diff options
| author | Jan Kara <jack@suse.cz> | 2021-01-28 19:19:45 +0100 |
|---|---|---|
| committer | Jan Kara <jack@suse.cz> | 2021-07-13 13:14:27 +0200 |
| commit | 730633f0b7f951726e87f912a6323641f674ae34 (patch) | |
| tree | 1c4a6eb5ddbc0c28e6d37a1418ec259cb6daef27 /fs/inode.c | |
| parent | documentation: Sync file_operations members with reality (diff) | |
| download | linux-730633f0b7f951726e87f912a6323641f674ae34.tar.xz linux-730633f0b7f951726e87f912a6323641f674ae34.zip | |
mm: Protect operations adding pages to page cache with invalidate_lock
Currently, serializing operations such as page fault, read, or readahead
against hole punching is rather difficult. The basic race scheme is
like:
fallocate(FALLOC_FL_PUNCH_HOLE) read / fault / ..
truncate_inode_pages_range()
<create pages in page
cache here>
<update fs block mapping and free blocks>
Now the problem is in this way read / page fault / readahead can
instantiate pages in page cache with potentially stale data (if blocks
get quickly reused). Avoiding this race is not simple - page locks do
not work because we want to make sure there are *no* pages in given
range. inode->i_rwsem does not work because page fault happens under
mmap_sem which ranks below inode->i_rwsem. Also using it for reads makes
the performance for mixed read-write workloads suffer.
So create a new rw_semaphore in the address_space - invalidate_lock -
that protects adding of pages to page cache for page faults / reads /
readahead.
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'fs/inode.c')
| -rw-r--r-- | fs/inode.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/fs/inode.c b/fs/inode.c index c93500d84264..84c528cd1955 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -190,6 +190,8 @@ int inode_init_always(struct super_block *sb, struct inode *inode) mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE); mapping->private_data = NULL; mapping->writeback_index = 0; + __init_rwsem(&mapping->invalidate_lock, "mapping.invalidate_lock", + &sb->s_type->invalidate_lock_key); inode->i_private = NULL; inode->i_mapping = mapping; INIT_HLIST_HEAD(&inode->i_dentry); /* buggered by rcu freeing */ |