diff options
Diffstat (limited to 'fs/read_write.c')
-rw-r--r-- | fs/read_write.c | 82 |
1 files changed, 50 insertions, 32 deletions
diff --git a/fs/read_write.c b/fs/read_write.c index 179f1c33ea5..5ad4248b0cd 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -35,23 +35,45 @@ static inline int unsigned_offsets(struct file *file) return file->f_mode & FMODE_UNSIGNED_OFFSET; } +static loff_t lseek_execute(struct file *file, struct inode *inode, + loff_t offset, loff_t maxsize) +{ + if (offset < 0 && !unsigned_offsets(file)) + return -EINVAL; + if (offset > maxsize) + return -EINVAL; + + if (offset != file->f_pos) { + file->f_pos = offset; + file->f_version = 0; + } + return offset; +} + /** - * generic_file_llseek_unlocked - lockless generic llseek implementation + * generic_file_llseek_size - generic llseek implementation for regular files * @file: file structure to seek on * @offset: file offset to seek to * @origin: type of seek + * @size: max size of file system + * + * This is a variant of generic_file_llseek that allows passing in a custom + * file size. * - * Updates the file offset to the value specified by @offset and @origin. - * Locking must be provided by the caller. + * Synchronization: + * SEEK_SET and SEEK_END are unsynchronized (but atomic on 64bit platforms) + * SEEK_CUR is synchronized against other SEEK_CURs, but not read/writes. + * read/writes behave like SEEK_SET against seeks. */ loff_t -generic_file_llseek_unlocked(struct file *file, loff_t offset, int origin) +generic_file_llseek_size(struct file *file, loff_t offset, int origin, + loff_t maxsize) { struct inode *inode = file->f_mapping->host; switch (origin) { case SEEK_END: - offset += inode->i_size; + offset += i_size_read(inode); break; case SEEK_CUR: /* @@ -62,14 +84,22 @@ generic_file_llseek_unlocked(struct file *file, loff_t offset, int origin) */ if (offset == 0) return file->f_pos; - offset += file->f_pos; - break; + /* + * f_lock protects against read/modify/write race with other + * SEEK_CURs. Note that parallel writes and reads behave + * like SEEK_SET. + */ + spin_lock(&file->f_lock); + offset = lseek_execute(file, inode, file->f_pos + offset, + maxsize); + spin_unlock(&file->f_lock); + return offset; case SEEK_DATA: /* * In the generic case the entire file is data, so as long as * offset isn't at the end of the file then the offset is data. */ - if (offset >= inode->i_size) + if (offset >= i_size_read(inode)) return -ENXIO; break; case SEEK_HOLE: @@ -77,26 +107,15 @@ generic_file_llseek_unlocked(struct file *file, loff_t offset, int origin) * There is a virtual hole at the end of the file, so as long as * offset isn't i_size or larger, return i_size. */ - if (offset >= inode->i_size) + if (offset >= i_size_read(inode)) return -ENXIO; - offset = inode->i_size; + offset = i_size_read(inode); break; } - if (offset < 0 && !unsigned_offsets(file)) - return -EINVAL; - if (offset > inode->i_sb->s_maxbytes) - return -EINVAL; - - /* Special lock needed here? */ - if (offset != file->f_pos) { - file->f_pos = offset; - file->f_version = 0; - } - - return offset; + return lseek_execute(file, inode, offset, maxsize); } -EXPORT_SYMBOL(generic_file_llseek_unlocked); +EXPORT_SYMBOL(generic_file_llseek_size); /** * generic_file_llseek - generic llseek implementation for regular files @@ -110,13 +129,10 @@ EXPORT_SYMBOL(generic_file_llseek_unlocked); */ loff_t generic_file_llseek(struct file *file, loff_t offset, int origin) { - loff_t rval; - - mutex_lock(&file->f_dentry->d_inode->i_mutex); - rval = generic_file_llseek_unlocked(file, offset, origin); - mutex_unlock(&file->f_dentry->d_inode->i_mutex); + struct inode *inode = file->f_mapping->host; - return rval; + return generic_file_llseek_size(file, offset, origin, + inode->i_sb->s_maxbytes); } EXPORT_SYMBOL(generic_file_llseek); @@ -617,7 +633,8 @@ ssize_t do_loop_readv_writev(struct file *filp, struct iovec *iov, ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector, unsigned long nr_segs, unsigned long fast_segs, struct iovec *fast_pointer, - struct iovec **ret_pointer) + struct iovec **ret_pointer, + int check_access) { unsigned long seg; ssize_t ret; @@ -673,7 +690,8 @@ ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector, ret = -EINVAL; goto out; } - if (unlikely(!access_ok(vrfy_dir(type), buf, len))) { + if (check_access + && unlikely(!access_ok(vrfy_dir(type), buf, len))) { ret = -EFAULT; goto out; } @@ -705,7 +723,7 @@ static ssize_t do_readv_writev(int type, struct file *file, } ret = rw_copy_check_uvector(type, uvector, nr_segs, - ARRAY_SIZE(iovstack), iovstack, &iov); + ARRAY_SIZE(iovstack), iovstack, &iov, 1); if (ret <= 0) goto out; |