Commit 6881a229 authored by Alex Elder's avatar Alex Elder
Browse files

xfs: fix min bufsize bugs in two places 



This fixes a bug in two places that I found by inspection.  In
xlog_find_verify_cycle() and xlog_write_log_records(), the code
attempts to allocate a buffer to hold as many blocks as possible.
It gives up if the number of blocks to be allocated gets too small.
Right now it uses log->l_sectbb_log as that lower bound, but I'm
sure it's supposed to be the actual log sector size instead.  That
is, the lower bound should be (1 << log->l_sectbb_log).

Also define a simple macro xlog_sectbb(log) to represent the number
of basic blocks in a sector for the given log.

(No change from original submission; I have implemented Christoph's
suggestion about storing l_sectsize rather than l_sectbb_log in
a new, separate patch in this series.)

Signed-off-by: default avatarAlex Elder <aelder@sgi.com>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
parent a0e856b0

fs/xfs/xfs_log_recover.c

+17 −4
Original line number Diff line number Diff line
@@ -66,6 +66,9 @@ STATIC void xlog_recover_check_summary(xlog_t *); 
	((bbs + (log)->l_sectbb_mask + 1) & ~(log)->l_sectbb_mask) : (bbs) )

#define XLOG_SECTOR_ROUNDDOWN_BLKNO(log, bno)	((bno) & ~(log)->l_sectbb_mask)



/* Number of basic blocks in a log sector */

#define xlog_sectbb(log) (1 << (log)->l_sectbb_log)



STATIC xfs_buf_t *

xlog_get_bp(

	xlog_t		*log,
@@ -376,12 +379,16 @@ xlog_find_verify_cycle( 
	xfs_caddr_t	buf = NULL;

	int		error = 0;



	/*

	 * Greedily allocate a buffer big enough to handle the full

	 * range of basic blocks we'll be examining.  If that fails,

	 * try a smaller size.  We need to be able to read at least

	 * a log sector, or we're out of luck.

	 */

	bufblks = 1 << ffs(nbblks);



	while (!(bp = xlog_get_bp(log, bufblks))) {

		/* can't get enough memory to do everything in one big buffer */

		bufblks >>= 1;

		if (bufblks <= log->l_sectbb_log)

		if (bufblks < xlog_sectbb(log))

			return ENOMEM;

	}
@@ -1158,10 +1165,16 @@ xlog_write_log_records( 
	int		error = 0;

	int		i, j = 0;



	/*

	 * Greedily allocate a buffer big enough to handle the full

	 * range of basic blocks to be written.  If that fails, try

	 * a smaller size.  We need to be able to write at least a

	 * log sector, or we're out of luck.

	 */

	bufblks = 1 << ffs(blocks);

	while (!(bp = xlog_get_bp(log, bufblks))) {

		bufblks >>= 1;

		if (bufblks <= log->l_sectbb_log)

		if (bufblks < xlog_sectbb(log))

			return ENOMEM;

	}

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