[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>

1 files changed, 16 insertions, 12 deletions

diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c
index 7def4be83e61..b731b09499cb 100644
--- 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;
 }