Btrfs: add a delalloc mutex to inodes for delalloc reservations

I was using i_mutex for this, but we're getting bogus lockdep warnings by doing
that and theres no real way to get rid of those, so just stop using i_mutex to
protect delalloc metadata reservations and use a delalloc mutex instead.  This
shouldn't be contended often at all, only if you are writing and mmap writing to
the file at the same time.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 634608d..9b9b15f 100644 (file)
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -51,6 +51,9 @@ struct btrfs_inode {
        /* held while logging the inode in tree-log.c */
        struct mutex log_mutex;
 
+       /* held while doing delalloc reservations */
+       struct mutex delalloc_mutex;
+
        /* used to order data wrt metadata */
        struct btrfs_ordered_inode_tree ordered_tree;
 

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 556f9aa..e0ad5f0 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4345,12 +4345,11 @@ int btrfs_delalloc_reserve_metadata(struct inode *inode, u64 num_bytes)
        /* Need to be holding the i_mutex here if we aren't free space cache */
        if (btrfs_is_free_space_inode(root, inode))
                flush = 0;
-       else
-               WARN_ON(!mutex_is_locked(&inode->i_mutex));
 
        if (flush && btrfs_transaction_in_commit(root->fs_info))
                schedule_timeout(1);
 
+       mutex_lock(&BTRFS_I(inode)->delalloc_mutex);
        num_bytes = ALIGN(num_bytes, root->sectorsize);
 
        spin_lock(&BTRFS_I(inode)->lock);
@@ -4405,6 +4404,7 @@ int btrfs_delalloc_reserve_metadata(struct inode *inode, u64 num_bytes)
                                                      btrfs_ino(inode),
                                                      to_free, 0);
                }
+               mutex_unlock(&BTRFS_I(inode)->delalloc_mutex);
                return ret;
        }
 
@@ -4415,6 +4415,7 @@ int btrfs_delalloc_reserve_metadata(struct inode *inode, u64 num_bytes)
        }
        BTRFS_I(inode)->reserved_extents += nr_extents;
        spin_unlock(&BTRFS_I(inode)->lock);
+       mutex_unlock(&BTRFS_I(inode)->delalloc_mutex);
 
        if (to_reserve)
                trace_btrfs_space_reservation(root->fs_info,"delalloc",

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 619742d..5977987 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2239,14 +2239,7 @@ int btrfs_orphan_cleanup(struct btrfs_root *root)
                                continue;
                        }
                        nr_truncate++;
-                       /*
-                        * Need to hold the imutex for reservation purposes, not
-                        * a huge deal here but I have a WARN_ON in
-                        * btrfs_delalloc_reserve_space to catch offenders.
-                        */
-                       mutex_lock(&inode->i_mutex);
                        ret = btrfs_truncate(inode);
-                       mutex_unlock(&inode->i_mutex);
                } else {
                        nr_unlink++;
                }
@@ -6411,10 +6404,7 @@ int btrfs_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
        u64 page_start;
        u64 page_end;
 
-       /* Need this to keep space reservations serialized */
-       mutex_lock(&inode->i_mutex);
        ret  = btrfs_delalloc_reserve_space(inode, PAGE_CACHE_SIZE);
-       mutex_unlock(&inode->i_mutex);
        if (!ret)
                ret = btrfs_update_time(vma->vm_file);
        if (ret) {
@@ -6758,6 +6748,7 @@ struct inode *btrfs_alloc_inode(struct super_block *sb)
        extent_io_tree_init(&ei->io_tree, &inode->i_data);
        extent_io_tree_init(&ei->io_failure_tree, &inode->i_data);
        mutex_init(&ei->log_mutex);
+       mutex_init(&ei->delalloc_mutex);
        btrfs_ordered_inode_tree_init(&ei->ordered_tree);
        INIT_LIST_HEAD(&ei->i_orphan);
        INIT_LIST_HEAD(&ei->delalloc_inodes);

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 7fdf22c..6834be4 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -868,10 +868,8 @@ static int cluster_pages_for_defrag(struct inode *inode,
                return 0;
        file_end = (isize - 1) >> PAGE_CACHE_SHIFT;
 
-       mutex_lock(&inode->i_mutex);
        ret = btrfs_delalloc_reserve_space(inode,
                                           num_pages << PAGE_CACHE_SHIFT);
-       mutex_unlock(&inode->i_mutex);
        if (ret)
                return ret;
 again:

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index efe9f79..8c1aae2 100644 (file)
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -2949,9 +2949,7 @@ static int relocate_file_extent_cluster(struct inode *inode,
        index = (cluster->start - offset) >> PAGE_CACHE_SHIFT;
        last_index = (cluster->end - offset) >> PAGE_CACHE_SHIFT;
        while (index <= last_index) {
-               mutex_lock(&inode->i_mutex);
                ret = btrfs_delalloc_reserve_metadata(inode, PAGE_CACHE_SIZE);
-               mutex_unlock(&inode->i_mutex);
                if (ret)
                        goto out;