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Subject[PATCH 2/3] reiserfs: Don't lock journal_init()
Date
journal_init() doesn't need the lock since no operation
on the filesystem is involved there. journal_read() and
get_list_bitmap() have yet to be reviewed carefully though
before removing the lock there. Just keep the it around these
two calls for safety.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jeff Mahoney <jeffm@suse.com>
---
fs/reiserfs/journal.c | 53 ++++++++++++++++++------------------------------
fs/reiserfs/super.c | 21 ++++++++++---------
2 files changed, 31 insertions(+), 43 deletions(-)
diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c
index eb71106..728fb3fd 100644
--- a/fs/reiserfs/journal.c
+++ b/fs/reiserfs/journal.c
@@ -2678,16 +2678,10 @@ int journal_init(struct super_block *sb, const char *j_dev_name,
char b[BDEVNAME_SIZE];
int ret;

- /*
- * Unlock here to avoid various RECLAIM-FS-ON <-> IN-RECLAIM-FS
- * dependency inversion warnings.
- */
- reiserfs_write_unlock(sb);
journal = SB_JOURNAL(sb) = vzalloc(sizeof(struct reiserfs_journal));
if (!journal) {
reiserfs_warning(sb, "journal-1256",
"unable to get memory for journal structure");
- reiserfs_write_lock(sb);
return 1;
}
INIT_LIST_HEAD(&journal->j_bitmap_nodes);
@@ -2695,10 +2689,8 @@ int journal_init(struct super_block *sb, const char *j_dev_name,
INIT_LIST_HEAD(&journal->j_working_list);
INIT_LIST_HEAD(&journal->j_journal_list);
journal->j_persistent_trans = 0;
- ret = reiserfs_allocate_list_bitmaps(sb, journal->j_list_bitmap,
- reiserfs_bmap_count(sb));
- reiserfs_write_lock(sb);
- if (ret)
+ if (reiserfs_allocate_list_bitmaps(sb, journal->j_list_bitmap,
+ reiserfs_bmap_count(sb)))
goto free_and_return;

allocate_bitmap_nodes(sb);
@@ -2727,27 +2719,11 @@ int journal_init(struct super_block *sb, const char *j_dev_name,
goto free_and_return;
}

- /*
- * We need to unlock here to avoid creating the following
- * dependency:
- * reiserfs_lock -> sysfs_mutex
- * Because the reiserfs mmap path creates the following dependency:
- * mm->mmap -> reiserfs_lock, hence we have
- * mm->mmap -> reiserfs_lock ->sysfs_mutex
- * This would ends up in a circular dependency with sysfs readdir path
- * which does sysfs_mutex -> mm->mmap_sem
- * This is fine because the reiserfs lock is useless in mount path,
- * at least until we call journal_begin. We keep it for paranoid
- * reasons.
- */
- reiserfs_write_unlock(sb);
if (journal_init_dev(sb, journal, j_dev_name) != 0) {
- reiserfs_write_lock(sb);
reiserfs_warning(sb, "sh-462",
"unable to initialize jornal device");
goto free_and_return;
}
- reiserfs_write_lock(sb);

rs = SB_DISK_SUPER_BLOCK(sb);

@@ -2829,9 +2805,7 @@ int journal_init(struct super_block *sb, const char *j_dev_name,
journal->j_mount_id = 10;
journal->j_state = 0;
atomic_set(&(journal->j_jlock), 0);
- reiserfs_write_unlock(sb);
journal->j_cnode_free_list = allocate_cnodes(num_cnodes);
- reiserfs_write_lock(sb);
journal->j_cnode_free_orig = journal->j_cnode_free_list;
journal->j_cnode_free = journal->j_cnode_free_list ? num_cnodes : 0;
journal->j_cnode_used = 0;
@@ -2848,24 +2822,37 @@ int journal_init(struct super_block *sb, const char *j_dev_name,

init_journal_hash(sb);
jl = journal->j_current_jl;
+
+ /*
+ * get_list_bitmap() may call flush_commit_list() which
+ * requires the lock. Calling flush_commit_list() shouldn't happen
+ * this early but I like to be paranoid.
+ */
+ reiserfs_write_lock(sb);
jl->j_list_bitmap = get_list_bitmap(sb, jl);
+ reiserfs_write_unlock(sb);
if (!jl->j_list_bitmap) {
reiserfs_warning(sb, "journal-2005",
"get_list_bitmap failed for journal list 0");
goto free_and_return;
}
- if (journal_read(sb) < 0) {
+
+ /*
+ * Journal_read needs to be inspected in order to push down
+ * the lock further inside (or even remove it).
+ */
+ reiserfs_write_lock(sb);
+ ret = journal_read(sb);
+ reiserfs_write_unlock(sb);
+ if (ret < 0) {
reiserfs_warning(sb, "reiserfs-2006",
"Replay Failure, unable to mount");
goto free_and_return;
}

reiserfs_mounted_fs_count++;
- if (reiserfs_mounted_fs_count <= 1) {
- reiserfs_write_unlock(sb);
+ if (reiserfs_mounted_fs_count <= 1)
commit_wq = alloc_workqueue("reiserfs", WQ_MEM_RECLAIM, 0);
- reiserfs_write_lock(sb);
- }

INIT_DELAYED_WORK(&journal->j_work, flush_async_commits);
journal->j_work_sb = sb;
diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
index 1f0d4fa..b5f167c 100644
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -1727,6 +1727,17 @@ static int reiserfs_fill_super(struct super_block *s, void *data, int silent)
printk("reiserfs: using flush barriers\n");
}

+ // set_device_ro(s->s_dev, 1) ;
+ if (journal_init(s, jdev_name, old_format, commit_max_age)) {
+ SWARN(silent, s, "sh-2022",
+ "unable to initialize journal space");
+ goto error_unlocked;
+ } else {
+ jinit_done = 1; /* once this is set, journal_release must be called
+ ** if we error out of the mount
+ */
+ }
+
/*
* This path assumed to be called with the BKL in the old times.
* Now we have inherited the big reiserfs lock from it and many
@@ -1737,16 +1748,6 @@ static int reiserfs_fill_super(struct super_block *s, void *data, int silent)
*/
reiserfs_write_lock(s);

- // set_device_ro(s->s_dev, 1) ;
- if (journal_init(s, jdev_name, old_format, commit_max_age)) {
- SWARN(silent, s, "sh-2022",
- "unable to initialize journal space");
- goto error;
- } else {
- jinit_done = 1; /* once this is set, journal_release must be called
- ** if we error out of the mount
- */
- }
if (reread_meta_blocks(s)) {
SWARN(silent, s, "jmacd-9",
"unable to reread meta blocks after journal init");
--
1.7.5.4


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