btrfs: introduce btrfs_write_check()
btrfs_write_check() checks write parameters in one place before beginning a write. This does away with inode_unlock() after every check. In the later patches, it will help push inode_lock/unlock() in buffered and direct write functions respectively. generic_write_checks needs to be called before as it could truncate iov_iter and its return used as count. Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Goldwyn Rodrigues
David Sterba
Родитель
c86537a42f
Коммит
b8d8e1fd57
151
fs/btrfs/file.c
151
fs/btrfs/file.c
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@ -1564,6 +1564,79 @@ void btrfs_check_nocow_unlock(struct btrfs_inode *inode)
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btrfs_drew_write_unlock(&inode->root->snapshot_lock);
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}
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static void update_time_for_write(struct inode *inode)
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{
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struct timespec64 now;
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if (IS_NOCMTIME(inode))
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return;
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now = current_time(inode);
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if (!timespec64_equal(&inode->i_mtime, &now))
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inode->i_mtime = now;
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if (!timespec64_equal(&inode->i_ctime, &now))
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inode->i_ctime = now;
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if (IS_I_VERSION(inode))
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inode_inc_iversion(inode);
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}
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static int btrfs_write_check(struct kiocb *iocb, struct iov_iter *from,
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size_t count)
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{
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struct file *file = iocb->ki_filp;
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struct inode *inode = file_inode(file);
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struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
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loff_t pos = iocb->ki_pos;
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int ret;
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loff_t oldsize;
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loff_t start_pos;
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if (iocb->ki_flags & IOCB_NOWAIT) {
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size_t nocow_bytes = count;
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/* We will allocate space in case nodatacow is not set, so bail */
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if (check_nocow_nolock(BTRFS_I(inode), pos, &nocow_bytes) <= 0)
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return -EAGAIN;
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/*
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* There are holes in the range or parts of the range that must
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* be COWed (shared extents, RO block groups, etc), so just bail
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* out.
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*/
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if (nocow_bytes < count)
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return -EAGAIN;
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}
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current->backing_dev_info = inode_to_bdi(inode);
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ret = file_remove_privs(file);
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if (ret)
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return ret;
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/*
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* We reserve space for updating the inode when we reserve space for the
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* extent we are going to write, so we will enospc out there. We don't
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* need to start yet another transaction to update the inode as we will
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* update the inode when we finish writing whatever data we write.
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*/
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update_time_for_write(inode);
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start_pos = round_down(pos, fs_info->sectorsize);
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oldsize = i_size_read(inode);
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if (start_pos > oldsize) {
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/* Expand hole size to cover write data, preventing empty gap */
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loff_t end_pos = round_up(pos + count, fs_info->sectorsize);
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ret = btrfs_cont_expand(inode, oldsize, end_pos);
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if (ret) {
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current->backing_dev_info = NULL;
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return ret;
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}
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}
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return 0;
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}
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static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
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struct iov_iter *i)
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{
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@ -1873,24 +1946,6 @@ out:
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return written ? written : err;
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}
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static void update_time_for_write(struct inode *inode)
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{
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struct timespec64 now;
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if (IS_NOCMTIME(inode))
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return;
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now = current_time(inode);
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if (!timespec64_equal(&inode->i_mtime, &now))
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inode->i_mtime = now;
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if (!timespec64_equal(&inode->i_ctime, &now))
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inode->i_ctime = now;
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if (IS_I_VERSION(inode))
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inode_inc_iversion(inode);
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}
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static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
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struct iov_iter *from)
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{
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@ -1898,14 +1953,9 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
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struct inode *inode = file_inode(file);
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struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
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struct btrfs_root *root = BTRFS_I(inode)->root;
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u64 start_pos;
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u64 end_pos;
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ssize_t num_written = 0;
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const bool sync = iocb->ki_flags & IOCB_DSYNC;
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ssize_t err;
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loff_t pos;
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size_t count;
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loff_t oldsize;
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/*
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* If the fs flips readonly due to some impossible error, although we
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@ -1932,57 +1982,10 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
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return err;
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}
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pos = iocb->ki_pos;
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count = iov_iter_count(from);
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if (iocb->ki_flags & IOCB_NOWAIT) {
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size_t nocow_bytes = count;
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/*
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* We will allocate space in case nodatacow is not set,
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* so bail
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*/
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if (check_nocow_nolock(BTRFS_I(inode), pos, &nocow_bytes)
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<= 0) {
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inode_unlock(inode);
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return -EAGAIN;
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}
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/*
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* There are holes in the range or parts of the range that must
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* be COWed (shared extents, RO block groups, etc), so just bail
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* out.
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*/
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if (nocow_bytes < count) {
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inode_unlock(inode);
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return -EAGAIN;
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}
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}
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current->backing_dev_info = inode_to_bdi(inode);
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err = file_remove_privs(file);
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if (err) {
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err = btrfs_write_check(iocb, from, err);
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if (err < 0) {
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inode_unlock(inode);
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goto out;
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}
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/*
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* We reserve space for updating the inode when we reserve space for the
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* extent we are going to write, so we will enospc out there. We don't
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* need to start yet another transaction to update the inode as we will
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* update the inode when we finish writing whatever data we write.
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*/
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update_time_for_write(inode);
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start_pos = round_down(pos, fs_info->sectorsize);
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oldsize = i_size_read(inode);
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if (start_pos > oldsize) {
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/* Expand hole size to cover write data, preventing empty gap */
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end_pos = round_up(pos + count,
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fs_info->sectorsize);
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err = btrfs_cont_expand(inode, oldsize, end_pos);
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if (err) {
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inode_unlock(inode);
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goto out;
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}
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return err;
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}
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if (sync)
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@ -2042,7 +2045,7 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
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if (sync)
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atomic_dec(&BTRFS_I(inode)->sync_writers);
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out:
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current->backing_dev_info = NULL;
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return num_written ? num_written : err;
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}
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