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Rewrite the comments that explain swapon_trim() to make them more
comprehensible. Suggested by: rpokala Approved by: markj (mentor) Differential Revision: https://reviews.freebsd.org/D21034
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=350359
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@ -746,9 +746,11 @@ swapon_trim(const char *name)
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off_t ioarg[2], sz;
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off_t ioarg[2], sz;
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int error, fd;
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int error, fd;
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/* Open a descriptor to create a consumer of the device. */
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fd = open(name, O_WRONLY);
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fd = open(name, O_WRONLY);
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if (fd < 0)
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if (fd < 0)
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errx(1, "Cannot open %s", name);
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errx(1, "Cannot open %s", name);
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/* Find the device size. */
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if (fstat(fd, &sb) < 0)
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if (fstat(fd, &sb) < 0)
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errx(1, "Cannot stat %s", name);
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errx(1, "Cannot stat %s", name);
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if (S_ISREG(sb.st_mode))
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if (S_ISREG(sb.st_mode))
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@ -758,18 +760,22 @@ swapon_trim(const char *name)
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err(1, "ioctl(DIOCGMEDIASIZE)");
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err(1, "ioctl(DIOCGMEDIASIZE)");
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} else
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} else
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errx(1, "%s has an invalid file type", name);
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errx(1, "%s has an invalid file type", name);
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/* Trim the device. */
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ioarg[0] = 0;
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ioarg[0] = 0;
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ioarg[1] = sz;
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ioarg[1] = sz;
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if (ioctl(fd, DIOCGDELETE, ioarg) != 0)
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if (ioctl(fd, DIOCGDELETE, ioarg) != 0)
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warn("ioctl(DIOCGDELETE)");
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warn("ioctl(DIOCGDELETE)");
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/*
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/* Start using the device for swapping, creating a second consumer. */
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* swapon is invoked after trimming, so that the trimming doesn't happen
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* after the device is in use for swapping, but before the fd is closed,
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* for the benefit of geli, which could otherwise detach the device,
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* before swapon, on close.
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*/
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error = swapon(name);
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error = swapon(name);
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/*
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* Do not close the device until the swap pager has attempted to create
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* another consumer. For GELI devices created with the 'detach -l'
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* option, removing the last consumer causes the device to be detached
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* - that is, to disappear. This ordering ensures that the device will
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* not be detached until swapoff is called.
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*/
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close(fd);
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close(fd);
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return (error);
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return (error);
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}
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}
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