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[XFS] Introduce two new mount options (nolargeio/largeio) to allow

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filesystems to expose the filesystem stripe width in stat(2) rather than
the page cache size. This allows applications requiring high bandwidth to
easily determine the optimum I/O size for the underlying filesystem. The
default is to report the page cache size (i.e. "nolargeio").

SGI-PV: 942818
SGI-Modid: xfs-linux:xfs-kern:23830a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>
This commit is contained in:
David Chinner
2005-11-02 10:33:05 +11:00
committed by Nathan Scott
parent ee34807a65
commit e8c8b3a79d
6 changed files with 43 additions and 35 deletions
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27
fs/xfs/xfs_mount.h
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@@ -421,6 +421,9 @@ typedef struct xfs_mount {
* allocation */
#define XFS_MOUNT_IHASHSIZE 0x00100000 /* inode hash table size */
#define XFS_MOUNT_DIRSYNC 0x00200000 /* synchronous directory ops */
#define XFS_MOUNT_COMPAT_IOSIZE 0x00400000 /* don't report large preferred
* I/O size in stat() */
/*
* Default minimum read and write sizes.
@@ -442,6 +445,30 @@ typedef struct xfs_mount {
#define XFS_WSYNC_READIO_LOG 15 /* 32K */
#define XFS_WSYNC_WRITEIO_LOG 14 /* 16K */
/*
* Allow large block sizes to be reported to userspace programs if the
* "largeio" mount option is used.
*
* If compatibility mode is specified, simply return the basic unit of caching
* so that we don't get inefficient read/modify/write I/O from user apps.
* Otherwise....
*
* If the underlying volume is a stripe, then return the stripe width in bytes
* as the recommended I/O size. It is not a stripe and we've set a default
* buffered I/O size, return that, otherwise return the compat default.
*/
static inline unsigned long
xfs_preferred_iosize(xfs_mount_t *mp)
{
if (mp->m_flags & XFS_MOUNT_COMPAT_IOSIZE)
return PAGE_CACHE_SIZE;
return (mp->m_swidth ?
(mp->m_swidth << mp->m_sb.sb_blocklog) :
((mp->m_flags & XFS_MOUNT_DFLT_IOSIZE) ?
(1 << (int)MAX(mp->m_readio_log, mp->m_writeio_log)) :
PAGE_CACHE_SIZE));
}
#define XFS_MAXIOFFSET(mp) ((mp)->m_maxioffset)
#define XFS_FORCED_SHUTDOWN(mp) ((mp)->m_flags & XFS_MOUNT_FS_SHUTDOWN)