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Date: Tue, 29 Jul 2008 22:43:40 -0400
From: Erez Zadok <ezk@...sunysb.edu>
To: akpm@...ux-foundation.org
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
viro@...iv.linux.org.uk, hch@...radead.org, miklos@...redi.hu,
Erez Zadok <ezk@...sunysb.edu>
Subject: [PATCH 10/19] Unionfs: cache coherency fixes
Handle unhashed or silly-renamed lower dentries properly.
Signed-off-by: Erez Zadok <ezk@...sunysb.edu>
---
fs/unionfs/commonfops.c | 3 +-
fs/unionfs/debug.c | 2 +-
fs/unionfs/dentry.c | 49 +++++++++++++++++++++++++++++++++++++++++-----
fs/unionfs/main.c | 3 --
4 files changed, 46 insertions(+), 11 deletions(-)
diff --git a/fs/unionfs/commonfops.c b/fs/unionfs/commonfops.c
index df002d5..d64272b 100644
--- a/fs/unionfs/commonfops.c
+++ b/fs/unionfs/commonfops.c
@@ -466,7 +466,8 @@ reval_dentry:
dgen = atomic_read(&UNIONFS_D(dentry)->generation);
if (unlikely(sbgen > dgen)) {
- pr_debug("unionfs: retry (locked) dentry revalidation\n");
+ pr_debug("unionfs: retry (locked) dentry %s revalidation\n",
+ dentry->d_name.name);
schedule();
goto reval_dentry;
}
diff --git a/fs/unionfs/debug.c b/fs/unionfs/debug.c
index d154c32..4da4f0b 100644
--- a/fs/unionfs/debug.c
+++ b/fs/unionfs/debug.c
@@ -313,7 +313,7 @@ check_inode:
}
}
/* check if lower inode is newer than upper one (it shouldn't) */
- if (unlikely(is_newer_lower(dentry))) {
+ if (unlikely(is_newer_lower(dentry) && !is_negative_lower(dentry))) {
PRINT_CALLER(fname, fxn, line);
for (bindex = ibstart(inode); bindex <= ibend(inode);
bindex++) {
diff --git a/fs/unionfs/dentry.c b/fs/unionfs/dentry.c
index cd4611b..dfa4755 100644
--- a/fs/unionfs/dentry.c
+++ b/fs/unionfs/dentry.c
@@ -23,11 +23,16 @@ bool is_negative_lower(const struct dentry *dentry)
int bindex;
struct dentry *lower_dentry;
- BUG_ON(!dentry || dbstart(dentry) < 0);
+ BUG_ON(!dentry);
+ /* cache coherency: check if file was deleted on lower branch */
+ if (dbstart(dentry) < 0)
+ return true;
for (bindex = dbstart(dentry); bindex <= dbend(dentry); bindex++) {
lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
- /* XXX: what if lower_dentry is NULL? */
- if (lower_dentry && lower_dentry->d_inode)
+ /* unhashed (i.e., unlinked) lower dentries don't count */
+ if (lower_dentry && lower_dentry->d_inode &&
+ !d_deleted(lower_dentry) &&
+ !(lower_dentry->d_flags & DCACHE_NFSFS_RENAMED))
return false;
}
return true;
@@ -75,6 +80,7 @@ static bool __unionfs_d_revalidate_one(struct dentry *dentry,
verify_locked(dentry);
verify_locked(dentry->d_parent);
+ sbgen = atomic_read(&UNIONFS_SB(dentry->d_sb)->generation);
/* if the dentry is unhashed, do NOT revalidate */
if (d_deleted(dentry))
goto out;
@@ -83,7 +89,6 @@ static bool __unionfs_d_revalidate_one(struct dentry *dentry,
if (dentry->d_inode)
positive = 1;
dgen = atomic_read(&UNIONFS_D(dentry)->generation);
- sbgen = atomic_read(&UNIONFS_SB(dentry->d_sb)->generation);
/*
* If we are working on an unconnected dentry, then there is no
* revalidation to be done, because this file does not exist within
@@ -103,6 +108,21 @@ static bool __unionfs_d_revalidate_one(struct dentry *dentry,
/* Free the pointers for our inodes and this dentry. */
bstart = dbstart(dentry);
bend = dbend(dentry);
+
+ /*
+ * mntput unhashed lower dentries, because those files got
+ * deleted or rmdir'ed.
+ */
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
+ if (!lower_dentry)
+ continue;
+ if (!d_deleted(lower_dentry) &&
+ !(lower_dentry->d_flags & DCACHE_NFSFS_RENAMED))
+ continue;
+ unionfs_mntput(dentry, bindex);
+ }
+
__dput_lowers(dentry, bstart, bend);
dbstart(dentry) = dbend(dentry) = -1;
@@ -112,8 +132,12 @@ static bool __unionfs_d_revalidate_one(struct dentry *dentry,
iput_lowers_all(dentry->d_inode, true);
}
- result = unionfs_lookup_backend(dentry, &lowernd,
- interpose_flag);
+ if (realloc_dentry_private_data(dentry) != 0) {
+ valid = false;
+ goto out;
+ }
+
+ result = unionfs_lookup_full(dentry, &lowernd, interpose_flag);
if (result) {
if (IS_ERR(result)) {
valid = false;
@@ -179,6 +203,9 @@ static bool __unionfs_d_revalidate_one(struct dentry *dentry,
}
out:
+ if (valid)
+ atomic_set(&UNIONFS_D(dentry)->generation, sbgen);
+
return valid;
}
@@ -241,6 +268,16 @@ bool is_newer_lower(const struct dentry *dentry)
return true;
}
}
+
+ /*
+ * Last check: if this is a positive dentry, but somehow all lower
+ * dentries are negative or unhashed, then this dentry needs to be
+ * revalidated, because someone probably deleted the objects from
+ * the lower branches directly.
+ */
+ if (is_negative_lower(dentry))
+ return true;
+
return false; /* default: lower is not newer */
}
diff --git a/fs/unionfs/main.c b/fs/unionfs/main.c
index a9d2cb6..1fd67c6 100644
--- a/fs/unionfs/main.c
+++ b/fs/unionfs/main.c
@@ -88,9 +88,6 @@ struct dentry *unionfs_interpose(struct dentry *dentry, struct super_block *sb,
verify_locked(dentry);
- /* Make sure that we didn't get a negative dentry. */
- BUG_ON(is_negative_lower(dentry));
-
/*
* We allocate our new inode below by calling unionfs_iget,
* which will initialize some of the new inode's fields
--
1.5.2.2
--
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