eCryptfs: delay writing 0's after llseek until write
Delay writing 0's out in eCryptfs after a seek past the end of the file
until data is actually written.
http://www.opengroup.org/onlinepubs/009695399/functions/lseek.html
``The lseek() function shall not, by itself, extend the size of a
file.''
Without this fix, applications that lseek() past the end of the file without
writing will experience unexpected behavior.
Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/ecryptfs/file.c b/fs/ecryptfs/file.c
index 9881b5c..59288d8 100644
--- a/fs/ecryptfs/file.c
+++ b/fs/ecryptfs/file.c
@@ -33,63 +33,6 @@
#include "ecryptfs_kernel.h"
/**
- * ecryptfs_llseek
- * @file: File we are seeking in
- * @offset: The offset to seek to
- * @origin: 2 - offset from i_size; 1 - offset from f_pos
- *
- * Returns the position we have seeked to, or negative on error
- */
-static loff_t ecryptfs_llseek(struct file *file, loff_t offset, int origin)
-{
- loff_t rv;
- loff_t new_end_pos;
- int rc;
- int expanding_file = 0;
- struct inode *inode = file->f_mapping->host;
-
- /* If our offset is past the end of our file, we're going to
- * need to grow it so we have a valid length of 0's */
- new_end_pos = offset;
- switch (origin) {
- case 2:
- new_end_pos += i_size_read(inode);
- expanding_file = 1;
- break;
- case 1:
- new_end_pos += file->f_pos;
- if (new_end_pos > i_size_read(inode)) {
- ecryptfs_printk(KERN_DEBUG, "new_end_pos(=[0x%.16x]) "
- "> i_size_read(inode)(=[0x%.16x])\n",
- new_end_pos, i_size_read(inode));
- expanding_file = 1;
- }
- break;
- default:
- if (new_end_pos > i_size_read(inode)) {
- ecryptfs_printk(KERN_DEBUG, "new_end_pos(=[0x%.16x]) "
- "> i_size_read(inode)(=[0x%.16x])\n",
- new_end_pos, i_size_read(inode));
- expanding_file = 1;
- }
- }
- ecryptfs_printk(KERN_DEBUG, "new_end_pos = [0x%.16x]\n", new_end_pos);
- if (expanding_file) {
- rc = ecryptfs_truncate(file->f_path.dentry, new_end_pos);
- if (rc) {
- rv = rc;
- ecryptfs_printk(KERN_ERR, "Error on attempt to "
- "truncate to (higher) offset [0x%.16x];"
- " rc = [%d]\n", new_end_pos, rc);
- goto out;
- }
- }
- rv = generic_file_llseek(file, offset, origin);
-out:
- return rv;
-}
-
-/**
* ecryptfs_read_update_atime
*
* generic_file_read updates the atime of upper layer inode. But, it
@@ -425,7 +368,7 @@
};
const struct file_operations ecryptfs_main_fops = {
- .llseek = ecryptfs_llseek,
+ .llseek = generic_file_llseek,
.read = do_sync_read,
.aio_read = ecryptfs_read_update_atime,
.write = do_sync_write,