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| author | NeilBrown <neilb@suse.de> | 2024-03-25 06:36:05 +0100 |
|---|---|---|
| committer | Trond Myklebust <trond.myklebust@hammerspace.com> | 2024-05-20 17:09:20 +0200 |
| commit | 7c6c5249f061b64fc6b5b90bc147169a048691bf (patch) | |
| tree | 4cee132b6fdee4725ba9f47071c21be42c1f0bf4 /include | |
| parent | pNFS/filelayout: Specify the layout segment range in LAYOUTGET (diff) | |
| download | linux-7c6c5249f061b64fc6b5b90bc147169a048691bf.tar.xz linux-7c6c5249f061b64fc6b5b90bc147169a048691bf.zip | |
NFS: add atomic_open for NFSv3 to handle O_TRUNC correctly.
With two clients, each with NFSv3 mounts of the same directory, the sequence:
client1 client2
ls -l afile
echo hello there > afile
echo HELLO > afile
cat afile
will show
HELLO
there
because the O_TRUNC requested in the final 'echo' doesn't take effect.
This is because the "Negative dentry, just create a file" section in
lookup_open() assumes that the file *does* get created since the dentry
was negative, so it sets FMODE_CREATED, and this causes do_open() to
clear O_TRUNC and so the file doesn't get truncated.
Even mounting with -o lookupcache=none does not help as
nfs_neg_need_reval() always returns false if LOOKUP_CREATE is set.
This patch fixes the problem by providing an atomic_open inode operation
for NFSv3 (and v2). The code is largely the code from the branch in
lookup_open() when atomic_open is not provided. The significant change
is that the O_TRUNC flag is passed a new nfs_do_create() which add
'trunc' handling to nfs_create().
With this change we also optimise away an unnecessary LOOKUP before the
file is created.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/nfs_fs.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h index d59116ac8209..039898d70954 100644 --- a/include/linux/nfs_fs.h +++ b/include/linux/nfs_fs.h @@ -561,6 +561,9 @@ extern int nfs_may_open(struct inode *inode, const struct cred *cred, int openfl extern void nfs_access_zap_cache(struct inode *inode); extern int nfs_access_get_cached(struct inode *inode, const struct cred *cred, u32 *mask, bool may_block); +extern int nfs_atomic_open_v23(struct inode *dir, struct dentry *dentry, + struct file *file, unsigned int open_flags, + umode_t mode); /* * linux/fs/nfs/symlink.c |