JBD2__JOURNAL_START(9)              The Linux Journalling API              JBD2__JOURNAL_START(9)



NAME
       jbd2__journal_start - Obtain a new handle.

SYNOPSIS
       handle_t * jbd2__journal_start(journal_t * journal, int nblocks, int rsv_blocks,
                                      gfp_t gfp_mask, unsigned int type, unsigned int line_no);

ARGUMENTS
       journal
           Journal to start transaction on.

       nblocks
           number of block buffer we might modify

       rsv_blocks
           -- undescribed --

       gfp_mask
           -- undescribed --

       type
           -- undescribed --

       line_no
           -- undescribed --

DESCRIPTION
       We make sure that the transaction can guarantee at least nblocks of modified buffers in
       the log. We block until the log can guarantee that much space. Additionally, if rsv_blocks
       > 0, we also create another handle with rsv_blocks reserved blocks in the journal. This
       handle is is stored in h_rsv_handle. It is not attached to any particular transaction and
       thus doesn't block transaction commit. If the caller uses this reserved handle, it has to
       set h_rsv_handle to NULL as otherwise jbd2_journal_stop on the parent handle will dispose
       the reserved one. Reserved handle has to be converted to a normal handle using
       jbd2_journal_start_reserved before it can be used.

       Return a pointer to a newly allocated handle, or an ERR_PTR value on failure.

AUTHORS
       Roger Gammans <rgammans AT computer-surgery.uk>
           Author.

       Stephen Tweedie <sct AT redhat.com>
           Author.

COPYRIGHT
Kernel Hackers Manual 4.8.                 January 2017                    JBD2__JOURNAL_START(9)