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[PATCH 1/2] xfs: a couple getbmap cleanups

To: xfs@xxxxxxxxxxx
Subject: [PATCH 1/2] xfs: a couple getbmap cleanups
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Tue, 24 Feb 2009 08:38:58 -0500
User-agent: Mutt/1.5.18 (2008-05-17)
 - reshuffle various conditionals for data vs attr fork to make the code
   more readable
 - do fine-grainded goto-based error handling
 - exit early from conditionals instead of keeping a long else branch
   around
 - allow kmem_alloc to fail

Signed-off-by: Christoph Hellwig <hch@xxxxxx>

Index: xfs/fs/xfs/xfs_bmap.c
===================================================================
--- xfs.orig/fs/xfs/xfs_bmap.c  2009-02-23 18:08:35.352924726 +0100
+++ xfs/fs/xfs/xfs_bmap.c       2009-02-23 18:23:49.527051836 +0100
@@ -5857,7 +5857,7 @@ xfs_getbmap(
        void                    *arg)           /* formatter arg */
 {
        __int64_t               bmvend;         /* last block requested */
-       int                     error;          /* return value */
+       int                     error = 0;      /* return value */
        __int64_t               fixlen;         /* length for -1 case */
        int                     i;              /* extent number */
        int                     lock;           /* lock state */
@@ -5876,30 +5876,8 @@ xfs_getbmap(
 
        mp = ip->i_mount;
        iflags = bmv->bmv_iflags;
-
        whichfork = iflags & BMV_IF_ATTRFORK ? XFS_ATTR_FORK : XFS_DATA_FORK;
 
-       /*      If the BMV_IF_NO_DMAPI_READ interface bit specified, do not
-        *      generate a DMAPI read event.  Otherwise, if the DM_EVENT_READ
-        *      bit is set for the file, generate a read event in order
-        *      that the DMAPI application may do its thing before we return
-        *      the extents.  Usually this means restoring user file data to
-        *      regions of the file that look like holes.
-        *
-        *      The "old behavior" (from XFS_IOC_GETBMAP) is to not specify
-        *      BMV_IF_NO_DMAPI_READ so that read events are generated.
-        *      If this were not true, callers of ioctl( XFS_IOC_GETBMAP )
-        *      could misinterpret holes in a DMAPI file as true holes,
-        *      when in fact they may represent offline user data.
-        */
-       if ((iflags & BMV_IF_NO_DMAPI_READ) == 0 &&
-           DM_EVENT_ENABLED(ip, DM_EVENT_READ) &&
-           whichfork == XFS_DATA_FORK) {
-               error = XFS_SEND_DATA(mp, DM_EVENT_READ, ip, 0, 0, 0, NULL);
-               if (error)
-                       return XFS_ERROR(error);
-       }
-
        if (whichfork == XFS_ATTR_FORK) {
                if (XFS_IFORK_Q(ip)) {
                        if (ip->i_d.di_aformat != XFS_DINODE_FMT_EXTENTS &&
@@ -5913,11 +5891,37 @@ xfs_getbmap(
                                         ip->i_mount);
                        return XFS_ERROR(EFSCORRUPTED);
                }
-       } else if (ip->i_d.di_format != XFS_DINODE_FMT_EXTENTS &&
-                  ip->i_d.di_format != XFS_DINODE_FMT_BTREE &&
-                  ip->i_d.di_format != XFS_DINODE_FMT_LOCAL)
-               return XFS_ERROR(EINVAL);
-       if (whichfork == XFS_DATA_FORK) {
+
+               prealloced = 0;
+               fixlen = 1LL << 32;
+       } else {
+               /*
+                * If the BMV_IF_NO_DMAPI_READ interface bit specified, do
+                * not generate a DMAPI read event.  Otherwise, if the
+                * DM_EVENT_READ bit is set for the file, generate a read
+                * event in order that the DMAPI application may do its thing
+                * before we return the extents.  Usually this means restoring
+                * user file data to regions of the file that look like holes.
+                *
+                * The "old behavior" (from XFS_IOC_GETBMAP) is to not specify
+                * BMV_IF_NO_DMAPI_READ so that read events are generated.
+                * If this were not true, callers of ioctl(XFS_IOC_GETBMAP)
+                * could misinterpret holes in a DMAPI file as true holes,
+                * when in fact they may represent offline user data.
+                */
+               if (DM_EVENT_ENABLED(ip, DM_EVENT_READ) &&
+                   !(iflags & BMV_IF_NO_DMAPI_READ)) {
+                       error = XFS_SEND_DATA(mp, DM_EVENT_READ, ip,
+                                             0, 0, 0, NULL);
+                       if (error)
+                               return XFS_ERROR(error);
+               }
+
+               if (ip->i_d.di_format != XFS_DINODE_FMT_EXTENTS &&
+                   ip->i_d.di_format != XFS_DINODE_FMT_BTREE &&
+                   ip->i_d.di_format != XFS_DINODE_FMT_LOCAL)
+                       return XFS_ERROR(EINVAL);
+
                if (xfs_get_extsz_hint(ip) ||
                    ip->i_d.di_flags & (XFS_DIFLAG_PREALLOC|XFS_DIFLAG_APPEND)){
                        prealloced = 1;
@@ -5926,42 +5930,34 @@ xfs_getbmap(
                        prealloced = 0;
                        fixlen = ip->i_size;
                }
-       } else {
-               prealloced = 0;
-               fixlen = 1LL << 32;
        }
 
        if (bmv->bmv_length == -1) {
                fixlen = XFS_FSB_TO_BB(mp, XFS_B_TO_FSB(mp, fixlen));
-               bmv->bmv_length = MAX( (__int64_t)(fixlen - bmv->bmv_offset),
-                                       (__int64_t)0);
-       } else if (bmv->bmv_length < 0)
-               return XFS_ERROR(EINVAL);
-       if (bmv->bmv_length == 0) {
+               bmv->bmv_length =
+                       max_t(__int64_t, fixlen - bmv->bmv_offset, 0);
+       } else if (bmv->bmv_length == 0) {
                bmv->bmv_entries = 0;
                return 0;
+       } else if (bmv->bmv_length < 0) {
+               return XFS_ERROR(EINVAL);
        }
+
        nex = bmv->bmv_count - 1;
        if (nex <= 0)
                return XFS_ERROR(EINVAL);
        bmvend = bmv->bmv_offset + bmv->bmv_length;
 
        xfs_ilock(ip, XFS_IOLOCK_SHARED);
-
-       if (((iflags & BMV_IF_DELALLOC) == 0) &&
-           (whichfork == XFS_DATA_FORK) &&
-           (ip->i_delayed_blks || ip->i_size > ip->i_d.di_size)) {
-               /* xfs_fsize_t last_byte = xfs_file_last_byte(ip); */
-               error = xfs_flush_pages(ip, (xfs_off_t)0,
-                                              -1, 0, FI_REMAPF);
-               if (error) {
-                       xfs_iunlock(ip, XFS_IOLOCK_SHARED);
-               return error;
+       if (whichfork == XFS_DATA_FORK && !(iflags & BMV_IF_DELALLOC)) {
+               if (ip->i_delayed_blks || ip->i_size > ip->i_d.di_size) {
+                       error = xfs_flush_pages(ip, 0, -1, 0, FI_REMAPF);
+                       if (error)
+                               goto out_unlock_iolock;
                }
-       }
 
-       ASSERT(whichfork == XFS_ATTR_FORK || (iflags & BMV_IF_DELALLOC) ||
-              ip->i_delayed_blks == 0);
+               ASSERT(ip->i_delayed_blks == 0);
+       }
 
        lock = xfs_ilock_map_shared(ip);
 
@@ -5972,23 +5968,24 @@ xfs_getbmap(
        if (nex > XFS_IFORK_NEXTENTS(ip, whichfork) * 2 + 1)
                nex = XFS_IFORK_NEXTENTS(ip, whichfork) * 2 + 1;
 
-       bmapi_flags = xfs_bmapi_aflag(whichfork) |
-                       ((iflags & BMV_IF_PREALLOC) ? 0 : XFS_BMAPI_IGSTATE);
+       bmapi_flags = xfs_bmapi_aflag(whichfork);
+       if (!(iflags & BMV_IF_PREALLOC))
+               bmapi_flags |= XFS_BMAPI_IGSTATE;
 
        /*
         * Allocate enough space to handle "subnex" maps at a time.
         */
        subnex = 16;
-       map = kmem_alloc(subnex * sizeof(*map), KM_SLEEP);
+       map = kmem_alloc(subnex * sizeof(*map), KM_MAYFAIL);
+       if (!map)
+               goto out_unlock_ilock;
 
        bmv->bmv_entries = 0;
 
-       if ((XFS_IFORK_NEXTENTS(ip, whichfork) == 0)) {
-               if (((iflags & BMV_IF_DELALLOC) == 0) ||
-                   whichfork == XFS_ATTR_FORK) {
-                       error = 0;
-                       goto unlock_and_return;
-               }
+       if (XFS_IFORK_NEXTENTS(ip, whichfork) == 0 &&
+           (whichfork == XFS_ATTR_FORK || !(iflags & BMV_IF_DELALLOC))) {
+               error = 0;
+               goto out_free_map;
        }
 
        nexleft = nex;
@@ -6000,10 +5997,12 @@ xfs_getbmap(
                                  bmapi_flags, NULL, 0, map, &nmap,
                                  NULL, NULL);
                if (error)
-                       goto unlock_and_return;
+                       goto out_free_map;
                ASSERT(nmap <= subnex);
 
                for (i = 0; i < nmap && nexleft && bmv->bmv_length; i++) {
+                       int full = 0;   /* user array is full */
+
                        out.bmv_oflags = 0;
                        if (map[i].br_state == XFS_EXT_UNWRITTEN)
                                out.bmv_oflags |= BMV_OF_PREALLOC;
@@ -6018,36 +6017,32 @@ xfs_getbmap(
                            whichfork == XFS_ATTR_FORK) {
                                /* came to the end of attribute fork */
                                out.bmv_oflags |= BMV_OF_LAST;
-                               goto unlock_and_return;
-                       } else {
-                               int full = 0;   /* user array is full */
-
-                               if (!xfs_getbmapx_fix_eof_hole(ip, &out,
-                                                       prealloced, bmvend,
-                                                       map[i].br_startblock)) {
-                                       goto unlock_and_return;
-                               }
-
-                               /* format results & advance arg */
-                               error = formatter(&arg, &out, &full);
-                               if (error || full)
-                                       goto unlock_and_return;
-                               nexleft--;
-                               bmv->bmv_offset =
-                                       out.bmv_offset + out.bmv_length;
-                               bmv->bmv_length = MAX((__int64_t)0,
-                                       (__int64_t)(bmvend - bmv->bmv_offset));
-                               bmv->bmv_entries++;
+                               goto out_free_map;
                        }
+
+                       if (!xfs_getbmapx_fix_eof_hole(ip, &out, prealloced,
+                                       bmvend, map[i].br_startblock))
+                               goto out_free_map;
+
+                       /* format results & advance arg */
+                       error = formatter(&arg, &out, &full);
+                       if (error || full)
+                               goto out_free_map;
+                       nexleft--;
+                       bmv->bmv_offset =
+                               out.bmv_offset + out.bmv_length;
+                       bmv->bmv_length =
+                               max_t(__int64_t, 0, bmvend - bmv->bmv_offset);
+                       bmv->bmv_entries++;
                }
        } while (nmap && nexleft && bmv->bmv_length);
 
-unlock_and_return:
+ out_free_map:
+       kmem_free(map);
+ out_unlock_ilock:
        xfs_iunlock_map_shared(ip, lock);
+ out_unlock_iolock:
        xfs_iunlock(ip, XFS_IOLOCK_SHARED);
-
-       kmem_free(map);
-
        return error;
 }
 

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