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Subject[PATCH] ecryptfs: modify write path to encrypt page in writepage
Date
Hi Tyler,

Sorry for the delay, got sidetracked with some other work. I've addressed the
dd hang and the low memory condition as discussed in IRC.

PTAL.

Thanks,
Thieu

---
fs/ecryptfs/ecryptfs_kernel.h | 1 -
fs/ecryptfs/file.c | 9 +++++++-
fs/ecryptfs/main.c | 2 -
fs/ecryptfs/mmap.c | 46 ++++++++++++++++++++++++++++------------
fs/ecryptfs/read_write.c | 12 +---------
fs/ecryptfs/super.c | 1 -
6 files changed, 42 insertions(+), 29 deletions(-)
diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index dbc84ed..13517ac 100644
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -297,7 +297,6 @@ 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 81e10e6..9f7ce63 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 758323a..63e412c 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 cc64fca..d375210 100644
--- a/fs/ecryptfs/mmap.c
+++ b/fs/ecryptfs/mmap.c
@@ -62,6 +62,23 @@ 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.
+ *
+ * This avoids stack overflows when called from deeply used stacks in
+ * random callers for direct reclaim or memcg reclaim. We explicitly
+ * allow reclaim from kswapd as the stack usage there is relatively low.
+ *
+ * This should really be done by the core VM, but until that happens
+ * filesystems like XFS, btrfs and ext4 have to take care of this
+ * by themselves.
+ */
+ if ((current->flags & (PF_MEMALLOC|PF_KSWAPD)) == 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 +87,8 @@ static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
goto out;
}
SetPageUptodate(page);
- unlock_page(page);
out:
+ unlock_page(page);
return rc;
}

@@ -486,6 +503,7 @@ 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;

if (crypt_stat->flags & ECRYPTFS_NEW_FILE) {
ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in "
@@ -512,26 +530,26 @@ 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 db184ef..85d4309 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 3042fe1..15c969e 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:
--
1.7.3.1


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