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author | Miklos Szeredi <miklos@szeredi.hu> | 2016-03-26 21:14:37 +0100 |
---|---|---|
committer | Theodore Ts'o <tytso@mit.edu> | 2016-03-26 21:14:37 +0100 |
commit | d101a125954eae1d397adda94ca6319485a50493 (patch) | |
tree | 0f5853af51446f389c60f1a25f3875ef8a75ba41 /fs | |
parent | ext4 crypto: don't let data integrity writebacks fail with ENOMEM (diff) | |
download | linux-d101a125954eae1d397adda94ca6319485a50493.tar.xz linux-d101a125954eae1d397adda94ca6319485a50493.zip |
fs: add file_dentry()
This series fixes bugs in nfs and ext4 due to 4bacc9c9234c ("overlayfs:
Make f_path always point to the overlay and f_inode to the underlay").
Regular files opened on overlayfs will result in the file being opened on
the underlying filesystem, while f_path points to the overlayfs
mount/dentry.
This confuses filesystems which get the dentry from struct file and assume
it's theirs.
Add a new helper, file_dentry() [*], to get the filesystem's own dentry
from the file. This checks file->f_path.dentry->d_flags against
DCACHE_OP_REAL, and returns file->f_path.dentry if DCACHE_OP_REAL is not
set (this is the common, non-overlayfs case).
In the uncommon case it will call into overlayfs's ->d_real() to get the
underlying dentry, matching file_inode(file).
The reason we need to check against the inode is that if the file is copied
up while being open, d_real() would return the upper dentry, while the open
file comes from the lower dentry.
[*] If possible, it's better simply to use file_inode() instead.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Tested-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: <stable@vger.kernel.org> # v4.2
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Daniel Axtens <dja@axtens.net>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/dcache.c | 5 | ||||
-rw-r--r-- | fs/overlayfs/super.c | 33 |
2 files changed, 37 insertions, 1 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index 32ceae3e6112..d5ecc6e477da 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1667,7 +1667,8 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE | DCACHE_OP_DELETE | - DCACHE_OP_SELECT_INODE)); + DCACHE_OP_SELECT_INODE | + DCACHE_OP_REAL)); dentry->d_op = op; if (!op) return; @@ -1685,6 +1686,8 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) dentry->d_flags |= DCACHE_OP_PRUNE; if (op->d_select_inode) dentry->d_flags |= DCACHE_OP_SELECT_INODE; + if (op->d_real) + dentry->d_flags |= DCACHE_OP_REAL; } EXPORT_SYMBOL(d_set_d_op); diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index ef64984c9bbc..5d972e6cd3fe 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -295,6 +295,37 @@ static void ovl_dentry_release(struct dentry *dentry) } } +static struct dentry *ovl_d_real(struct dentry *dentry, struct inode *inode) +{ + struct dentry *real; + + if (d_is_dir(dentry)) { + if (!inode || inode == d_inode(dentry)) + return dentry; + goto bug; + } + + real = ovl_dentry_upper(dentry); + if (real && (!inode || inode == d_inode(real))) + return real; + + real = ovl_dentry_lower(dentry); + if (!real) + goto bug; + + if (!inode || inode == d_inode(real)) + return real; + + /* Handle recursion */ + if (real->d_flags & DCACHE_OP_REAL) + return real->d_op->d_real(real, inode); + +bug: + WARN(1, "ovl_d_real(%pd4, %s:%lu\n): real dentry not found\n", dentry, + inode ? inode->i_sb->s_id : "NULL", inode ? inode->i_ino : 0); + return dentry; +} + static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags) { struct ovl_entry *oe = dentry->d_fsdata; @@ -339,11 +370,13 @@ static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags) static const struct dentry_operations ovl_dentry_operations = { .d_release = ovl_dentry_release, .d_select_inode = ovl_d_select_inode, + .d_real = ovl_d_real, }; static const struct dentry_operations ovl_reval_dentry_operations = { .d_release = ovl_dentry_release, .d_select_inode = ovl_d_select_inode, + .d_real = ovl_d_real, .d_revalidate = ovl_dentry_revalidate, .d_weak_revalidate = ovl_dentry_weak_revalidate, }; |