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    SubjectRe: [PATCH 1/2] ecryptfs: Improve metatdata read failure logging
    On 2012-01-11 18:00:41, Tim Gardner wrote:
    > There are 3 read failure cases in ecryptfs_read_metadata(), but only 2
    > of them are uniquely noted by kernel log messages. This patch
    > identifies and logs each read failure case. It also correctly interprets
    > a negative return value from ecryptfs_read_lower().

    I'm not sure that the negative return value was incorrectly interpreted.
    See below.

    >
    > Removes unnecessary variable initialization.
    >
    > Cc: linux-kernel@vger.kernel.org
    > Cc: stable@vger.kernel.org
    > Cc: Tyler Hicks <tyler.hicks@canonical.com>
    > Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
    > ---
    > fs/ecryptfs/crypto.c | 17 +++++++++++------
    > 1 files changed, 11 insertions(+), 6 deletions(-)
    >
    > diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
    > index d3c8776..ac063bd 100644
    > --- a/fs/ecryptfs/crypto.c
    > +++ b/fs/ecryptfs/crypto.c
    > @@ -1590,8 +1590,8 @@ int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
    > */
    > int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
    > {
    > - int rc = 0;
    > - char *page_virt = NULL;
    > + int rc;
    > + char *page_virt;
    > struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;
    > struct ecryptfs_crypt_stat *crypt_stat =
    > &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
    > @@ -1611,10 +1611,15 @@ int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
    > }
    > rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
    > ecryptfs_inode);
    > - if (rc >= 0)
    > - rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
    > - ecryptfs_dentry,
    > - ECRYPTFS_VALIDATE_HEADER_SIZE);
    > + if (rc < 0) {
    > + printk(KERN_ERR "%s: Could not read %u bytes\n",
    > + __func__, crypt_stat->extent_size);
    > + goto out;
    > + }

    This may break things a bit for users that use the
    ecryptfs_xattr_metadata mount option (which stores the metadata in an
    xattr, rather than the header of the file). A failure to read the lower
    file here doesn't matter because the metadata is likely stored in an
    xattr, which will be found with the ecryptfs_read_xattr_region() call
    below.

    I've never liked that ecryptfs potentially looks in both the header and
    the xattr for metadata, but that's how it has been since the very early
    days of eCryptfs. I've wanted to change this but there is the potential
    to break things for users who have a mixture of files with metadata in
    the header and in the header.

    Maybe we just go whole hog for 3.3 and only look in either the header or
    xattr for metadata, depending on whether or not ecryptfs_xattr_metadata
    is used?

    I could live with that, but I would definitely not want something like
    that to go to the stable kernel. Any thoughts?

    Tyler

    > +
    > + rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
    > + ecryptfs_dentry,
    > + ECRYPTFS_VALIDATE_HEADER_SIZE);
    > if (rc) {
    > memset(page_virt, 0, PAGE_CACHE_SIZE);
    > rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
    > --
    > 1.7.8.3
    >
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