diff options
Diffstat (limited to 'fs/open.c')
-rw-r--r-- | fs/open.c | 29 |
1 files changed, 28 insertions, 1 deletions
diff --git a/fs/open.c b/fs/open.c index b5b80469b93d..b62f5c0923a8 100644 --- a/fs/open.c +++ b/fs/open.c @@ -374,6 +374,25 @@ long do_faccessat(int dfd, const char __user *filename, int mode) override_cred->cap_permitted; } + /* + * The new set of credentials can *only* be used in + * task-synchronous circumstances, and does not need + * RCU freeing, unless somebody then takes a separate + * reference to it. + * + * NOTE! This is _only_ true because this credential + * is used purely for override_creds() that installs + * it as the subjective cred. Other threads will be + * accessing ->real_cred, not the subjective cred. + * + * If somebody _does_ make a copy of this (using the + * 'get_current_cred()' function), that will clear the + * non_rcu field, because now that other user may be + * expecting RCU freeing. But normal thread-synchronous + * cred accesses will keep things non-RCY. + */ + override_cred->non_rcu = 1; + old_cred = override_creds(override_cred); retry: res = user_path_at(dfd, filename, lookup_flags, &path); @@ -757,7 +776,7 @@ static int do_dentry_open(struct file *f, f->f_mode |= FMODE_ATOMIC_POS; f->f_op = fops_get(inode->i_fop); - if (unlikely(WARN_ON(!f->f_op))) { + if (WARN_ON(!f->f_op)) { error = -ENODEV; goto cleanup_all; } @@ -799,6 +818,14 @@ static int do_dentry_open(struct file *f, if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO) return -EINVAL; } + + /* + * XXX: Huge page cache doesn't support writing yet. Drop all page + * cache for this file before processing writes. + */ + if ((f->f_mode & FMODE_WRITE) && filemap_nr_thps(inode->i_mapping)) + truncate_pagecache(inode, 0); + return 0; cleanup_all: |