[PATCH] eCryptfs: resolve lower page unlocking problem

eCryptfs lower file handling code has several issues:
  - Retval from prepare_write()/commit_write() wasn't checked to equality
    to AOP_TRUNCATED_PAGE.
  - In some places page wasn't unmapped and unlocked after error.

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/mmap.c b/fs/ecryptfs/mmap.c
index 3a6f65c..82bdbed 100644 (file)
--- a/fs/ecryptfs/mmap.c
+++ b/fs/ecryptfs/mmap.c
@@ -422,9 +422,11 @@ out:
        return rc;
 }
 
-static void ecryptfs_release_lower_page(struct page *lower_page)
+static
+void ecryptfs_release_lower_page(struct page *lower_page, int page_locked)
 {
-       unlock_page(lower_page);
+       if (page_locked)
+               unlock_page(lower_page);
        page_cache_release(lower_page);
 }
 
@@ -454,6 +456,13 @@ 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)
+                       ecryptfs_release_lower_page(header_page, 0);
+               else
+                       ecryptfs_release_lower_page(header_page, 1);
+               goto out;
+       }
        file_size = (u64)i_size_read(inode);
        ecryptfs_printk(KERN_DEBUG, "Writing size: [0x%.16x]\n", file_size);
        file_size = cpu_to_be64(file_size);
@@ -465,7 +474,10 @@ 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");
-       ecryptfs_release_lower_page(header_page);
+       if (rc == AOP_TRUNCATED_PAGE)
+               ecryptfs_release_lower_page(header_page, 0);
+       else
+               ecryptfs_release_lower_page(header_page, 1);
        lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
        mark_inode_dirty_sync(inode);
 out:
@@ -572,7 +584,10 @@ int ecryptfs_get_lower_page(struct page **lower_page, struct inode *lower_inode,
        }
 out:
        if (rc && (*lower_page)) {
-               ecryptfs_release_lower_page(*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;
        }
        return rc;
@@ -588,16 +603,19 @@ ecryptfs_commit_lower_page(struct page *lower_page, struct inode *lower_inode,
                           struct file *lower_file, int byte_offset,
                           int region_size)
 {
+       int page_locked = 1;
        int rc = 0;
 
        rc = lower_inode->i_mapping->a_ops->commit_write(
                lower_file, lower_page, byte_offset, region_size);
+       if (rc == AOP_TRUNCATED_PAGE)
+               page_locked = 0;
        if (rc < 0) {
                ecryptfs_printk(KERN_ERR,
                                "Error committing write; rc = [%d]\n", rc);
        } else
                rc = 0;
-       ecryptfs_release_lower_page(lower_page);
+       ecryptfs_release_lower_page(lower_page, page_locked);
        return rc;
 }