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| author | Jan Kara <jack@suse.com> | 2015-12-07 15:10:26 -0500 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2015-12-07 15:10:26 -0500 |
| commit | c86d8db33a922da808a5560aa15ed663a9569b37 (patch) | |
| tree | 64ee357906cb5d2a0408a9613532460e49b7b6c9 /fs/ext4/inode.c | |
| parent | 53085fac02d12fcd29a9cb074ec480ff0f77ae5c (diff) | |
| download | linux-stable-c86d8db33a922da808a5560aa15ed663a9569b37.tar.gz linux-stable-c86d8db33a922da808a5560aa15ed663a9569b37.tar.bz2 linux-stable-c86d8db33a922da808a5560aa15ed663a9569b37.zip | |
ext4: implement allocation of pre-zeroed blocks
DAX page fault path needs to get blocks that are pre-zeroed to avoid
races when two concurrent page faults happen in the same block of a
file. Implement support for this in ext4_map_blocks().
Signed-off-by: Jan Kara <jack@suse.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4/inode.c')
| -rw-r--r-- | fs/ext4/inode.c | 25 |
1 files changed, 22 insertions, 3 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 0c9a5ee3e106..4241d0cff062 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -637,13 +637,29 @@ found: } /* + * We have to zeroout blocks before inserting them into extent + * status tree. Otherwise someone could look them up there and + * use them before they are really zeroed. + */ + if (flags & EXT4_GET_BLOCKS_ZERO && + map->m_flags & EXT4_MAP_MAPPED && + map->m_flags & EXT4_MAP_NEW) { + ret = ext4_issue_zeroout(inode, map->m_lblk, + map->m_pblk, map->m_len); + if (ret) { + retval = ret; + goto out_sem; + } + } + + /* * If the extent has been zeroed out, we don't need to update * extent status tree. */ if ((flags & EXT4_GET_BLOCKS_PRE_IO) && ext4_es_lookup_extent(inode, map->m_lblk, &es)) { if (ext4_es_is_written(&es)) - goto has_zeroout; + goto out_sem; } status = map->m_flags & EXT4_MAP_UNWRITTEN ? EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN; @@ -654,11 +670,13 @@ found: status |= EXTENT_STATUS_DELAYED; ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len, map->m_pblk, status); - if (ret < 0) + if (ret < 0) { retval = ret; + goto out_sem; + } } -has_zeroout: +out_sem: up_write((&EXT4_I(inode)->i_data_sem)); if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) { ret = check_block_validity(inode, map); @@ -3083,6 +3101,7 @@ int ext4_get_block_dax(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create) { int flags = EXT4_GET_BLOCKS_PRE_IO | EXT4_GET_BLOCKS_UNWRIT_EXT; + if (create) flags |= EXT4_GET_BLOCKS_CREATE; ext4_debug("ext4_get_block_dax: inode %lu, create flag %d\n", |