string mapping tables rather than manually coding them. (3) Add a struct for filesystems that uses netfslib to put into their inode wrapper structs to hold extra state that netfslib is interested in, such as the fscache cookie. This allows netfslib functions to be set in filesystem operation tables and jumped to directly without having to have a filesystem wrapper. (4) Add a member to the struct added in (3) to track the remote inode length as that may differ if local modifications are buffered. We may need to supply an appropriate EOF pointer when storing data (in AFS for example). (5) Pass extra information to netfs_alloc_request() so that the ->init_request() hook can access it and retain information to indicate the origin of the operation. (6) Make the ->init_request() hook return an error, thereby allowing a filesystem that isn't allowed to cache an inode (ceph or cifs, for example) to skip readahead. (7) Switch to using refcount_t for subrequests and add tracepoints to log refcount changes for the request and subrequest structs. (8) Add a function to consolidate dispatching a read request. Similar code is used in three places and another couple are likely to be added in the future. The patches can be found on this branch: http://git.kernel.org/cgit/linux/kernel/git/dhowells/linux-fs.git/log/?h=fscache-next This is based on top of ceph's master branch as some of the patches conflict. David --- Changes ======= ver #2) - Change kdoc references to renamed files[1]. - Switched the begin-read-function patch and the prepare-to-split patch as fewer functions then need unstatic'ing. - Fixed an uninitialised var in netfs_begin_read()[2][3]. - Fixed a refleak caused by an unremoved line when netfs_begin_read() was introduced. - Use "#if IS_ENABLED()" in netfs_i_cookie(), not "#ifdef". - Implemented missing bit of ceph readahead through netfs_readahead(). - Rearranged the patch order to make the ceph readahead possible. Link: https://lore.kernel.org/r/20220303202811.6a1d53a1@canb.auug.org.au/ [1] Link: https://lore.kernel.org/r/20220303163826.1120936-1-nathan@kernel.org/ [2] Link: https://lore.kernel.org/r/20220303235647.1297171-1-colin.i.king@gmail.com/ [3] Link: https://lore.kernel.org/r/164622970143.3564931.3656393397237724303.stgit@warthog.procyon.org.uk/ # v1 --- David Howells (17): netfs: Generate enums from trace symbol mapping lists netfs: Rename netfs_read_*request to netfs_io_*request netfs: Finish off rename of netfs_read_request to netfs_io_request netfs: Split netfs_io_* object handling out netfs: Adjust the netfs_rreq tracepoint slightly netfs: Trace refcounting on the netfs_io_request struct netfs: Trace refcounting on the netfs_io_subrequest struct netfs: Adjust the netfs_failure tracepoint to indicate non-subreq lines netfs: Change ->init_request() to return an error code netfs: Add a netfs inode context netfs: Add a function to consolidate beginning a read netfs: Prepare to split read_helper.c netfs: Rename read_helper.c to io.c netfs: Split fs/netfs/read_helper.c netfs: Split some core bits out into their own file netfs: Keep track of the actual remote file size afs: Maintain netfs_i_context::remote_i_size Jeff Layton (1): netfs: Refactor arguments for netfs_alloc_read_request Jeffle Xu (1): fscache: export fscache_end_operation() Documentation/filesystems/netfs_library.rst | 139 ++- fs/9p/cache.c | 10 +- fs/9p/v9fs.c | 4 +- fs/9p/v9fs.h | 12 +- fs/9p/vfs_addr.c | 62 +- fs/9p/vfs_inode.c | 13 +- fs/afs/dynroot.c | 1 + fs/afs/file.c | 41 +- fs/afs/inode.c | 32 +- fs/afs/internal.h | 23 +- fs/afs/super.c | 4 +- fs/afs/write.c | 10 +- fs/cachefiles/io.c | 10 +- fs/ceph/addr.c | 113 +- fs/ceph/cache.c | 28 +- fs/ceph/cache.h | 15 +- fs/ceph/inode.c | 6 +- fs/ceph/super.h | 16 +- fs/cifs/cifsglob.h | 10 +- fs/cifs/fscache.c | 19 +- fs/cifs/fscache.h | 2 +- fs/fscache/internal.h | 11 - fs/netfs/Makefile | 8 +- fs/netfs/buffered_read.c | 428 +++++++ fs/netfs/internal.h | 49 +- fs/netfs/io.c | 657 ++++++++++ fs/netfs/main.c | 20 + fs/netfs/objects.c | 161 +++ fs/netfs/read_helper.c | 1205 ------------------- fs/netfs/stats.c | 1 - fs/nfs/fscache.c | 8 - include/linux/fscache.h | 14 + include/linux/netfs.h | 162 ++- include/trace/events/cachefiles.h | 6 +- include/trace/events/netfs.h | 188 ++- 35 files changed, 1860 insertions(+), 1628 deletions(-) create mode 100644 fs/netfs/buffered_read.c create mode 100644 fs/netfs/io.c create mode 100644 fs/netfs/main.c create mode 100644 fs/netfs/objects.c delete mode 100644 fs/netfs/read_helper.c