ext4: get rid of EXT4_GET_BLOCKS_NO_LOCK flag
When dioread_nolock mode is enabled, we grab i_data_sem in ext4_ext_direct_IO() and therefore we need to instruct _ext4_get_block() not to grab i_data_sem again using EXT4_GET_BLOCKS_NO_LOCK. However holding i_data_sem over overwrite direct IO isn't needed these days. We have exclusion against truncate / hole punching because we increase i_dio_count under i_mutex in ext4_ext_direct_IO() so once ext4_file_write_iter() verifies blocks are allocated & written, they are guaranteed to stay so during the whole direct IO even after we drop i_mutex. So we can just remove this locking abuse and the no longer necessary EXT4_GET_BLOCKS_NO_LOCK flag. Signed-off-by: Jan Kara <jack@suse.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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@ -555,10 +555,8 @@ enum {
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#define EXT4_GET_BLOCKS_NO_NORMALIZE 0x0040
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/* Request will not result in inode size update (user for fallocate) */
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#define EXT4_GET_BLOCKS_KEEP_SIZE 0x0080
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/* Do not take i_data_sem locking in ext4_map_blocks */
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#define EXT4_GET_BLOCKS_NO_LOCK 0x0100
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/* Convert written extents to unwritten */
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#define EXT4_GET_BLOCKS_CONVERT_UNWRITTEN 0x0200
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#define EXT4_GET_BLOCKS_CONVERT_UNWRITTEN 0x0100
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/*
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* The bit position of these flags must not overlap with any of the
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@ -403,8 +403,7 @@ static void ext4_map_blocks_es_recheck(handle_t *handle,
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* out taking i_data_sem. So at the time the unwritten extent
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* could be converted.
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*/
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if (!(flags & EXT4_GET_BLOCKS_NO_LOCK))
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down_read(&EXT4_I(inode)->i_data_sem);
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down_read(&EXT4_I(inode)->i_data_sem);
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if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
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retval = ext4_ext_map_blocks(handle, inode, map, flags &
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EXT4_GET_BLOCKS_KEEP_SIZE);
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@ -412,8 +411,7 @@ static void ext4_map_blocks_es_recheck(handle_t *handle,
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retval = ext4_ind_map_blocks(handle, inode, map, flags &
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EXT4_GET_BLOCKS_KEEP_SIZE);
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}
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if (!(flags & EXT4_GET_BLOCKS_NO_LOCK))
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up_read((&EXT4_I(inode)->i_data_sem));
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up_read((&EXT4_I(inode)->i_data_sem));
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/*
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* We don't check m_len because extent will be collpased in status
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@ -509,8 +507,7 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
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* Try to see if we can get the block without requesting a new
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* file system block.
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*/
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if (!(flags & EXT4_GET_BLOCKS_NO_LOCK))
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down_read(&EXT4_I(inode)->i_data_sem);
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down_read(&EXT4_I(inode)->i_data_sem);
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if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
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retval = ext4_ext_map_blocks(handle, inode, map, flags &
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EXT4_GET_BLOCKS_KEEP_SIZE);
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@ -541,8 +538,7 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
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if (ret < 0)
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retval = ret;
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}
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if (!(flags & EXT4_GET_BLOCKS_NO_LOCK))
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up_read((&EXT4_I(inode)->i_data_sem));
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up_read((&EXT4_I(inode)->i_data_sem));
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found:
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if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
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@ -674,7 +670,7 @@ static int _ext4_get_block(struct inode *inode, sector_t iblock,
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map.m_lblk = iblock;
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map.m_len = bh->b_size >> inode->i_blkbits;
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if (flags && !(flags & EXT4_GET_BLOCKS_NO_LOCK) && !handle) {
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if (flags && !handle) {
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/* Direct IO write... */
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if (map.m_len > DIO_MAX_BLOCKS)
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map.m_len = DIO_MAX_BLOCKS;
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@ -879,9 +875,6 @@ int do_journal_get_write_access(handle_t *handle,
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return ret;
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}
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static int ext4_get_block_write_nolock(struct inode *inode, sector_t iblock,
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struct buffer_head *bh_result, int create);
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#ifdef CONFIG_EXT4_FS_ENCRYPTION
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static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
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get_block_t *get_block)
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@ -3054,13 +3047,21 @@ int ext4_get_block_write(struct inode *inode, sector_t iblock,
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EXT4_GET_BLOCKS_IO_CREATE_EXT);
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}
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static int ext4_get_block_write_nolock(struct inode *inode, sector_t iblock,
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static int ext4_get_block_overwrite(struct inode *inode, sector_t iblock,
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struct buffer_head *bh_result, int create)
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{
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ext4_debug("ext4_get_block_write_nolock: inode %lu, create flag %d\n",
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int ret;
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ext4_debug("ext4_get_block_overwrite: inode %lu, create flag %d\n",
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inode->i_ino, create);
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return _ext4_get_block(inode, iblock, bh_result,
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EXT4_GET_BLOCKS_NO_LOCK);
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ret = _ext4_get_block(inode, iblock, bh_result, 0);
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/*
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* Blocks should have been preallocated! ext4_file_write_iter() checks
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* that.
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*/
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WARN_ON_ONCE(!buffer_mapped(bh_result));
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return ret;
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}
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int ext4_get_block_dax(struct inode *inode, sector_t iblock,
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@ -3143,10 +3144,8 @@ static ssize_t ext4_ext_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
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/* If we do a overwrite dio, i_mutex locking can be released */
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overwrite = *((int *)iocb->private);
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if (overwrite) {
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down_read(&EXT4_I(inode)->i_data_sem);
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if (overwrite)
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mutex_unlock(&inode->i_mutex);
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}
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/*
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* We could direct write to holes and fallocate.
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@ -3189,7 +3188,7 @@ static ssize_t ext4_ext_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
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}
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if (overwrite) {
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get_block_func = ext4_get_block_write_nolock;
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get_block_func = ext4_get_block_overwrite;
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} else {
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get_block_func = ext4_get_block_write;
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dio_flags = DIO_LOCKING;
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@ -3245,10 +3244,8 @@ retake_lock:
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if (iov_iter_rw(iter) == WRITE)
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inode_dio_end(inode);
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/* take i_mutex locking again if we do a ovewrite dio */
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if (overwrite) {
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up_read(&EXT4_I(inode)->i_data_sem);
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if (overwrite)
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mutex_lock(&inode->i_mutex);
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}
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return ret;
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}
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@ -42,8 +42,7 @@ struct extent_status;
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{ EXT4_GET_BLOCKS_CONVERT, "CONVERT" }, \
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{ EXT4_GET_BLOCKS_METADATA_NOFAIL, "METADATA_NOFAIL" }, \
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{ EXT4_GET_BLOCKS_NO_NORMALIZE, "NO_NORMALIZE" }, \
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{ EXT4_GET_BLOCKS_KEEP_SIZE, "KEEP_SIZE" }, \
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{ EXT4_GET_BLOCKS_NO_LOCK, "NO_LOCK" })
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{ EXT4_GET_BLOCKS_KEEP_SIZE, "KEEP_SIZE" })
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#define show_mflags(flags) __print_flags(flags, "", \
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{ EXT4_MAP_NEW, "N" }, \
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