ファイルシステムの歴史: ジャーナリング編

Transcript

1. ϑΝΠϧγεςϜͷྺ࢙: δϟʔ
   φϦϯάฤ
   Naohiro Aota (@naota344)
   

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2. ࣗݾ঺հ
   ໊લ: ੨ా௚େ
   ͓͋ͨͳ͓ͻΖ
   @naota344
   ܚጯٛक़େֶͰϑΝΠϧγεςϜͷݚڀ
   Gentoo ίϛολ
   झຯ: FS Λյͨ͠ਓͷإ͕ݟ͍ͨ
   

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3. ࠷ۙͷ͜ͱ: btrfsck Λ͔͚ͯͨ
   

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4. ࡢ೔ btrfsck ͷதͷਓ͔
   Βϝʔϧ͕དྷͨ
   

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5. ࡢ೔ btrfsck ͷதͷਓ͔
   Βϝʔϧ͕དྷͨ
   ۙ೔ patch ͕౤ߘ༧ఆ!
   ͩͦ͏Ͱ͢
   

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6. ຊ೔ͷ͓୊
   δϟʔφϦϯάͷྺ࢙
   

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7. δϟʔφϦϯά
   ͖ͯͱʔʹ FS ʹॻ͘ͱ FS ͸յΕΔ
   Ұ؏ੑΛ࣋ͬͯॻ͘΂͖มߋ͕த్൒୺ʹͳͬ
   ͯյΕΔ
   δϟʔφϦϯά
   Ұ౓δϟʔφϧྖҬʹ͜Ε͔Βॻ͘಺༰Λࣄલ
   ʹॻ͘
   δϟʔφϧॻ͖ऴΘΔ -> ຊମʹॻ͖͜Έ
   ్தͰࢮΜͰ΋େৎ෉
   ͍ΘΏΔ write-ahead-logging
   

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8. δϟʔφϦϯάॳग़
   Reimplementing the Cedar file system using
   logging and group commit
   Robert Hagmann Xerox PARC
   1987 ೥
   Dorado, Dandelion ্Ͱಈ͍͍ͯͨ Cedar Λ
   Dragon ʹҠ২͢Δʹ͋ͨͬͯʮδϟʔφϦϯάʯ
   ͕௥Ճ͞Εͨ
   

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9. Cedar, Dorado, Dandelion, Dragon
   Cedar
   ϓϩάϥϛϯάݴޠͷ໊લ
   ͔ͭ, Cedar ͕ಈ࡞͢Δʮϓϩάϥϛϯά؀ڥʯ
   ͷ໊લ
   Dorado, Dandelion
   D-Machine, Lisp Ϛγϯ
   Dorado
   24bit ͱ͍͏ large virtual address space
   1024x808 ͷ large Ͱ high-resolution ͳനࠇσΟε
   ϓϨΠ
   ࠷େ 32MB ͷ෺ཧσΟεΫ
   

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10. લδϟʔφϦϯά࣌୅: TridentσΟε
    Ϋ
    Dorado, Dandelion ͸ Trident σΟεΫΛ࢖༻
    http://www.computerhistory.org/
    collections/catalog/102681543
    Image courtesy of Computer History Museum
    

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11. TridentσΟεΫ
    Trident disk for the Alto (1979)
    Trident σΟεΫͷඪ४తͳϑΥʔϚοτ͕ॻ͍
    ͍ͯΔ
    ֤τϥοΫ (10080 words) = 9 ηΫλ x 1120
    words
    ηΫλ͕ 3 ͭͷ෦෼ʹ෼͚ΒΕΔ
    ϔομ (2 words)
    ͦͷηΫλͷσΟεΫΞυϨε͕ॻ͍ͯ͋Δ
    ίϯτϩʔϥ͕ݕࠪ͢Δ
    ϥϕϧ (10 words)
    store file dependent information
    σʔλຊମ (1024 words)
    ֤ηΫλʹʮϥϕϧʯ͕෇͚ΒΕΔ
    

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12. δϟʔφϦϯάҎલͷCedar
    File Name Table ͸ B-tree
    FS ্ͷશͯͷ file ͷ໊લͱ header ৘ใΛอ࣋
    ϥϕϧΛ༻͍ͨҰ؏ੑอূ
    uid, page number
    page type (header, free, data) ͕ه࿥͞ΕΔ
    

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13. FSD (File System for Dragon)
    

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14. ͦͷଞ
    ࠓ೔͸ FS յΕͯͳ͍͚Ͳɺ εϥΠυॻ
    ͨ͘Ίͷ Emacs ͕ SEGV Ͱىಈ͠ͳ
    ͔ͬͨΓɺԿ౓΋࿈ଧͯͨ͠Βٸʹىಈ
    ͯ͠Έ͍ͨͳײ͡ʹͳΓ·ͨ͠
    

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15. ͳΜͰ?
    emacs/src/xfns.c
    XGetICValues
    X ͷ input context ͷ৘ใͱͬͯ͘Δ
    Τϥʔͩͱ࠷ॳͷͱΕͳ͔ͬͨଐੑ໊͕ฦΔ
    attr = XVaCreateNestedList (0, XNAreaNeeded, &needed, NULL);
    XGetICValues (xic, XNStatusAttributes, attr, NULL);
    XFree (attr);
    if (needed->width == 0)
    {
    attr = XVaCreateNestedList (0, XNArea, &needed, NULL);
    XGetICValues (xic, XNStatusAttributes, attr, NULL);
    XFree (attr);
    }
    ʜ
    XFree (needed); <- ͜͜ͰࢮΜͰΔ
    

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16. ͦΓΎʔ͠ΐΜ
    ͳΜͰଐੑऔಘΤϥʔʹͳͬͯͨ?
    imsettings ͷ͍ͤͬΆ͍: imsettings = ͍ΖΜͳ
    IM ͷڞ௨ϨΠϠʹ͓Ε͕ͳΔ! uim ͱ͔ fcitx
    Λಈతʹม͑ΒΕΔͥ!
    ͦΓΎʔ͠ΐΜ
    XMODIFIERS=@im=fcitx emacs
    XMODIFIERS= emacs
    

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17. ·ͱΊ
    δϟʔφϦϯάͷ࿩Λੲ͔Βࠓ·Ͱͬ͘͞ͱ
    ͨ͠
    imsettings ͸ͩΊͩ
    

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