ecryptfs: modify write path to encrypt page in writepage
Thieu Le [Wed, 9 Mar 2011 00:26:03 +0000 (16:26 -0800)]
Change the write path to encrypt the data only when the page is written to
disk in ecryptfs_writepage. Previously, ecryptfs encrypts the page in
ecryptfs_write_end which means that if there are multiple write requests to
the same page, ecryptfs ends up re-encrypting that page over and over again.
This patch minimizes the number of encryptions needed.

Signed-off-by: Thieu Le <thieule@chromium.org>
[tyhicks: Changed NULL .drop_inode sop pointer to generic_drop_inode]
Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>

fs/ecryptfs/ecryptfs_kernel.h
fs/ecryptfs/file.c
fs/ecryptfs/main.c
fs/ecryptfs/mmap.c
fs/ecryptfs/read_write.c
fs/ecryptfs/super.c

index 427478e..3ef5b00 100644 (file)
@@ -296,7 +296,6 @@ struct ecryptfs_inode_info {
        struct inode vfs_inode;
        struct inode *wii_inode;
        struct file *lower_file;
-       struct mutex lower_file_mutex;
        struct ecryptfs_crypt_stat crypt_stat;
 };
 
index 7d1050e..cedc913 100644 (file)
@@ -273,7 +273,14 @@ static int ecryptfs_release(struct inode *inode, struct file *file)
 static int
 ecryptfs_fsync(struct file *file, int datasync)
 {
-       return vfs_fsync(ecryptfs_file_to_lower(file), datasync);
+       int rc = 0;
+
+       rc = generic_file_fsync(file, datasync);
+       if (rc)
+               goto out;
+       rc = vfs_fsync(ecryptfs_file_to_lower(file), datasync);
+out:
+       return rc;
 }
 
 static int ecryptfs_fasync(int fd, struct file *file, int flag)
index 758323a..63e412c 100644 (file)
@@ -122,7 +122,6 @@ int ecryptfs_init_persistent_file(struct dentry *ecryptfs_dentry)
                ecryptfs_inode_to_private(ecryptfs_dentry->d_inode);
        int rc = 0;
 
-       mutex_lock(&inode_info->lower_file_mutex);
        if (!inode_info->lower_file) {
                struct dentry *lower_dentry;
                struct vfsmount *lower_mnt =
@@ -138,7 +137,6 @@ int ecryptfs_init_persistent_file(struct dentry *ecryptfs_dentry)
                        inode_info->lower_file = NULL;
                }
        }
-       mutex_unlock(&inode_info->lower_file_mutex);
        return rc;
 }
 
index 519af27..5e15013 100644 (file)
@@ -62,6 +62,18 @@ static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
 {
        int rc;
 
+       /*
+        * Refuse to write the page out if we are called from reclaim context
+        * since our writepage() path may potentially allocate memory when
+        * calling into the lower fs vfs_write() which may in turn invoke
+        * us again.
+        */
+       if (current->flags & PF_MEMALLOC) {
+               redirty_page_for_writepage(wbc, page);
+               rc = 0;
+               goto out;
+       }
+
        rc = ecryptfs_encrypt_page(page);
        if (rc) {
                ecryptfs_printk(KERN_WARNING, "Error encrypting "
@@ -70,8 +82,8 @@ static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
                goto out;
        }
        SetPageUptodate(page);
-       unlock_page(page);
 out:
+       unlock_page(page);
        return rc;
 }
 
@@ -481,6 +493,7 @@ static int ecryptfs_write_end(struct file *file,
        struct ecryptfs_crypt_stat *crypt_stat =
                &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
        int rc;
+       int need_unlock_page = 1;
 
        ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
                        "(page w/ index = [0x%.16lx], to = [%d])\n", index, to);
@@ -501,26 +514,26 @@ static int ecryptfs_write_end(struct file *file,
                        "zeros in page with index = [0x%.16lx]\n", index);
                goto out;
        }
-       rc = ecryptfs_encrypt_page(page);
-       if (rc) {
-               ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
-                               "index [0x%.16lx])\n", index);
-               goto out;
-       }
+       set_page_dirty(page);
+       unlock_page(page);
+       need_unlock_page = 0;
        if (pos + copied > i_size_read(ecryptfs_inode)) {
                i_size_write(ecryptfs_inode, pos + copied);
                ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
                        "[0x%.16llx]\n",
                        (unsigned long long)i_size_read(ecryptfs_inode));
+               balance_dirty_pages_ratelimited(mapping);
+               rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode);
+               if (rc) {
+                       printk(KERN_ERR "Error writing inode size to metadata; "
+                              "rc = [%d]\n", rc);
+                       goto out;
+               }
        }
-       rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode);
-       if (rc)
-               printk(KERN_ERR "Error writing inode size to metadata; "
-                      "rc = [%d]\n", rc);
-       else
-               rc = copied;
+       rc = copied;
 out:
-       unlock_page(page);
+       if (need_unlock_page)
+               unlock_page(page);
        page_cache_release(page);
        return rc;
 }
index db184ef..85d4309 100644 (file)
@@ -44,15 +44,11 @@ int ecryptfs_write_lower(struct inode *ecryptfs_inode, char *data,
        ssize_t rc;
 
        inode_info = ecryptfs_inode_to_private(ecryptfs_inode);
-       mutex_lock(&inode_info->lower_file_mutex);
        BUG_ON(!inode_info->lower_file);
-       inode_info->lower_file->f_pos = offset;
        fs_save = get_fs();
        set_fs(get_ds());
-       rc = vfs_write(inode_info->lower_file, data, size,
-                      &inode_info->lower_file->f_pos);
+       rc = vfs_write(inode_info->lower_file, data, size, &offset);
        set_fs(fs_save);
-       mutex_unlock(&inode_info->lower_file_mutex);
        mark_inode_dirty_sync(ecryptfs_inode);
        return rc;
 }
@@ -234,15 +230,11 @@ int ecryptfs_read_lower(char *data, loff_t offset, size_t size,
        mm_segment_t fs_save;
        ssize_t rc;
 
-       mutex_lock(&inode_info->lower_file_mutex);
        BUG_ON(!inode_info->lower_file);
-       inode_info->lower_file->f_pos = offset;
        fs_save = get_fs();
        set_fs(get_ds());
-       rc = vfs_read(inode_info->lower_file, data, size,
-                     &inode_info->lower_file->f_pos);
+       rc = vfs_read(inode_info->lower_file, data, size, &offset);
        set_fs(fs_save);
-       mutex_unlock(&inode_info->lower_file_mutex);
        return rc;
 }
 
index 3042fe1..bacc882 100644 (file)
@@ -55,7 +55,6 @@ static struct inode *ecryptfs_alloc_inode(struct super_block *sb)
        if (unlikely(!inode_info))
                goto out;
        ecryptfs_init_crypt_stat(&inode_info->crypt_stat);
-       mutex_init(&inode_info->lower_file_mutex);
        inode_info->lower_file = NULL;
        inode = &inode_info->vfs_inode;
 out:
@@ -198,7 +197,7 @@ static int ecryptfs_show_options(struct seq_file *m, struct vfsmount *mnt)
 const struct super_operations ecryptfs_sops = {
        .alloc_inode = ecryptfs_alloc_inode,
        .destroy_inode = ecryptfs_destroy_inode,
-       .drop_inode = generic_delete_inode,
+       .drop_inode = generic_drop_inode,
        .statfs = ecryptfs_statfs,
        .remount_fs = NULL,
        .evict_inode = ecryptfs_evict_inode,