kernel.git/fs/nfsd/filecache.h, branch linux-6.3.y

nfsd: fix handling of cached open files in nfsd4_open codepath

2023-01-06T18:17:06Z

Commit fb70bf124b05 ("NFSD: Instantiate a struct file when creating a regular NFSv4 file") added the ability to cache an open fd over a compound. There are a couple of problems with the way this currently works: It's racy, as a newly-created nfsd_file can end up with its PENDING bit cleared while the nf is hashed, and the nf_file pointer is still zeroed out. Other tasks can find it in this state and they expect to see a valid nf_file, and can oops if nf_file is NULL. Also, there is no guarantee that we'll end up creating a new nfsd_file if one is already in the hash. If an extant entry is in the hash with a valid nf_file, nfs4_get_vfs_file will clobber its nf_file pointer with the value of op_file and the old nf_file will leak. Fix both issues by making a new nfsd_file_acquirei_opened variant that takes an optional file pointer. If one is present when this is called, we'll take a new reference to it instead of trying to open the file. If the nfsd_file already has a valid nf_file, we'll just ignore the optional file and pass the nfsd_file back as-is. Also rework the tracepoints a bit to allow for an "opened" variant and don't try to avoid counting acquisitions in the case where we already have a cached open file. Fixes: fb70bf124b05 ("NFSD: Instantiate a struct file when creating a regular NFSv4 file") Cc: Trond Myklebust Reported-by: Stanislav Saner Reported-and-Tested-by: Ruben Vestergaard Reported-and-Tested-by: Torkil Svensgaard Signed-off-by: Jeff Layton Signed-off-by: Chuck Lever

NFSD: Add an NFSD_FILE_GC flag to enable nfsd_file garbage collection

2022-11-28T17:54:45Z

NFSv4 operations manage the lifetime of nfsd_file items they use by means of NFSv4 OPEN and CLOSE. Hence there's no need for them to be garbage collected. Introduce a mechanism to enable garbage collection for nfsd_file items used only by NFSv2/3 callers. Note that the change in nfsd_file_put() ensures that both CLOSE and DELEGRETURN will actually close out and free an nfsd_file on last reference of a non-garbage-collected file. Link: https://bugzilla.linux-nfs.org/show_bug.cgi?id=394 Suggested-by: Trond Myklebust Signed-off-by: Chuck Lever Tested-by: Jeff Layton Reviewed-by: NeilBrown Reviewed-by: Jeff Layton

NFSD: Revert "NFSD: NFSv4 CLOSE should release an nfsd_file immediately"

2022-11-28T17:54:45Z

This reverts commit 5e138c4a750dc140d881dab4a8804b094bbc08d2. That commit attempted to make files available to other users as soon as all NFSv4 clients were done with them, rather than waiting until the filecache LRU had garbage collected them. It gets the reference counting wrong, for one thing. But it also misses that DELEGRETURN should release a file in the same fashion. In fact, any nfsd_file_put() on an file held open by an NFSv4 client needs potentially to release the file immediately... Clear the way for implementing that idea. Signed-off-by: Chuck Lever Reviewed-by: Jeff Layton Reviewed-by: NeilBrown

nfsd: use DEFINE_SHOW_ATTRIBUTE to define nfsd_file_cache_stats_fops

2022-09-26T18:02:50Z

Use DEFINE_SHOW_ATTRIBUTE helper macro to simplify the code. Signed-off-by: ChenXiaoSong Signed-off-by: Chuck Lever

NFSD: Ensure nf_inode is never dereferenced

2022-07-30T00:16:56Z

The documenting comment for struct nf_file states: /* * A representation of a file that has been opened by knfsd. These are hashed * in the hashtable by inode pointer value. Note that this object doesn't * hold a reference to the inode by itself, so the nf_inode pointer should * never be dereferenced, only used for comparison. */ Replace the two existing dereferences to make the comment always true. Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever

NFSD: NFSv4 CLOSE should release an nfsd_file immediately

2022-07-30T00:16:42Z

The last close of a file should enable other accessors to open and use that file immediately. Leaving the file open in the filecache prevents other users from accessing that file until the filecache garbage-collects the file -- sometimes that takes several seconds. Reported-by: Wang Yugui Link: https://bugzilla.linux-nfs.org/show_bug.cgi?387 Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever

NFSD: Clean up unused code after rhashtable conversion

2022-07-30T00:15:38Z

Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever

NFSD: Set up an rhashtable for the filecache

2022-07-30T00:12:02Z

Add code to initialize and tear down an rhashtable. The rhashtable is not used yet. Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever

NFSD: Remove nfsd_file::nf_hashval

2022-07-30T00:12:01Z

The value in this field can always be computed from nf_inode, thus it is no longer used. Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever

NFSD: Report average age of filecache items

2022-07-30T00:09:22Z

This is a measure of how long items stay in the filecache, to help assess how efficient the cache is. Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever