From 3a8cff4f026c0b98bee6291eb28d4df42feb76dc Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 11 Aug 2008 15:37:17 +0200 Subject: [PATCH] generic_file_llseek tidyups Add kerneldoc for generic_file_llseek and generic_file_llseek_unlocked, use sane variable names and unclutter the code. Signed-off-by: Christoph Hellwig Signed-off-by: Al Viro --- fs/read_write.c | 58 +++++++++++++++++++++++++++++++++++++++------------------ 1 file changed, 40 insertions(+), 18 deletions(-) diff --git a/fs/read_write.c b/fs/read_write.c index 9ba495d5a29b..969a6d9c020b 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -31,39 +31,61 @@ const struct file_operations generic_ro_fops = { EXPORT_SYMBOL(generic_ro_fops); +/** + * generic_file_llseek_unlocked - lockless generic llseek implementation + * @file: file structure to seek on + * @offset: file offset to seek to + * @origin: type of seek + * + * Updates the file offset to the value specified by @offset and @origin. + * Locking must be provided by the caller. + */ loff_t generic_file_llseek_unlocked(struct file *file, loff_t offset, int origin) { - loff_t retval; struct inode *inode = file->f_mapping->host; switch (origin) { - case SEEK_END: - offset += inode->i_size; - break; - case SEEK_CUR: - offset += file->f_pos; + case SEEK_END: + offset += inode->i_size; + break; + case SEEK_CUR: + offset += file->f_pos; + break; } - retval = -EINVAL; - if (offset>=0 && offset<=inode->i_sb->s_maxbytes) { - /* Special lock needed here? */ - if (offset != file->f_pos) { - file->f_pos = offset; - file->f_version = 0; - } - retval = offset; + + if (offset < 0 || 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 retval; + + return offset; } EXPORT_SYMBOL(generic_file_llseek_unlocked); +/** + * generic_file_llseek - generic llseek implementation for regular files + * @file: file structure to seek on + * @offset: file offset to seek to + * @origin: type of seek + * + * This is a generic implemenation of ->llseek useable for all normal local + * filesystems. It just updates the file offset to the value specified by + * @offset and @origin under i_mutex. + */ loff_t generic_file_llseek(struct file *file, loff_t offset, int origin) { - loff_t n; + loff_t rval; + mutex_lock(&file->f_dentry->d_inode->i_mutex); - n = generic_file_llseek_unlocked(file, offset, origin); + rval = generic_file_llseek_unlocked(file, offset, origin); mutex_unlock(&file->f_dentry->d_inode->i_mutex); - return n; + + return rval; } EXPORT_SYMBOL(generic_file_llseek); -- cgit v1.2.2