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[PATCH 8/8] xfs: Introduce XFS_IOC_ZERO_RANGE

To: xfs@xxxxxxxxxxx
Subject: [PATCH 8/8] xfs: Introduce XFS_IOC_ZERO_RANGE
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Wed, 18 Aug 2010 21:36:19 +1000
In-reply-to: <1282131379-29932-1-git-send-email-david@xxxxxxxxxxxxx>
References: <1282131379-29932-1-git-send-email-david@xxxxxxxxxxxxx>
From: Dave Chinner <dchinner@xxxxxxxxxx>

XFS_IOC_ZERO_RANGE is the equivalent of an atomic XFS_IOC_UNRESVSP/
XFS_IOC_RESVSP call pair. It enabled ranges of written data to be
turned into zeroes without requiring IO or having to free and
reallocate the extents in the range given as would occur if we had
to punch and then preallocate them separately.  This enables
applications to zero parts of files very quickly without changing
the layout of the files in any way.

Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
---
 fs/xfs/linux-2.6/xfs_ioctl.c   |    3 ++-
 fs/xfs/linux-2.6/xfs_ioctl32.c |    1 +
 fs/xfs/xfs_bmap.c              |   12 +++++++++---
 fs/xfs/xfs_bmap.h              |    9 ++++++---
 fs/xfs/xfs_fs.h                |    1 +
 fs/xfs/xfs_vnodeops.c          |   10 ++++++++--
 6 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/fs/xfs/linux-2.6/xfs_ioctl.c b/fs/xfs/linux-2.6/xfs_ioctl.c
index 237f5ff..a9c4810 100644
--- a/fs/xfs/linux-2.6/xfs_ioctl.c
+++ b/fs/xfs/linux-2.6/xfs_ioctl.c
@@ -1292,7 +1292,8 @@ xfs_file_ioctl(
        case XFS_IOC_ALLOCSP64:
        case XFS_IOC_FREESP64:
        case XFS_IOC_RESVSP64:
-       case XFS_IOC_UNRESVSP64: {
+       case XFS_IOC_UNRESVSP64:
+       case XFS_IOC_ZERO_RANGE: {
                xfs_flock64_t           bf;
 
                if (copy_from_user(&bf, arg, sizeof(bf)))
diff --git a/fs/xfs/linux-2.6/xfs_ioctl32.c b/fs/xfs/linux-2.6/xfs_ioctl32.c
index 6c83f7f..464bcc7 100644
--- a/fs/xfs/linux-2.6/xfs_ioctl32.c
+++ b/fs/xfs/linux-2.6/xfs_ioctl32.c
@@ -574,6 +574,7 @@ xfs_file_compat_ioctl(
        case XFS_IOC_FSGEOMETRY_V1:
        case XFS_IOC_FSGROWFSDATA:
        case XFS_IOC_FSGROWFSRT:
+       case XFS_IOC_ZERO_RANGE:
                return xfs_file_ioctl(filp, cmd, p);
 #else
        case XFS_IOC_ALLOCSP_32:
diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c
index 23f14e5..d36770f 100644
--- a/fs/xfs/xfs_bmap.c
+++ b/fs/xfs/xfs_bmap.c
@@ -4744,8 +4744,12 @@ xfs_bmapi(
                 * Check if writing previously allocated but
                 * unwritten extents.
                 */
-               if (wr && mval->br_state == XFS_EXT_UNWRITTEN &&
-                   ((flags & (XFS_BMAPI_PREALLOC|XFS_BMAPI_DELAY)) == 0)) {
+               if (wr &&
+                   ((mval->br_state == XFS_EXT_UNWRITTEN &&
+                     ((flags & (XFS_BMAPI_PREALLOC|XFS_BMAPI_DELAY)) == 0)) ||
+                    (mval->br_state == XFS_EXT_NORM &&
+                     ((flags & (XFS_BMAPI_PREALLOC|XFS_BMAPI_CONVERT)) ==
+                               (XFS_BMAPI_PREALLOC|XFS_BMAPI_CONVERT))))) {
                        /*
                         * Modify (by adding) the state flag, if writing.
                         */
@@ -4757,7 +4761,9 @@ xfs_bmapi(
                                        *firstblock;
                                cur->bc_private.b.flist = flist;
                        }
-                       mval->br_state = XFS_EXT_NORM;
+                       mval->br_state = (mval->br_state == XFS_EXT_UNWRITTEN)
+                                               ? XFS_EXT_NORM
+                                               : XFS_EXT_UNWRITTEN;
                        error = xfs_bmap_add_extent(ip, lastx, &cur, mval,
                                firstblock, flist, &tmp_logflags,
                                whichfork, (flags & XFS_BMAPI_RSVBLOCKS));
diff --git a/fs/xfs/xfs_bmap.h b/fs/xfs/xfs_bmap.h
index b13569a..71ec9b6 100644
--- a/fs/xfs/xfs_bmap.h
+++ b/fs/xfs/xfs_bmap.h
@@ -74,9 +74,12 @@ typedef      struct xfs_bmap_free
 #define        XFS_BMAPI_IGSTATE       0x080   /* Ignore state - */
                                        /* combine contig. space */
 #define        XFS_BMAPI_CONTIG        0x100   /* must allocate only one 
extent */
-#define XFS_BMAPI_CONVERT      0x200   /* unwritten extent conversion - */
-                                       /* need write cache flushing and no */
-                                       /* additional allocation alignments */
+/*
+ * unwritten extent conversion - this needs write cache flushing and no 
additional
+ * allocation alignments. When specified with XFS_BMAPI_PREALLOC it converts
+ * from written to unwritten, otherwise convert from unwritten to written.
+ */
+#define XFS_BMAPI_CONVERT      0x200
 
 #define XFS_BMAPI_FLAGS \
        { XFS_BMAPI_WRITE,      "WRITE" }, \
diff --git a/fs/xfs/xfs_fs.h b/fs/xfs/xfs_fs.h
index 7cf7220..6af6518 100644
--- a/fs/xfs/xfs_fs.h
+++ b/fs/xfs/xfs_fs.h
@@ -446,6 +446,7 @@ typedef struct xfs_handle {
 /*     XFS_IOC_SETBIOSIZE ---- deprecated 46      */
 /*     XFS_IOC_GETBIOSIZE ---- deprecated 47      */
 #define XFS_IOC_GETBMAPX       _IOWR('X', 56, struct getbmap)
+#define XFS_IOC_ZERO_RANGE     _IOW ('X', 57, struct xfs_flock64)
 
 /*
  * ioctl commands that replace IRIX syssgi()'s
diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
index 66d585c..3cacf59 100644
--- a/fs/xfs/xfs_vnodeops.c
+++ b/fs/xfs/xfs_vnodeops.c
@@ -2272,7 +2272,7 @@ xfs_alloc_file_space(
        count = len;
        imapp = &imaps[0];
        nimaps = 1;
-       bmapi_flag = XFS_BMAPI_WRITE | (alloc_type ? XFS_BMAPI_PREALLOC : 0);
+       bmapi_flag = XFS_BMAPI_WRITE | alloc_type;
        startoffset_fsb = XFS_B_TO_FSBT(mp, offset);
        allocatesize_fsb = XFS_B_TO_FSB(mp, count);
 
@@ -2704,6 +2704,7 @@ xfs_change_file_space(
        xfs_off_t       llen;
        xfs_trans_t     *tp;
        struct iattr    iattr;
+       int             prealloc_type;
 
        if (!S_ISREG(ip->i_d.di_mode))
                return XFS_ERROR(EINVAL);
@@ -2746,12 +2747,17 @@ xfs_change_file_space(
         * size to be changed.
         */
        setprealloc = clrprealloc = 0;
+       prealloc_type = XFS_BMAPI_PREALLOC;
 
        switch (cmd) {
+       case XFS_IOC_ZERO_RANGE:
+               prealloc_type |= XFS_BMAPI_CONVERT;
+               xfs_tosspages(ip, startoffset, startoffset + bf->l_len, 0);
+               /* FALLTHRU */
        case XFS_IOC_RESVSP:
        case XFS_IOC_RESVSP64:
                error = xfs_alloc_file_space(ip, startoffset, bf->l_len,
-                                                               1, attr_flags);
+                                               prealloc_type, attr_flags);
                if (error)
                        return error;
                setprealloc = 1;
-- 
1.7.1

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