Identity of an inode, which is defined by i_sb and i_ino or by individual
filesystem specific way, is not expected to be changed during inode's life
time. When identify an inode, taking i_lock _seems_ unnecessary. In source
code, we do have functions identifying an inode without i_lock held,
e.g. test_inode_iunique().

Then, fix those functions which take i_lock, e.g. find_inode_fast().

Note this change still put individual filesystem's test() method under
i_lock's protection. See next patch for more.

Signed-off-by: Guo Chao <y...@linux.vnet.ibm.com>
---
 fs/inode.c |   16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/fs/inode.c b/fs/inode.c
index 54e4b29..89d2bcc 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -786,11 +786,9 @@ static struct inode *find_inode(struct super_block *sb,
 
 repeat:
        hlist_for_each_entry(inode, node, head, i_hash) {
-               spin_lock(&inode->i_lock);
-               if (inode->i_sb != sb) {
-                       spin_unlock(&inode->i_lock);
+               if (inode->i_sb != sb)
                        continue;
-               }
+               spin_lock(&inode->i_lock);
                if (!test(inode, data)) {
                        spin_unlock(&inode->i_lock);
                        continue;
@@ -818,15 +816,11 @@ static struct inode *find_inode_fast(struct super_block 
*sb,
 
 repeat:
        hlist_for_each_entry(inode, node, head, i_hash) {
-               spin_lock(&inode->i_lock);
-               if (inode->i_ino != ino) {
-                       spin_unlock(&inode->i_lock);
+               if (inode->i_ino != ino)
                        continue;
-               }
-               if (inode->i_sb != sb) {
-                       spin_unlock(&inode->i_lock);
+               if (inode->i_sb != sb)
                        continue;
-               }
+               spin_lock(&inode->i_lock);
                if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
                        __wait_on_freeing_inode(inode);
                        goto repeat;
-- 
1.7.9.5

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