[PATCH] ecryptfs: handle AOP_TRUNCATED_PAGE better

- In fact we don't have to fail if AOP_TRUNCATED_PAGE was returned from
  prepare_write or commit_write. It is beter to retry attempt where it
  is possible.

- Rearange ecryptfs_get_lower_page() error handling logic, make it more clean.

Signed-off-by: Dmitriy Monakhov <dmonakhov@openvz.org>
Acked-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/mmap.c b/fs/ecryptfs/mmap.c
index 7def4be..b731b09 100644 (file)
--- a/fs/ecryptfs/mmap.c
+++ b/fs/ecryptfs/mmap.c
@@ -446,6 +446,7 @@ static int ecryptfs_write_inode_size_to_header(struct file *lower_file,
        const struct address_space_operations *lower_a_ops;
        u64 file_size;
 
+retry:
        header_page = grab_cache_page(lower_inode->i_mapping, 0);
        if (!header_page) {
                ecryptfs_printk(KERN_ERR, "grab_cache_page for "
@@ -456,9 +457,10 @@ static int ecryptfs_write_inode_size_to_header(struct file *lower_file,
        lower_a_ops = lower_inode->i_mapping->a_ops;
        rc = lower_a_ops->prepare_write(lower_file, header_page, 0, 8);
        if (rc) {
-               if (rc == AOP_TRUNCATED_PAGE)
+               if (rc == AOP_TRUNCATED_PAGE) {
                        ecryptfs_release_lower_page(header_page, 0);
-               else
+                       goto retry;
+               } else
                        ecryptfs_release_lower_page(header_page, 1);
                goto out;
        }
@@ -473,9 +475,10 @@ static int ecryptfs_write_inode_size_to_header(struct file *lower_file,
        if (rc < 0)
                ecryptfs_printk(KERN_ERR, "Error commiting header page "
                                "write\n");
-       if (rc == AOP_TRUNCATED_PAGE)
+       if (rc == AOP_TRUNCATED_PAGE) {
                ecryptfs_release_lower_page(header_page, 0);
-       else
+               goto retry;
+       } else
                ecryptfs_release_lower_page(header_page, 1);
        lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
        mark_inode_dirty_sync(inode);
@@ -565,6 +568,7 @@ int ecryptfs_get_lower_page(struct page **lower_page, struct inode *lower_inode,
 {
        int rc = 0;
 
+retry:
        *lower_page = grab_cache_page(lower_inode->i_mapping, lower_page_index);
        if (!(*lower_page)) {
                rc = -EINVAL;
@@ -578,18 +582,18 @@ int ecryptfs_get_lower_page(struct page **lower_page, struct inode *lower_inode,
                                                          byte_offset,
                                                          region_bytes);
        if (rc) {
-               ecryptfs_printk(KERN_ERR, "prepare_write for "
+               if (rc == AOP_TRUNCATED_PAGE) {
+                       ecryptfs_release_lower_page(*lower_page, 0);
+                       goto retry;
+               } else {
+                       ecryptfs_printk(KERN_ERR, "prepare_write for "
                                "lower_page_index = [0x%.16x] failed; rc = "
                                "[%d]\n", lower_page_index, rc);
-       }
-out:
-       if (rc && (*lower_page)) {
-               if (rc == AOP_TRUNCATED_PAGE)
-                       ecryptfs_release_lower_page(*lower_page, 0);
-               else
                        ecryptfs_release_lower_page(*lower_page, 1);
-               (*lower_page) = NULL;
+                       (*lower_page) = NULL;
+               }
        }
+out:
        return rc;
 }