From: Josef Bacik Date: Wed, 10 Feb 2021 22:14:33 +0000 (-0500) Subject: btrfs: add a i_mmap_lock to our inode X-Git-Tag: v5.15~953^2~124 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=8318ba79eeeb1ab69bea1cc4386d5a185abc0cb8;p=platform%2Fkernel%2Flinux-starfive.git btrfs: add a i_mmap_lock to our inode We need to be able to exclude page_mkwrite from happening concurrently with certain operations. To facilitate this, add a i_mmap_lock to our inode, down_read() it in our mkwrite, and add a new ILOCK flag to indicate that we want to take the i_mmap_lock as well. I used pahole to check the size of the btrfs_inode, the sizes are as follows no lockdep: before: 1120 (3 per 4k page) after: 1160 (3 per 4k page) lockdep: before: 2072 (1 per 4k page) after: 2224 (1 per 4k page) We're slightly larger but it doesn't change how many objects we can fit per page. Reviewed-by: Filipe Manana Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba --- diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h index 28e202e..26837c3 100644 --- a/fs/btrfs/btrfs_inode.h +++ b/fs/btrfs/btrfs_inode.h @@ -220,6 +220,7 @@ struct btrfs_inode { /* Hook into fs_info->delayed_iputs */ struct list_head delayed_iput; + struct rw_semaphore i_mmap_lock; struct inode vfs_inode; }; diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 5776026..751ab9f 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -3178,6 +3178,7 @@ extern const struct iomap_dio_ops btrfs_dio_ops; /* Inode locking type flags, by default the exclusive lock is taken */ #define BTRFS_ILOCK_SHARED (1U << 0) #define BTRFS_ILOCK_TRY (1U << 1) +#define BTRFS_ILOCK_MMAP (1U << 2) int btrfs_inode_lock(struct inode *inode, unsigned int ilock_flags); void btrfs_inode_unlock(struct inode *inode, unsigned int ilock_flags); diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index df38540..93f735c 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -102,6 +102,7 @@ static void __endio_write_update_ordered(struct btrfs_inode *inode, * BTRFS_ILOCK_SHARED - acquire a shared lock on the inode * BTRFS_ILOCK_TRY - try to acquire the lock, if fails on first attempt * return -EAGAIN + * BTRFS_ILOCK_MMAP - acquire a write lock on the i_mmap_lock */ int btrfs_inode_lock(struct inode *inode, unsigned int ilock_flags) { @@ -122,6 +123,8 @@ int btrfs_inode_lock(struct inode *inode, unsigned int ilock_flags) } inode_lock(inode); } + if (ilock_flags & BTRFS_ILOCK_MMAP) + down_write(&BTRFS_I(inode)->i_mmap_lock); return 0; } @@ -133,6 +136,8 @@ int btrfs_inode_lock(struct inode *inode, unsigned int ilock_flags) */ void btrfs_inode_unlock(struct inode *inode, unsigned int ilock_flags) { + if (ilock_flags & BTRFS_ILOCK_MMAP) + up_write(&BTRFS_I(inode)->i_mmap_lock); if (ilock_flags & BTRFS_ILOCK_SHARED) inode_unlock_shared(inode); else @@ -8540,6 +8545,7 @@ vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf) ret = VM_FAULT_NOPAGE; /* make the VM retry the fault */ again: + down_read(&BTRFS_I(inode)->i_mmap_lock); lock_page(page); size = i_size_read(inode); @@ -8568,6 +8574,7 @@ again: unlock_extent_cached(io_tree, page_start, page_end, &cached_state); unlock_page(page); + up_read(&BTRFS_I(inode)->i_mmap_lock); btrfs_start_ordered_extent(ordered, 1); btrfs_put_ordered_extent(ordered); goto again; @@ -8625,6 +8632,7 @@ again: BTRFS_I(inode)->last_log_commit = BTRFS_I(inode)->root->last_log_commit; unlock_extent_cached(io_tree, page_start, page_end, &cached_state); + up_read(&BTRFS_I(inode)->i_mmap_lock); btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE); sb_end_pagefault(inode->i_sb); @@ -8633,6 +8641,7 @@ again: out_unlock: unlock_page(page); + up_read(&BTRFS_I(inode)->i_mmap_lock); out: btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE); btrfs_delalloc_release_space(BTRFS_I(inode), data_reserved, page_start, @@ -8884,6 +8893,7 @@ struct inode *btrfs_alloc_inode(struct super_block *sb) INIT_LIST_HEAD(&ei->delalloc_inodes); INIT_LIST_HEAD(&ei->delayed_iput); RB_CLEAR_NODE(&ei->rb_node); + init_rwsem(&ei->i_mmap_lock); return inode; }