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| author | Ross Zwisler <ross.zwisler@linux.intel.com> | 2015-10-13 16:25:37 -0600 |
|---|---|---|
| committer | Jan Kara <jack@suse.com> | 2015-10-19 14:40:54 +0200 |
| commit | 5726b27b09cc92452b543764899a07e7c8037edd (patch) | |
| tree | a24cd32cee813259c61e6fb07ce4ba7d93a254f8 /fs/ext2/inode.c | |
| parent | d4eb6dee471250661a5183a7336b18c85990e26d (diff) | |
| download | linux-5726b27b09cc92452b543764899a07e7c8037edd.tar.bz2 | |
ext2: Add locking for DAX faults
Add locking to ensure that DAX faults are isolated from ext2 operations
that modify the data blocks allocation for an inode. This is intended to
be analogous to the work being done in XFS by Dave Chinner:
http://www.spinics.net/lists/linux-fsdevel/msg90260.html
Compared with XFS the ext2 case is greatly simplified by the fact that ext2
already allocates and zeros new blocks before they are returned as part of
ext2_get_block(), so DAX doesn't need to worry about getting unmapped or
unwritten buffer heads.
This means that the only work we need to do in ext2 is to isolate the DAX
faults from inode block allocation changes. I believe this just means that
we need to isolate the DAX faults from truncate operations.
The newly introduced dax_sem is intended to replicate the protection
offered by i_mmaplock in XFS. In addition to truncate the i_mmaplock also
protects XFS operations like hole punching, fallocate down, extent
manipulation IOCTLS like xfs_ioc_space() and extent swapping. Truncate is
the only one of these operations supported by ext2.
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.com>
Diffstat (limited to 'fs/ext2/inode.c')
| -rw-r--r-- | fs/ext2/inode.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c index c60a248c640c..0aa9bf6e6e53 100644 --- a/fs/ext2/inode.c +++ b/fs/ext2/inode.c @@ -1085,6 +1085,7 @@ static void ext2_free_branches(struct inode *inode, __le32 *p, __le32 *q, int de ext2_free_data(inode, p, q); } +/* dax_sem must be held when calling this function */ static void __ext2_truncate_blocks(struct inode *inode, loff_t offset) { __le32 *i_data = EXT2_I(inode)->i_data; @@ -1100,6 +1101,10 @@ static void __ext2_truncate_blocks(struct inode *inode, loff_t offset) blocksize = inode->i_sb->s_blocksize; iblock = (offset + blocksize-1) >> EXT2_BLOCK_SIZE_BITS(inode->i_sb); +#ifdef CONFIG_FS_DAX + WARN_ON(!rwsem_is_locked(&ei->dax_sem)); +#endif + n = ext2_block_to_path(inode, iblock, offsets, NULL); if (n == 0) return; @@ -1185,7 +1190,10 @@ static void ext2_truncate_blocks(struct inode *inode, loff_t offset) return; if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) return; + + dax_sem_down_write(EXT2_I(inode)); __ext2_truncate_blocks(inode, offset); + dax_sem_up_write(EXT2_I(inode)); } static int ext2_setsize(struct inode *inode, loff_t newsize) @@ -1213,8 +1221,10 @@ static int ext2_setsize(struct inode *inode, loff_t newsize) if (error) return error; + dax_sem_down_write(EXT2_I(inode)); truncate_setsize(inode, newsize); __ext2_truncate_blocks(inode, newsize); + dax_sem_up_write(EXT2_I(inode)); inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC; if (inode_needs_sync(inode)) { |