ecryptfs: modify write path to encrypt page in writepage

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>

6 files changed, 38 insertions, 30 deletions

diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index 427478e29760..3ef5b0030231 100644
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -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;
 };
 
diff --git a/fs/ecryptfs/file.c b/fs/ecryptfs/file.c
index 7d1050e254f9..cedc913d11ba 100644
--- a/fs/ecryptfs/file.c
+++ b/fs/ecryptfs/file.c
@@ -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)
diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
index 758323a0f09a..63e412cf0fa1 100644
--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -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;
 }
 
diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c
index 519af27db059..5e150131eb9d 100644
--- a/fs/ecryptfs/mmap.c
+++ b/fs/ecryptfs/mmap.c
@@ -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;
 }
diff --git a/fs/ecryptfs/read_write.c b/fs/ecryptfs/read_write.c
index db184ef15d3d..85d430963116 100644
--- a/fs/ecryptfs/read_write.c
+++ b/fs/ecryptfs/read_write.c
@@ -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;
 }
 
diff --git a/fs/ecryptfs/super.c b/fs/ecryptfs/super.c
index 3042fe123a34..bacc882e1ae4 100644
--- a/fs/ecryptfs/super.c
+++ b/fs/ecryptfs/super.c
@@ -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,