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libminixfs: do not flush blocks that are in use

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This removes an implicit requirement for the way the libminixfs API is
to be used, namely that a block is to be marked as dirty only once its
contents have been fully updated, within a single get_block/put_block
window.  The requirement may not be appropriate for all file systems.

Change-Id: I6a129d51b1a5e9aec1572039dc7c1c82dd795db5
This commit is contained in:
David van Moolenbroek 2015-03-29 12:30:45 +00:00
parent cb9453ca63
commit b8f6d4a649
1 changed files with 8 additions and 4 deletions
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12
minix/lib/libminixfs/cache.c
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@ -732,7 +732,7 @@ void lmfs_flushdev(dev_t dev)
/* Flush all dirty blocks for one device. */ /* Flush all dirty blocks for one device. */
register struct buf *bp; register struct buf *bp;
static struct buf **dirty; /* static so it isn't on stack */ static struct buf **dirty;
static unsigned int dirtylistsize = 0; static unsigned int dirtylistsize = 0;
int ndirty; int ndirty;
@ -747,9 +747,13 @@ void lmfs_flushdev(dev_t dev)
} }
for (bp = &buf[0], ndirty = 0; bp < &buf[nr_bufs]; bp++) { for (bp = &buf[0], ndirty = 0; bp < &buf[nr_bufs]; bp++) {
if (!lmfs_isclean(bp) && bp->lmfs_dev == dev) { /* Do not flush dirty blocks that are in use (lmfs_count>0): the file
dirty[ndirty++] = bp; * system may mark the block as dirty before changing its contents, in
} * which case the new contents could end up being lost.
*/
if (!lmfs_isclean(bp) && bp->lmfs_dev == dev && bp->lmfs_count == 0) {
dirty[ndirty++] = bp;
}
} }
lmfs_rw_scattered(dev, dirty, ndirty, WRITING); lmfs_rw_scattered(dev, dirty, ndirty, WRITING);