[qemu-xen staging-4.13] block/file-posix: Reduce xfsctl() use

[patchbot@xxxxxxx]

commit 6f1a94035b02d3676a897ea5fa4cda4c62128228
Author:     Max Reitz <mreitz@xxxxxxxxxx>
AuthorDate: Fri Aug 23 15:03:40 2019 +0200
Commit:     Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
CommitDate: Sun Oct 27 23:45:18 2019 -0500

    block/file-posix: Reduce xfsctl() use
    
    This patch removes xfs_write_zeroes() and xfs_discard().  Both functions
    have been added just before the same feature was present through
    fallocate():
    
    - fallocate() has supported PUNCH_HOLE for XFS since Linux 2.6.38 (March
      2011); xfs_discard() was added in December 2010.
    
    - fallocate() has supported ZERO_RANGE for XFS since Linux 3.15 (June
      2014); xfs_write_zeroes() was added in November 2013.
    
    Nowadays, all systems that qemu runs on should support both fallocate()
    features (RHEL 7's kernel does).
    
    xfsctl() is still useful for getting the request alignment for O_DIRECT,
    so this patch does not remove our dependency on it completely.
    
    Note that xfs_write_zeroes() had a bug: It calls ftruncate() when the
    file is shorter than the specified range (because ZERO_RANGE does not
    increase the file length).  ftruncate() may yield and then discard data
    that parallel write requests have written past the EOF in the meantime.
    Dropping the function altogether fixes the bug.
    
    Suggested-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
    Fixes: 50ba5b2d994853b38fed10e0841b119da0f8b8e5
    Reported-by: Lukáš Doktor <ldoktor@xxxxxxxxxx>
    Cc: qemu-stable@xxxxxxxxxx
    Signed-off-by: Max Reitz <mreitz@xxxxxxxxxx>
    Reviewed-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
    Reviewed-by: John Snow <jsnow@xxxxxxxxxx>
    Tested-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
    Tested-by: John Snow <jsnow@xxxxxxxxxx>
    Signed-off-by: Kevin Wolf <kwolf@xxxxxxxxxx>
    (cherry picked from commit b2c6f23f4a9f6d8f1b648705cd46d3713b78d6a2)
    Signed-off-by: Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
---
 block/file-posix.c | 77 +-----------------------------------------------------
 1 file changed, 1 insertion(+), 76 deletions(-)

diff --git a/block/file-posix.c b/block/file-posix.c
index 4479cc7ab4..992eb4a798 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -1445,59 +1445,6 @@ out:
     }
 }
 
-#ifdef CONFIG_XFS
-static int xfs_write_zeroes(BDRVRawState *s, int64_t offset, uint64_t bytes)
-{
-    int64_t len;
-    struct xfs_flock64 fl;
-    int err;
-
-    len = lseek(s->fd, 0, SEEK_END);
-    if (len < 0) {
-        return -errno;
-    }
-
-    if (offset + bytes > len) {
-        /* XFS_IOC_ZERO_RANGE does not increase the file length */
-        if (ftruncate(s->fd, offset + bytes) < 0) {
-            return -errno;
-        }
-    }
-
-    memset(&fl, 0, sizeof(fl));
-    fl.l_whence = SEEK_SET;
-    fl.l_start = offset;
-    fl.l_len = bytes;
-
-    if (xfsctl(NULL, s->fd, XFS_IOC_ZERO_RANGE, &fl) < 0) {
-        err = errno;
-        trace_file_xfs_write_zeroes(strerror(errno));
-        return -err;
-    }
-
-    return 0;
-}
-
-static int xfs_discard(BDRVRawState *s, int64_t offset, uint64_t bytes)
-{
-    struct xfs_flock64 fl;
-    int err;
-
-    memset(&fl, 0, sizeof(fl));
-    fl.l_whence = SEEK_SET;
-    fl.l_start = offset;
-    fl.l_len = bytes;
-
-    if (xfsctl(NULL, s->fd, XFS_IOC_UNRESVSP64, &fl) < 0) {
-        err = errno;
-        trace_file_xfs_discard(strerror(errno));
-        return -err;
-    }
-
-    return 0;
-}
-#endif
-
 static int translate_err(int err)
 {
     if (err == -ENODEV || err == -ENOSYS || err == -EOPNOTSUPP ||
@@ -1553,10 +1500,8 @@ static ssize_t 
handle_aiocb_write_zeroes_block(RawPosixAIOData *aiocb)
 static int handle_aiocb_write_zeroes(void *opaque)
 {
     RawPosixAIOData *aiocb = opaque;
-#if defined(CONFIG_FALLOCATE) || defined(CONFIG_XFS)
-    BDRVRawState *s = aiocb->bs->opaque;
-#endif
 #ifdef CONFIG_FALLOCATE
+    BDRVRawState *s = aiocb->bs->opaque;
     int64_t len;
 #endif
 
@@ -1564,12 +1509,6 @@ static int handle_aiocb_write_zeroes(void *opaque)
         return handle_aiocb_write_zeroes_block(aiocb);
     }
 
-#ifdef CONFIG_XFS
-    if (s->is_xfs) {
-        return xfs_write_zeroes(s, aiocb->aio_offset, aiocb->aio_nbytes);
-    }
-#endif
-
 #ifdef CONFIG_FALLOCATE_ZERO_RANGE
     if (s->has_write_zeroes) {
         int ret = do_fallocate(s->fd, FALLOC_FL_ZERO_RANGE,
@@ -1632,14 +1571,6 @@ static int handle_aiocb_write_zeroes_unmap(void *opaque)
     }
 #endif
 
-#ifdef CONFIG_XFS
-    if (s->is_xfs) {
-        /* xfs_discard() guarantees that the discarded area reads as all-zero
-         * afterwards, so we can use it here. */
-        return xfs_discard(s, aiocb->aio_offset, aiocb->aio_nbytes);
-    }
-#endif
-
     /* If we couldn't manage to unmap while guaranteed that the area reads as
      * all-zero afterwards, just write zeroes without unmapping */
     ret = handle_aiocb_write_zeroes(aiocb);
@@ -1716,12 +1647,6 @@ static int handle_aiocb_discard(void *opaque)
         ret = -errno;
 #endif
     } else {
-#ifdef CONFIG_XFS
-        if (s->is_xfs) {
-            return xfs_discard(s, aiocb->aio_offset, aiocb->aio_nbytes);
-        }
-#endif
-
 #ifdef CONFIG_FALLOCATE_PUNCH_HOLE
         ret = do_fallocate(s->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
                            aiocb->aio_offset, aiocb->aio_nbytes);
--
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