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https://github.com/torvalds/linux
synced 2024-09-06 09:51:23 +00:00
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>
This commit is contained in:
parent
464b424fb0
commit
7c6c5249f0
54
fs/nfs/dir.c
54
fs/nfs/dir.c
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@ -56,6 +56,8 @@ static int nfs_readdir(struct file *, struct dir_context *);
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static int nfs_fsync_dir(struct file *, loff_t, loff_t, int);
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static int nfs_fsync_dir(struct file *, loff_t, loff_t, int);
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static loff_t nfs_llseek_dir(struct file *, loff_t, int);
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static loff_t nfs_llseek_dir(struct file *, loff_t, int);
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static void nfs_readdir_clear_array(struct folio *);
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static void nfs_readdir_clear_array(struct folio *);
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static int nfs_do_create(struct inode *dir, struct dentry *dentry,
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umode_t mode, int open_flags);
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const struct file_operations nfs_dir_operations = {
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const struct file_operations nfs_dir_operations = {
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.llseek = nfs_llseek_dir,
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.llseek = nfs_llseek_dir,
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@ -2243,6 +2245,41 @@ static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags)
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#endif /* CONFIG_NFSV4 */
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#endif /* CONFIG_NFSV4 */
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int nfs_atomic_open_v23(struct inode *dir, struct dentry *dentry,
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struct file *file, unsigned int open_flags,
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umode_t mode)
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{
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/* Same as look+open from lookup_open(), but with different O_TRUNC
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* handling.
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*/
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int error = 0;
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if (open_flags & O_CREAT) {
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file->f_mode |= FMODE_CREATED;
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error = nfs_do_create(dir, dentry, mode, open_flags);
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if (error)
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return error;
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return finish_open(file, dentry, NULL);
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} else if (d_in_lookup(dentry)) {
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/* The only flags nfs_lookup considers are
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* LOOKUP_EXCL and LOOKUP_RENAME_TARGET, and
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* we want those to be zero so the lookup isn't skipped.
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*/
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struct dentry *res = nfs_lookup(dir, dentry, 0);
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d_lookup_done(dentry);
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if (unlikely(res)) {
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if (IS_ERR(res))
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return PTR_ERR(res);
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return finish_no_open(file, res);
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}
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}
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return finish_no_open(file, NULL);
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}
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EXPORT_SYMBOL_GPL(nfs_atomic_open_v23);
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struct dentry *
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struct dentry *
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nfs_add_or_obtain(struct dentry *dentry, struct nfs_fh *fhandle,
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nfs_add_or_obtain(struct dentry *dentry, struct nfs_fh *fhandle,
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struct nfs_fattr *fattr)
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struct nfs_fattr *fattr)
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@ -2303,18 +2340,23 @@ EXPORT_SYMBOL_GPL(nfs_instantiate);
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* that the operation succeeded on the server, but an error in the
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* that the operation succeeded on the server, but an error in the
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* reply path made it appear to have failed.
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* reply path made it appear to have failed.
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*/
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*/
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int nfs_create(struct mnt_idmap *idmap, struct inode *dir,
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static int nfs_do_create(struct inode *dir, struct dentry *dentry,
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struct dentry *dentry, umode_t mode, bool excl)
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umode_t mode, int open_flags)
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{
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{
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struct iattr attr;
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struct iattr attr;
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int open_flags = excl ? O_CREAT | O_EXCL : O_CREAT;
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int error;
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int error;
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open_flags |= O_CREAT;
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dfprintk(VFS, "NFS: create(%s/%lu), %pd\n",
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dfprintk(VFS, "NFS: create(%s/%lu), %pd\n",
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dir->i_sb->s_id, dir->i_ino, dentry);
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dir->i_sb->s_id, dir->i_ino, dentry);
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attr.ia_mode = mode;
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attr.ia_mode = mode;
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attr.ia_valid = ATTR_MODE;
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attr.ia_valid = ATTR_MODE;
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if (open_flags & O_TRUNC) {
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attr.ia_size = 0;
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attr.ia_valid |= ATTR_SIZE;
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}
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trace_nfs_create_enter(dir, dentry, open_flags);
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trace_nfs_create_enter(dir, dentry, open_flags);
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error = NFS_PROTO(dir)->create(dir, dentry, &attr, open_flags);
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error = NFS_PROTO(dir)->create(dir, dentry, &attr, open_flags);
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@ -2326,6 +2368,12 @@ int nfs_create(struct mnt_idmap *idmap, struct inode *dir,
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d_drop(dentry);
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d_drop(dentry);
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return error;
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return error;
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}
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}
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int nfs_create(struct mnt_idmap *idmap, struct inode *dir,
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struct dentry *dentry, umode_t mode, bool excl)
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{
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return nfs_do_create(dir, dentry, mode, excl ? O_EXCL : 0);
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}
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EXPORT_SYMBOL_GPL(nfs_create);
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EXPORT_SYMBOL_GPL(nfs_create);
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/*
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/*
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@ -986,6 +986,7 @@ static int nfs3_have_delegation(struct inode *inode, fmode_t flags)
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static const struct inode_operations nfs3_dir_inode_operations = {
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static const struct inode_operations nfs3_dir_inode_operations = {
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.create = nfs_create,
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.create = nfs_create,
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.atomic_open = nfs_atomic_open_v23,
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.lookup = nfs_lookup,
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.lookup = nfs_lookup,
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.link = nfs_link,
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.link = nfs_link,
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.unlink = nfs_unlink,
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.unlink = nfs_unlink,
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@ -695,6 +695,7 @@ static int nfs_have_delegation(struct inode *inode, fmode_t flags)
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static const struct inode_operations nfs_dir_inode_operations = {
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static const struct inode_operations nfs_dir_inode_operations = {
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.create = nfs_create,
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.create = nfs_create,
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.lookup = nfs_lookup,
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.lookup = nfs_lookup,
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.atomic_open = nfs_atomic_open_v23,
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.link = nfs_link,
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.link = nfs_link,
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.unlink = nfs_unlink,
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.unlink = nfs_unlink,
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.symlink = nfs_symlink,
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.symlink = nfs_symlink,
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@ -561,6 +561,9 @@ extern int nfs_may_open(struct inode *inode, const struct cred *cred, int openfl
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extern void nfs_access_zap_cache(struct inode *inode);
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extern void nfs_access_zap_cache(struct inode *inode);
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extern int nfs_access_get_cached(struct inode *inode, const struct cred *cred,
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extern int nfs_access_get_cached(struct inode *inode, const struct cred *cred,
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u32 *mask, bool may_block);
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u32 *mask, bool may_block);
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extern int nfs_atomic_open_v23(struct inode *dir, struct dentry *dentry,
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struct file *file, unsigned int open_flags,
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umode_t mode);
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/*
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/*
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* linux/fs/nfs/symlink.c
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* linux/fs/nfs/symlink.c
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