ocfs2: Remove i_generation from inode lock names
OCFS2 puts inode meta data in the "lock value block" provided by the DLM.
Typically, i_generation is encoded in the lock name so that a deleted inode
on and a new one in the same block don't share the same lvb.
Unfortunately, that scheme means that the read in ocfs2_read_locked_inode()
is potentially thrown away as soon as the meta data lock is taken - we
cannot encode the lock name without first knowing i_generation, which
requires a disk read.
This patch encodes i_generation in the inode meta data lvb, and removes the
value from the inode meta data lock name. This way, the read can be covered
by a lock, and at the same time we can distinguish between an up to date and
a stale LVB.
This will help cold-cache stat(2) performance in particular.
Since this patch changes the protocol version, we take the opportunity to do
a minor re-organization of two of the LVB fields.
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index 66ca7a8..69d3db5 100644
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -54,8 +54,6 @@
#include "buffer_head_io.h"
-#define OCFS2_FI_FLAG_NOWAIT 0x1
-#define OCFS2_FI_FLAG_DELETE 0x2
struct ocfs2_find_inode_args
{
u64 fi_blkno;
@@ -109,7 +107,7 @@
return ilookup5(osb->sb, args.fi_ino, ocfs2_find_actor, &args);
}
-struct inode *ocfs2_iget(struct ocfs2_super *osb, u64 blkno)
+struct inode *ocfs2_iget(struct ocfs2_super *osb, u64 blkno, int flags)
{
struct inode *inode = NULL;
struct super_block *sb = osb->sb;
@@ -127,7 +125,7 @@
}
args.fi_blkno = blkno;
- args.fi_flags = 0;
+ args.fi_flags = flags;
args.fi_ino = ino_from_blkno(sb, blkno);
inode = iget5_locked(sb, args.fi_ino, ocfs2_find_actor,
@@ -297,15 +295,11 @@
OCFS2_I(inode)->ip_orphaned_slot = OCFS2_INVALID_SLOT;
OCFS2_I(inode)->ip_attr = le32_to_cpu(fe->i_attr);
- if (create_ino)
- inode->i_ino = ino_from_blkno(inode->i_sb,
- le64_to_cpu(fe->i_blkno));
-
- mlog(0, "blkno = %llu, ino = %lu, create_ino = %s\n",
- (unsigned long long)fe->i_blkno, inode->i_ino, create_ino ? "true" : "false");
-
inode->i_nlink = le16_to_cpu(fe->i_links_count);
+ if (fe->i_flags & cpu_to_le32(OCFS2_SYSTEM_FL))
+ OCFS2_I(inode)->ip_flags |= OCFS2_INODE_SYSTEM_FILE;
+
if (fe->i_flags & cpu_to_le32(OCFS2_LOCAL_ALLOC_FL)) {
OCFS2_I(inode)->ip_flags |= OCFS2_INODE_BITMAP;
mlog(0, "local alloc inode: i_ino=%lu\n", inode->i_ino);
@@ -343,12 +337,28 @@
break;
}
+ if (create_ino) {
+ inode->i_ino = ino_from_blkno(inode->i_sb,
+ le64_to_cpu(fe->i_blkno));
+
+ /*
+ * If we ever want to create system files from kernel,
+ * the generation argument to
+ * ocfs2_inode_lock_res_init() will have to change.
+ */
+ BUG_ON(fe->i_flags & cpu_to_le32(OCFS2_SYSTEM_FL));
+
+ ocfs2_inode_lock_res_init(&OCFS2_I(inode)->ip_meta_lockres,
+ OCFS2_LOCK_TYPE_META, 0, inode);
+ }
+
ocfs2_inode_lock_res_init(&OCFS2_I(inode)->ip_rw_lockres,
- OCFS2_LOCK_TYPE_RW, inode);
- ocfs2_inode_lock_res_init(&OCFS2_I(inode)->ip_meta_lockres,
- OCFS2_LOCK_TYPE_META, inode);
+ OCFS2_LOCK_TYPE_RW, inode->i_generation,
+ inode);
+
ocfs2_inode_lock_res_init(&OCFS2_I(inode)->ip_data_lockres,
- OCFS2_LOCK_TYPE_DATA, inode);
+ OCFS2_LOCK_TYPE_DATA, inode->i_generation,
+ inode);
ocfs2_set_inode_flags(inode);
inode->i_flags |= S_NOATIME;
@@ -366,15 +376,15 @@
struct ocfs2_super *osb;
struct ocfs2_dinode *fe;
struct buffer_head *bh = NULL;
- int status;
- int sysfile = 0;
+ int status, can_lock;
+ u32 generation = 0;
mlog_entry("(0x%p, 0x%p)\n", inode, args);
status = -EINVAL;
if (inode == NULL || inode->i_sb == NULL) {
mlog(ML_ERROR, "bad inode\n");
- goto bail;
+ return status;
}
sb = inode->i_sb;
osb = OCFS2_SB(sb);
@@ -382,50 +392,110 @@
if (!args) {
mlog(ML_ERROR, "bad inode args\n");
make_bad_inode(inode);
- goto bail;
+ return status;
}
- /* Read the FE off disk. This is safe because the kernel only
- * does one read_inode2 for a new inode, and if it doesn't
- * exist yet then nobody can be working on it! */
- status = ocfs2_read_block(osb, args->fi_blkno, &bh, 0, NULL);
+ /*
+ * To improve performance of cold-cache inode stats, we take
+ * the cluster lock here if possible.
+ *
+ * Generally, OCFS2 never trusts the contents of an inode
+ * unless it's holding a cluster lock, so taking it here isn't
+ * a correctness issue as much as it is a performance
+ * improvement.
+ *
+ * There are three times when taking the lock is not a good idea:
+ *
+ * 1) During startup, before we have initialized the DLM.
+ *
+ * 2) If we are reading certain system files which never get
+ * cluster locks (local alloc, truncate log).
+ *
+ * 3) If the process doing the iget() is responsible for
+ * orphan dir recovery. We're holding the orphan dir lock and
+ * can get into a deadlock with another process on another
+ * node in ->delete_inode().
+ *
+ * #1 and #2 can be simply solved by never taking the lock
+ * here for system files (which are the only type we read
+ * during mount). It's a heavier approach, but our main
+ * concern is user-accesible files anyway.
+ *
+ * #3 works itself out because we'll eventually take the
+ * cluster lock before trusting anything anyway.
+ */
+ can_lock = !(args->fi_flags & OCFS2_FI_FLAG_SYSFILE)
+ && !(args->fi_flags & OCFS2_FI_FLAG_NOLOCK);
+
+ /*
+ * To maintain backwards compatibility with older versions of
+ * ocfs2-tools, we still store the generation value for system
+ * files. The only ones that actually matter to userspace are
+ * the journals, but it's easier and inexpensive to just flag
+ * all system files similarly.
+ */
+ if (args->fi_flags & OCFS2_FI_FLAG_SYSFILE)
+ generation = osb->fs_generation;
+
+ ocfs2_inode_lock_res_init(&OCFS2_I(inode)->ip_meta_lockres,
+ OCFS2_LOCK_TYPE_META,
+ generation, inode);
+
+ if (can_lock) {
+ status = ocfs2_meta_lock(inode, NULL, NULL, 0);
+ if (status) {
+ make_bad_inode(inode);
+ mlog_errno(status);
+ return status;
+ }
+ }
+
+ status = ocfs2_read_block(osb, args->fi_blkno, &bh, 0,
+ can_lock ? inode : NULL);
if (status < 0) {
mlog_errno(status);
- make_bad_inode(inode);
goto bail;
}
+ status = -EINVAL;
fe = (struct ocfs2_dinode *) bh->b_data;
if (!OCFS2_IS_VALID_DINODE(fe)) {
mlog(ML_ERROR, "Invalid dinode #%llu: signature = %.*s\n",
(unsigned long long)fe->i_blkno, 7, fe->i_signature);
- make_bad_inode(inode);
goto bail;
}
- if (fe->i_flags & cpu_to_le32(OCFS2_SYSTEM_FL))
- sysfile = 1;
+ /*
+ * This is a code bug. Right now the caller needs to
+ * understand whether it is asking for a system file inode or
+ * not so the proper lock names can be built.
+ */
+ mlog_bug_on_msg(!!(fe->i_flags & cpu_to_le32(OCFS2_SYSTEM_FL)) !=
+ !!(args->fi_flags & OCFS2_FI_FLAG_SYSFILE),
+ "Inode %llu: system file state is ambigous\n",
+ (unsigned long long)args->fi_blkno);
if (S_ISCHR(le16_to_cpu(fe->i_mode)) ||
S_ISBLK(le16_to_cpu(fe->i_mode)))
inode->i_rdev = huge_decode_dev(le64_to_cpu(fe->id1.dev1.i_rdev));
- status = -EINVAL;
if (ocfs2_populate_inode(inode, fe, 0) < 0) {
mlog(ML_ERROR, "populate failed! i_blkno=%llu, i_ino=%lu\n",
(unsigned long long)fe->i_blkno, inode->i_ino);
- make_bad_inode(inode);
goto bail;
}
BUG_ON(args->fi_blkno != le64_to_cpu(fe->i_blkno));
- if (sysfile)
- OCFS2_I(inode)->ip_flags |= OCFS2_INODE_SYSTEM_FILE;
-
status = 0;
bail:
+ if (can_lock)
+ ocfs2_meta_unlock(inode, 0);
+
+ if (status < 0)
+ make_bad_inode(inode);
+
if (args && bh)
brelse(bh);
@@ -898,9 +968,15 @@
goto bail_unlock_inode;
}
- /* Mark the inode as successfully deleted. This is important
- * for ocfs2_clear_inode as it will check this flag and skip
- * any checkpointing work */
+ /*
+ * Mark the inode as successfully deleted.
+ *
+ * This is important for ocfs2_clear_inode() as it will check
+ * this flag and skip any checkpointing work
+ *
+ * ocfs2_stuff_meta_lvb() also uses this flag to invalidate
+ * the LVB for other nodes.
+ */
OCFS2_I(inode)->ip_flags |= OCFS2_INODE_DELETED;
bail_unlock_inode: